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1
Park, R. "Evaluation of ductility of structures and structural assemblages from laboratory testing." Bulletin of the New Zealand Society for Earthquake Engineering 22, no. 3 (September 30, 1989): 155–66. http://dx.doi.org/10.5459/bnzsee.22.3.155-166.
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Definitions for the required and available ductility used in seismic design are discussed. Methods for estimating the yield deformation and the maximum available deformation are described and suggestions are made for appropriate definitions. Examples are given of different imposed histories of inelastic displacement which have been used in the experimental testing of structures and structural assemblages in which cycles of quasi-static loading are applied. A quasi-static procedure for establishing the available ductility factor of a subassemblage by laboratory testing is recommended.
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Zhou, Yingwu, Li Zhuang, Zhiheng Hu, Biao Hu, Xiaoxu Huang, and Zhongfeng Zhu. "Perforated steel for realizing extraordinary ductility under compression: Testing and finite element modeling." REVIEWS ON ADVANCED MATERIALS SCIENCE 61, no. 1 (January 1, 2022): 195–207. http://dx.doi.org/10.1515/rams-2022-0021.
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Abstract One key obstacle restricting the application of fiber-reinforced polymer (FRP) bars from being used as reinforcement in structural concrete is the significantly reduced ductility because FRP under tension is linear elastic up to brittle rupture at small strain. Recently, a new structural concept, compression yielding (CY), has been proposed as a way to overcome the insufficient ductility of concrete structures reinforced with FRP bars or other non-ductile materials. In the CY structural system, the compression-zone of normal concrete is replaced by a ductile material within the plastic hinge. This enables the flexural deformation to be achieved by the compressive deformation of CY material rather than a tensile deformation of longitudinal reinforcing bars. To this end, an ideal CY material requires strength to be maintained during the extraordinarily large deformation process. This study tries to identify methods for developing this kind of CY material by designing and optimizing perforations inside a mild steel block. The effects of key parameters, including ratio, diameter, and arrangement of perforations on the stiffness, strength, and ductility of CY materials were experimentally investigated. In addition, a finite element (FE) model was developed to predict the behavior of the proposed CY material.
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Park, R. "A static force-based procedure for the seismic assessment of existing reinforced concrete moment resisting frames." Bulletin of the New Zealand Society for Earthquake Engineering 30, no. 3 (September 30, 1997): 213–26. http://dx.doi.org/10.5459/bnzsee.30.3.213-226.
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A force-based seismic assessment procedure for existing reinforced concrete moment resisting frames is discussed. The assessment procedure is based on determining the probable strength and ductility of the critical mechanism of post-elastic deformation of the frame. Account is taken of the likely seismic behaviour of reinforced concrete beams, columns and beam-column joints with substandard reinforcement details typical of structures designed before the 1970s, as determined by the results of experimental testing and analytical studies. The assessment aims at determining the available lateral load strength and structural (displacement) ductility factor of the frames so that the designer can determine the likely seismic performance of the structure by referring to acceleration response spectra for design earthquake forces for various levels of structural ductility factor.
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Hou, Hetao, Weiqi Fu, Canxing Qiu, Jirun Cheng, Zhe Qu, Wencan Zhu, and Tianxiang Ma. "Effect of axial compression ratio on concrete-filled steel tube composite shear wall." Advances in Structural Engineering 22, no. 3 (August 28, 2018): 656–69. http://dx.doi.org/10.1177/1369433218796407.
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This study proposes a new type of shear wall, namely, the concrete-filled steel tube composite shear wall, for high performance seismic force resisting structures. In order to study the seismic behavior of concrete-filled steel tube composite shear wall, cyclic loading tests were conducted on three full-scale specimens. One conventional reinforced concrete shear wall was included in the testing program for comparison purpose. Regarding the seismic performance of the shear walls, the failure mode, deformation capacity, bearing capacity, ductility, hysteretic characteristics, and energy dissipation are key parameters in the analysis procedure. The testing results indicated that the bearing capacity, the ductility, and the energy dissipation of the concrete-filled steel tube composite shear walls are greater than that of conventional reinforced concrete shear walls. In addition, the influence of axial compression ratio on the seismic behavior of concrete-filled steel tube composite shear wall is also investigated. It was found that higher axial compression ratio leads to an increase in the bearing capacity of concrete-filled steel tube composite shear walls while a reduction in the ductility capacity.
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Lee, Hee Keun, Jin Yong Kim, and In Hwan Hwang. "Analysis of Weld Defects in Offshore Structural H Beams." Materials Science Forum 580-582 (June 2008): 37–40. http://dx.doi.org/10.4028/www.scientific.net/msf.580-582.37.
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H beam welds along rolling and transverse direction were investigated with nondestructive testing, mechanical testing and microstructural analysis. Crack and fracture occurred, during guided bend testing, in the specimens welded along rolling direction between flanges of the H beams with higher S content although no defect was detected prior to the bend test. The fracture seemed to be lamellar tearing because of step-like fracture propagation and terrace and wall fracture appearance of the ruptured bend test specimen. On top of this, lamellar tear was already created in the base metal area near the HAZ before the bend test in microstructural analysis on the welds. It seems that lamellar tearing occurred in the specimens welded along rolling direction between flanges of the H beams with higher S content as cracks were formed and propagated into a ferrite phase region in α-γ band structure in combination with low ductility in transverse direction due to MnS inclusions elongated along rolling direction.
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Bradley, Cameron R., Larry A. Fahnestock, Eric M. Hines, and Joshua G. Sizemore. "Full-Scale Cyclic Testing of Low-Ductility Concentrically Braced Frames." Journal of Structural Engineering 143, no. 6 (June 2017): 04017029. http://dx.doi.org/10.1061/(asce)st.1943-541x.0001760.
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Hajj, Ramez, Rachel Hure, and Amit Bhasin. "Evaluation of Stiffness, Strength, and Ductility of Asphalt Binders at an Intermediate Temperature." Transportation Research Record: Journal of the Transportation Research Board 2632, no. 1 (January 2017): 44–51. http://dx.doi.org/10.3141/2632-05.
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The search for a test and parameter that can effectively describe the fatigue cracking resistance of an asphalt binder has led to many approaches. Of these, researchers have used stiffness, strength, and ductility-based criteria to screen binders on the basis of inherent resistance to cracking. In this study, poker chip testing on thin films of asphalt binder was used at intermediate temperatures to obtain both stress and ductility-based properties of eight binders. In addition, a dynamic shear rheometer frequency sweep at an intermediate temperature was conducted to obtain stiffnesses of the binders and a surrogate parameter for ductility. The results showed no relationship between strength and stiffness. In most cases, binders that were rated to have high ductility on the basis of the dynamic shear rheometer parameter also had high toughness on the basis of the poker chip test. However, some binders clearly departed from this trend, with at least one binder exhibiting both ideally desired high stiffness and toughness. Examination of failure surfaces from the poker chip test provided additional information about the mechanisms that drove failure.
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Fukumoto, Y., T. Takaku, T. Aoki, and K. A. S. Susantha. "Innovative Use of Profiled Steel Plates for Seismic Structural Performance." Advances in Structural Engineering 8, no. 3 (July 2005): 247–57. http://dx.doi.org/10.1260/1369433054349051.
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This paper presents the innovative use of hot-rolled thickness-tapered mill products, longitudinally profiled (LP) plates, for the seismic performance of bridge bents of single and portal framed piers. The study involves the inelastic cyclic testing and numerical analysis of tested beam-columns and portal frames in order to evaluate the effects of tapering ratios of LP plates, penetration of yielding, and number of locally buckled panels on their structural ductility. A structural design method is proposed for the portal frames having LP panels under cyclic loadings.
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Radnic, Jure, Radoslav Markic, Alen Harapin, Domagoj Matesan, and Goran Baloevic. "Stirrup effects on compressive strength and ductility of confined concrete columns." World Journal of Engineering 10, no. 6 (December 1, 2013): 497–506. http://dx.doi.org/10.1260/1708-5284.10.6.497.
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The results of experimental testing of stirrup effects on compressive strength and ductility of axially loaded confined reinforced concrete columns of rectangular cross-section are presented. Effects of different concrete strengths, different stirrup bar diameters and different stirrup spacing on column's bearing capacity and ductility have been researched.
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Bu, Yonghong, Qi Yang, Yihong Wang, and Dongfang Zhang. "Cyclic Testing of Bolt-Weld Joints Reinforced by Sleeves Connecting Circular CFST Columns to Steel Beams." Advances in Civil Engineering 2020 (January 28, 2020): 1–12. http://dx.doi.org/10.1155/2020/9674128.
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This study examined the design of joints reinforced by sleeves for connecting circular concrete-filled steel tube columns to steel beams. Six half-scale specimens, including four bolt-weld joints reinforced by sleeves and two bolt and stiffened end-plate joints, were designed and tested under cyclic loading to evaluate the seismic behavior of these joints. The joint construction and beam-column stiffness ratio were taken as the main parameters in the tests. The seismic behaviors, including the failure modes, hysteretic curves, ductility, strength and stiffness degradation, and energy dissipation, were investigated. The experimental results showed that no obvious bolt loosening, fracture, or widespread weld cracking appeared in the joints reinforced by sleeves. Furthermore, the joint strength and stiffness were markedly increased by the sleeves in the joint core area. Overall, most specimens exhibited full hysteresis loops and excellent ductilities, the equivalent viscous damping coefficients were 0.263∼0.532, and the ductility coefficients were 1.77∼3.42. The interstory drift ratios satisfied the requirements specified by technical regulations. The connections of these types exhibit favorable energy dissipations and can be effectively utilized for building construction in earthquake-prone areas. This research should contribute to the future engineering applications of concrete-filled steel tube to composite structure.
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Longauerová, Margita, Mirko Hodur, Marek Vojtko, Pavol Zubko, Miroslav Glogovský, Mária Demčáková, Miloš Matvija, and Tibor Kvačkaj. "Structural Nature of ZnAl4Cu1 Alloy Plasticity Affected by Various Technological Treatments." Defect and Diffusion Forum 405 (November 2020): 92–99. http://dx.doi.org/10.4028/www.scientific.net/ddf.405.92.
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The aim of this work was to analyse the microstructural nature of plasticity in ZnAl4Cu1 alloy and its dependence on the processing technology. The alloy condition was analysed after gravity casting, after forging and after ECAP processing. Two alloys with slightly different compositions were studied. For alloy A, the returnable material from a prominent Zn alloy producer was used. For B alloy input raw materials of relatively high purity were used. Tensile testing showed that in the as-cast alloy tensile strength had relatively low levels up to 211 MPa, and particularly low values of ductility only up to 2.5 % were found in B alloy, which was more polluted. By means of ECAP processing of the as-cast alloy, the tensile strength was improved by 50 % (Rm = 312 MPa). In the case of the purer A alloy the majority of samples improved to level A = 27.9 %. Forging of the as-cast alloy preserved strength on a level similar to the ECAP result, but ductility was improved to the level of 34.4 %, although alloy B had lower purity. Further significant ductility improvement was obtained through ECAP processing to A = 147 % of the as-forged alloy. The microstructure of ZnAl4Cu1 consists primarily of segregated η phase (rich in Zn) and fine eutectoid composed of η and alpha phases segregated mostly in dispersive state, but in places also in lamellar form. Close correlation between microstructure and processing method resulted from our fractographic study. In the case of ECAP processing of the forged state the finest microstructure was achieved, which was accompanied by higher plasticity and also by fine dimples of transcrystalline ductile fracture (DTDF).
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Mousseau, Sébastien, and Patrick Paultre. "Seismic performance of a full-scale, reinforced high-performance concrete building. Part I: Experimental study." Canadian Journal of Civil Engineering 35, no. 8 (August 2008): 832–48. http://dx.doi.org/10.1139/l08-017.
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Full-scale tests provide valuable information on the characteristics of building structures that can be used to evaluate design methods, to calibrate modelling techniques, and to determine damage corresponding to loading levels. These tests are scarce due to the enormous requirements in testing space and specialized testing equipment. The seismic behaviour of a full-scale, two-storey, reinforced high-performance concrete building designed with moderate ductility detailing is evaluated by pseudo-dynamic testing, during which increasing seismic loads are applied, resulting in increasing levels of permanent damage to the structure. To monitor the level of damage, a series of successive forced-vibration tests are also carried out at each step of the process and are used to track changes in the key dynamic properties of the building. The paper presents the design of the test structure according to the new edition of the CSA A23.3-04 Design of concrete structures standard, the series of pseudo-dynamic tests simulating different levels of earthquake excitation consistent with the 2005 edition of the National building code of Canada, and the evaluation of the performance of the building. It is shown that the detailing requirements of CSA A23.3-04 are more than adequate to provide the ductility and overstrength expected.
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Zhang, Dongfang, Junhai Zhao, and Shuanhai He. "Cyclic Testing of Concrete-Filled Double-Skin Steel Tubular Column to Steel Beam Joint with RC Slab." Advances in Civil Engineering 2018 (July 26, 2018): 1–15. http://dx.doi.org/10.1155/2018/7126393.
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The design of composite joints for connecting concrete-filled double-skin tubular (CFDST) columns to steel beams supporting reinforced concrete (RC) slabs is presented in this paper. Five half-scale specimens were designed, including four composite joints with RC slab and one bare steel beam joint, and were tested under a constant axially compressive force and lateral cyclic loading at the top end of the column to evaluate their seismic behavior. The main experimental parameters were the construction of the joint and the type of the column. The seismic behaviors, including the failure modes, hysteresis curves, ductility, strength and stiffness degradation, and energy dissipation, were investigated. The failure modes of the composite joints depended on the joint construction and on the stiffness ratio of beams to columns. Joints of stiffening type had significantly higher load-bearing and deformation capacities than joints of nonstiffening type. Compared with the bare steel beam joint, the bearing capacities of the composite joints with RC slabs were markedly increased. The composite action was remarkable under sagging moments, resulting in larger deformation on the bottom flanges of the beams. Overall, most specimens exhibited full hysteresis loops, and the equivalent viscous damping coefficients were 0.282∼0.311. The interstory drift ratios satisfied the requirements specified by technical regulations. Composite connections of this type exhibit excellent ductility and favorable energy dissipation and can be effectively utilized in superhigh-rise buildings erected in earthquake zones.
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Guravich, Susan J., and John L. Dawe. "Simple beam connections in combined shear and tension." Canadian Journal of Civil Engineering 33, no. 4 (April 1, 2006): 357–72. http://dx.doi.org/10.1139/l05-057.
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An investigation into the behaviour of simple beam-to-column connections subjected to combined shear and tension was carried out by testing 108 full-scale specimens, including header angle, knife angle, single angle, and shear tab configurations. Specimens were rotated 0.03 rad, and a prescribed shear between zero and the design shear resistance was held constant while the specimens were loaded in tension to failure. Results showed significant differences in serviceability, ductility, interactions, and ultimate tension strength. Ductility was provided through yielding in bearing at bolt holes, bending of angle legs, and shear yielding of the gross section of connection elements. Tension and shear load versus displacement plots were acquired for all tests because of ductility and serviceability considerations in design. Existing methods of determining connection resistance, including bolt shear, net section shear, and bearing resistance, were used to compare predicted capacity with test results. The findings of the test program indicate that most simple connections can sustain significant amounts of tension in combination with design shear capacity.Key words: beam, connections, shear, tension, experimental, design, steel.
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Ferreira-Palma, Carlos, Héctor J. Dorantes-Rosales, Víctor M. López-Hirata, and Alberto A. Torres-Castillo. "Effect of Ag additions on the microstructure and phase transformations of Zn-22Al-2Cu (wt.%) alloy." International Journal of Materials Research 112, no. 2 (February 1, 2021): 108–17. http://dx.doi.org/10.1515/ijmr-2020-8009.
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Abstract The relationship between microstructure and mechanical properties is studied for eutectoid Zn-22Al (wt.%) alloys modified with Cu and Ag. Three alloys with a Cu content of 2 wt.% and varying amounts of Ag were cast and hot-extruded. Different microstructural characteristics were induced by heat treatments: natural aging, artificial aging and furnace cooling. Structural and microstructural characterizations were carried out with X-ray diffraction and scanning electron microscopy. Mechanical properties were determined by tensile testing. Dilatometry was used for determining the effects of composition on the transformation points. The addition of Ag increased the ε phase fraction and provided solid solution strengthening, improving the mechanical strength and reducing ductility. Ag additions also displaced the eutectoid reaction to higher temperatures. The microstructure of the matrix has proven to have a strong impact on mechanical properties. The naturally aged specimens presented the highest ductility and tensile strength; however, these properties are severely affected by aging. Lamellar microstructures present the lowest ductility and values of tensile strength between those of the natural and artificially-aged specimens.
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Duda, Szymon, Grzegorz Lesiuk, Paweł Zielonka, Paweł Stabla, Marek Lubecki, and Grzegorz Ziółkowski. "Flexural Pseudo-Ductility Effect in Hybrid GFRP/CFRP Bars under Static Loading Conditions." Materials 14, no. 19 (September 27, 2021): 5608. http://dx.doi.org/10.3390/ma14195608.
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The problem with composite rebars in the civil engineering industry is often described as the material’s brittleness while overloaded. To overcome this drawback, researchers pay attention to the pseudo-ductility effect. The paper presents four-point bending tests of pure unidirectional (UD) rods with additional composite layers obtained by filament winding and hand braiding techniques. Two types of core materials, glass FRP (fibre reinforced polymer) and carbon FRP, were used. Regarding the overwrapping material, the filament winding technique utilized carbon and glass roving reinforcement in the epoxy matrix, while in the case of hand braiding, the carbon fibre sleeve was applied with the epoxy matrix. Microstructural analysis using scanning electron microscopy (SEM) and computed tomography (CT) was performed to reveal the structural differences between the two proposed methods. Mechanical test results showed good material behaviour exhibiting the pseudo-ductility effect after the point of maximum force. The two applied overwrapping techniques had different influences on the pseudo-ductility effect. Microstructural investigation revealed differences between the groups of specimens that partially explain their different characters during mechanical testing.
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Chen, Wen Feng, Xiao Hui Yuan, and Bin Li. "Experimental Study on Seismic Performance of AAS-CFST Column." Applied Mechanics and Materials 670-671 (October 2014): 344–48. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.344.
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Three model specimens of alkali-activated slag concrete filled steel tube (AAS-CFST) with different axial compression ratio and steel ratio were designed and tested in the present study. The seismic performance of the structures were evaluated by testing them with combined lateral constant compression and vertical cyclic loads. The structural performance, such as the testing observations, hysteretic behavior, skeleton curve, stiffness degradation, energy dissipation capacity and ductility performance was discussed in detailed. The results show that all the specimens’ damage were bending deformation mode, and the hysteretic curves are relatively smooth. Test data indicated that increased the axial compression ratio improved the load bearing capacity, initial stiffness.
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Tamil Selvi, M., and T. S. Thandavamoorthy. "Load-Deflection Characteristics Of Steel, Polypropylene And Hybrid Fiber Reinforced Concrete Beams." Archives of Civil Engineering 61, no. 1 (March 1, 2015): 59–72. http://dx.doi.org/10.1515/ace-2015-0004.
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AbstractConcrete is the most widely used construction material because of its specialty of being cast into any desired shape. The main requirements of earthquake resistant structures are good ductility and energy absorption capacity. Fiber reinforced concrete possesses high flexural and tensile strength, improved ductility, and high energy absorption over the conventional concrete in sustaining dynamic loads. The aim of this paper is to compare the properties of concrete beams in which three types of fibers are added individually. Steel fibers, polypropylene fibers and hybrid fibers were added to concrete in the weight ratio of four percentages in the preparation of four beam specimens. The fourth specimen did not contain fibers and acted as a control specimen. The dimensions of the beam specimens were 150 mm × 150 mm × 700 mm. The reinforced concrete beams of M30 grade concrete were prepared for casting and testing. Various parameters such as load carrying capacity, stiffness degradation, ductility characteristics and energy absorption capacity of FRC beams were compared with that of RC beams. The companion specimens were cast and tested to study strength properties and then the results were compared. All the beams were tested under three point bending under Universal Testing Machine (UTM). The results were evaluated with respect to modulus of elasticity, first crack load, ultimate load, and ultimate deflection. The test result shows that use of hybrid fiber improves the flexural performance of the reinforced concrete beams. The flexural behavior and stiffness of the tested beams were calculated, and compared with respect to their load carrying capacities. Comparison was also made with theoretical calculations in order to determine the load-deflection curves of the tested beams. Results of the experimental programme were compared with theoretical predictions. Based on the results of the experimental programme, it can be concluded that the addition of steel, polypropylene and hybrid fibers by 4% by weight of cement (but 2.14 % by volume of cement) had the best effect on the stiffness and energy absorption capacity of the beams.
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Mena, Álvaro, Jorge Franco, Daniel Miguel, Jesús Mínguez, Ana Carla Jiménez, Dorys Carmen González, and Miguel Ángel Vicente. "Experimental Campaign of a Low-Cost and Replaceable System for Passive Energy Dissipation in Precast Concrete Structures." Applied Sciences 10, no. 4 (February 11, 2020): 1213. http://dx.doi.org/10.3390/app10041213.
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This research develops a new low-cost energy dissipation system, capable of being implemented in residential structures in developing countries with high seismic activity, in which the current solutions are not economically viable. These residential structures are entirely made of precast concrete elements (foundations, walls, and slabs). A solution is developed that consists of a new connection between a precast foundation and a structural wall, which is capable of dissipating almost all the seismic energy, and therfore protecting the rest of the building from structural damage. To validate the solution, a testing campaign is carried out, including a first set of “pushover” tests on isolated structural walls, a second set of “pushover” tests on structural frames, and a final set of seismic tests on a real-scale three-storey building. For the first and second set of tests, ductility is analyzed in accordance with ACI 374.2R-13, while for the third one, the dynamic response to a reference earthquake is evaluated. The results reveal that the solution developed shows great ductility and no relevant damage is observed in the rest of the building, except in the low-cost energy dissipation system. Once an earthquake has finished, a precast building implemented with this low-cost energy dissipation system is capable of showing a structural performance level of “immediate occupancy” according to ACI 374.2R-13.
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Hemamathi, L., and K. P. Jaya. "Behaviour of Precast Column Foundation Connection under Reverse Cyclic Loading." Advances in Civil Engineering 2021 (April 7, 2021): 1–17. http://dx.doi.org/10.1155/2021/6677007.
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Precast column foundation connection is one of the critical connections under reverse cyclic loading, and the present study focuses on this connection. Three types of connections were considered, such as (i) base plate connection, (ii) pocket connection, and (iii) grouted sleeve connection. All the above connections were designed, and experimental investigation was carried out on 1 : 2 scaled models by subjecting the column to lateral reverse cyclic loading. Displacement-controlled loading pattern has been adopted for the testing of the specimens. The structural response of the connection was studied for their (i) load-displacement hysteresis behaviour, (ii) stiffness degradation, (iii) energy dissipation, and (iv) ductility. The results were then compared with that of the monolithic connection. The precast connection was more ductile, and the energy dissipated by the pocket connection was high compared to the base plate and grouted sleeve connection. The ductility and the load-carrying of grouted sleeve connection were small compared to other connections. The results of the study showed the precast column foundation can be used in seismic prone areas.
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Xiao, Congzhen, Baojuan Qiao, Jianhui Li, Zhiyong Yang, and Jiannan Ding. "Prediction of Transverse Reinforcement of RC Columns Using Machine Learning Techniques." Advances in Civil Engineering 2022 (November 22, 2022): 1–15. http://dx.doi.org/10.1155/2022/2923069.
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Transverse reinforcement of reinforced concrete (RC) columns contributes greatly to the ductility deformation capacity of RC structures. The existing models to predict the amount of transverse reinforcement required are all empirical models with low accuracy and large dispersion and have not considered the real ductility demand of individual components. This paper proposes a ductility design method of RC structure based on component drift ratio demand obtained from nonlinear structural dynamic analysis. To establish the best transverse reinforcement ratio prediction model for RC columns, based on an experimental database consisting of 498 columns, 12 machine learning (ML) models are trained. To solve the over-fitting problem caused by the current situation of “few samples and big errors” of the experimental database, feature engineering aiming at dimension reduction is systematically carried out through an iterative process. Through comprehensive performance evaluation on the testing set, an XGBoost model is selected. To interpret the “black box” ML model, the SHAP method and partial dependence plots are used to analyse the correlation between the input parameters and the transverse reinforcement ratio. The interpretation results are consistent with mechanical laws and engineering experience, which prove the reliability of the selected ML model. Compared with two existing empirical models, the proposed XGBoost model shows higher accuracy and smaller deviation. After safety probability analysis, the trained XGBoost model is transformed into C code and integrated into seismic design software for productive practice. An open-source data-driven model to predict the transverse reinforcement ratio required for RC columns is provided worldwide, with the flexibility to account for additional experimental results.
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Al Rikabi, Fouad T., Shad M. Sargand, Issam Khoury, and John Kurdziel. "A new test method for evaluating the long-term performance of fiber-reinforced concrete pipes." Advances in Structural Engineering 23, no. 7 (December 19, 2019): 1336–49. http://dx.doi.org/10.1177/1369433219894243.
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Synthetic fibers have been used recently to minimize the need for steel reinforcement in the concrete pipe to enhance their ductility. However, synthetic fiber has properties that may change over time due to its viscoelastic behavior. The objective of this study is to investigate the long-term performance of fiber-reinforced concrete pipes using a new test frame. A three-dimensional finite element model was created for the long-term testing frame to ensure its compliance with the American Society for Testing and Materials requirement. The finite element results showed that the testing frame successfully transferred the load to the concrete as the pipe cracked at the location where high flexural stresses are expected. Concrete pipe reinforced with synthetic fiber dosage of 9 kg/m3 along the steel reinforcement area of 5.7 cm2/m was tested to evaluate the concrete pipe system performance. The pipe was tested under two load stages for 120 days each. Load stages 1 and 2 included applying 40% and 70% of the ultimate load obtained by the authors in a previous study, respectively. The strain and deflection increased linearly within 5 days of applying the load and then leveled off. The pipe showed a slight increase in the crack width and deflection, indicating that fiber creep did not have a significant impact on the long-term performance of the concrete pipe. Also, it was observed that strain values surpassed those for plain concrete material, suggesting that including synthetic fiber in the concrete pipe mix enhanced the pipe ductility.
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El-Kashif, Khaled Farouk Omar, Abdel-Rahman Hazem, Mohamed Ahmed Rozik, and Hany Ahmed Abdalla. "Strengthening of deficient reinforced concrete columns subjected to concentric and eccentric loads." Advances in Structural Engineering 23, no. 7 (December 19, 2019): 1322–35. http://dx.doi.org/10.1177/1369433219895358.
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In this research, different techniques of repair of deficient reinforced concrete columns are compared. These include carbon fiber–reinforced polymer sheets, steel jackets, and reinforced concrete jackets. The experimental investigation includes testing of 16 deficient columns of dimensions 150 × 150 × 800 mm subjected to concentric and eccentric loading up to failure. Two main variables are considered: the load eccentricity and the strengthening technique. The experimental results showed that the three strengthening techniques used in this research significantly improved the ultimate load carrying capacity in all cases of loading. Also, in the two cases of concentric loading and big eccentricity of 150 mm, carbon fiber–reinforced polymer wrapping achieved the highest ductility and absorbed energy capacity. In addition, strengthening with reinforced concrete jacket improved the initial stiffness and toughness. The cracking load, ultimate load, and ductility of the deficient columns after strengthening were experimentally recorded and compared. The results can help the structural engineer to consider the most efficient method of repair for such columns.
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Hajro, Ismar, and Petar Tasić. "Properties mismatching and distribution on structural steels welded joints." Advanced Technologies & Materials 43, no. 2 (December 15, 2018): 15–20. http://dx.doi.org/10.24867/atm-2018-2-003.
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The paper presents results of combined, conventional and non-conventional, approach for evaluation of mechanical and technological properties of structural steel's welded joints. The selected structural steels are in the range of most common used strength level(s), as well as corresponding various chemical composition concept(s) and processing routes. A short review regarding weldability is presented based on recommendation provided in EN 1011-2, manufacturers recommendation, and own results. However, even it is a well-known fact, mismatching of properties is presented rather to provide sense of its level for particular steel grades. Moreover, the level of under-matching of weakest weld zone (coarse grained heat affected zone), provided by mean of welding thermo-cycle simulation is presented. This is due to the fact that such estimation is not possible with everyday conventional (standardized) testing. The most important design and technological properties of welded joint(s) are considered; e.g. strength, ductility, hardness, microstructure and toughness.
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Huang, Qunyi, John Orr, Yanxia Huang, Feng Xiong, and Hongyu Jia. "Seismic performance of a load-bearing prefabricated composite wall panel structure for residential construction." Advances in Structural Engineering 23, no. 13 (June 6, 2020): 2928–41. http://dx.doi.org/10.1177/1369433220927257.
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To improve both seismic performance and thermal insulation of low-rise housing in rural areas of China, this study proposes a load-bearing prefabricated composite wall panel structure that achieves appropriate seismic performance and energy efficiency using field-assembled load-bearing prefabricated composite wall panels. A 1:2 scale prototype built using load-bearing prefabricated composite wall panel is subjected to quasi-static testing so as to obtain damage characteristics, load-bearing capacity and load–displacement curves in response to a simulated earthquake. As a result, seismic performance indicators of load-bearing capacity, deformation and energy-dissipating characteristics, are assessed against the corresponding seismic design requirements for rural building structures of China. Experimental results indicate that the earthquake-resistant capacity of the prototype is 68% higher than the design value. The sample has a ductility factor of 4.7, which meets the seismic performance requirement mandating that the ductility factor of such concrete structures should exceed 3. The design can be further optimized to save the consumption of material. This shows that the load-bearing prefabricated composite wall panel structure developed here has decent load-bearing capacity, ductility and energy dissipation abilities, a combination of which is in line with the seismic design code. A new construction process proposed here based on factory prefabrication and field assembly leads to a considerable reduction of energy consumption.
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Ma, Yu, Gang Ji, Zhe Chen, Ahmed Addad, and Vincent Ji. "On the Study of a TiB2 Nanoparticle Reinforced 7075Al Composite with High Tensile Strength and Unprecedented Ductility." Materials Science Forum 941 (December 2018): 1933–38. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1933.
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Strength and ductility are the two most important mechanical properties of a structural material. However, they are often mutually exclusive. In this study, a 6 wt. % TiB2 nanoparticle reinforced 7075Al (i.e. TiB2/7075Al) composite was designed and produced by the processing route combining casting, friction stir processing, hot extrusion and T6 heat treatment. The result of tensile testing demonstrates that the as-processed composite sample presents an ultimate tensile strength of 677 MPa and a total elongation to failure of around 15 %, being higher than any Al or Al based materials ever reported. The typical microstructure contains the TiB2 reinforcement nanoparticles uniformly distributed in the equiaxed Al grain matrix (2 μm in average grain size). In addition to the dispersed nanoprecipitates of the 7075Al (Al-Zn-Mg-Cu) matrix, the integrated TiB2 nanoparticles are systematically decorated by a shell corresponding to (Zn1.5Cu0.5)Mg. This finding challenges our understanding and opens a door for further enhancing strength and ductility being easily scalable for industrial applications.
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Williams, Thomas R., Xuemeng Xia, Thomas E. Darby, and Stephen R. Sharp. "Evaluation of Stainless Steel Fasteners for Bolted Field Splice Connections of ASTM A1010 Corrosion-Resistant Steel Plate Girders." Transportation Research Record: Journal of the Transportation Research Board 2630, no. 1 (January 2017): 85–94. http://dx.doi.org/10.3141/2630-11.
Full textAbstract:
The Virginia Department of Transportation, Richmond, initiated this study to compare the mechanical properties, availability, and costs of stainless steel fastener materials for use with ASTM A1010 stainless steel plate. The investigation focused on fastener materials included in ASTM A193 and compared them with ASTM A325 bolts. The ASTM A193 bolts tested were the B6, B8, and B8M. Test results indicated that the ASTM A193 B8 fasteners provided the most economic combination of mechanical strength, corrosion resistance, and cost. Uniaxial tension tests and Skidmore–Wilhelm rotational capacity tests revealed that the B6 fasteners had high strength but lower ductility, whereas the B8M fasteners had lower strength but higher ductility. The B8 fastener had an ideal combination of strength and ductility. The mechanical performance of the ASTM A193 fasteners was improved further by the use of hardened washers. Because the bolts are hot forged, sensitization, which can reduce corrosion resistance, was of concern. Standard testing indicated that the B8 and B8M as-received bolts were unsensitized. The cost of the B8 fasteners compared favorably with that of other stainless steel fasteners. Further, the B8 fasteners are available from manufacturers that comply with Buy America requirements. The cost of stainless steel fasteners is higher than that of ASTM A325 steel fasteners. As their use increases, however, larger orders may help reduce prices. The initial research indicates that stainless fasteners could be a structurally sound option to use to build reduced maintenance bridges.
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Mashal, Mustafa, Samuel White, and Alessandro Palermo. "Quasi-static cyclic testing of emulative cast-in-place connections for Accelerated Bridge Construction in seismic regions." Bulletin of the New Zealand Society for Earthquake Engineering 49, no. 3 (September 30, 2016): 267–82. http://dx.doi.org/10.5459/bnzsee.49.3.267-282.
Full textAbstract:
This paper presents findings from the first phase of testing at the University of Canterbury on seismic performance of emulative connections for Accelerated Bridge Construction (ABC) in regions of moderate to high seismicity. Emulative connections between precast concrete elements aim to target similar seismic behaviour as traditional ductile monolithic construction. The emulative solution in this research is called “High Damage Connection” (HDC).
HDCs intend to achieve similar levels of seismic performance and ductility in a precast column as that can be expected of a monolithic one. HDC relies on formation of plastic hinges in the precast column during a design level earthquake to emulate monolithic ductile behaviour.
Two types of HDCs, the grouted duct connection and member socket connection, were investigated in this research. Four half-scale precast segmental columns were constructed. Two columns featured grouted duct connections as the primary connection type. The other two columns used member socket connections. For a better understanding of the connection response under severe lateral loading, both uniaxial and biaxial testing of the columns was carried out.
In this paper, an introduction to each connection type followed by design procedure, detailing considerations and construction methodology are explained in detail. Testing results and observations of seismic performance for each connection are thoroughly presented. The research concludes that High Damage Connections have good potential for ABC in regions of moderate to high seismicity. The connections that were tested achieved good levels of energy dissipation and ductility with similar performance to conventional monolithic connections.
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Khalili, Pooria, Mikael Skrifvars, and Ahmet Semih Ertürk. "Fabrication: Mechanical Testing and Structural Simulation of Regenerated Cellulose Fabric Elium® Thermoplastic Composite System." Polymers 13, no. 17 (August 31, 2021): 2969. http://dx.doi.org/10.3390/polym13172969.
Full textAbstract:
Regenerated cellulose fibres are an important part of the forest industry, and they can be used in the form of fabrics as reinforcement materials. Similar to the natural fibres (NFs), such as flax, hemp and jute, that are widely used in the automotive industry, these fibres possess good potential to be used for semi-structural applications. In this work, the mechanical properties of regenerated cellulose fabric-reinforced poly methyl methacrylate (PMMA) (Elium®) composite were investigated and compared with those of its natural fibre composite counterparts. The developed composite demonstrated higher tensile strength and ductility, as well as comparable flexural properties with those of NF-reinforced epoxy and Elium® composite systems, whereas the Young’s modulus was lower. The glass transition temperature demonstrated a value competitive (107.7 °C) with that of other NF composites. Then, the behavior of the bio-composite under bending and loading was simulated, and a materials model was used to simulate the behavior of a car door panel in a flexural scenario. Modelling can contribute to predicting the structural behavior of the bio-based thermoplastic composite for secondary applications, which is the aim of this work. Finite element simulations were performed to assess the deflection and force transfer mechanism for the car door interior.
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Hao, Yifei, Hong Hao, Yanchao Shi, Zhongqi Wang, and Ruiqing Zong. "Field Testing of Fence Type Blast Wall for Blast Load Mitigation." International Journal of Structural Stability and Dynamics 17, no. 09 (October 23, 2017): 1750099. http://dx.doi.org/10.1142/s0219455417500997.
Full textAbstract:
To protect structures from external explosions, solid protective barriers have been demonstrated by experimental and numerical studies to be able to effectively mitigate blast loads on structures behind them. However, to protect against blast loads, barriers normally need to be designed to have high structural resistance and ductility. This often requires bulky and heavy protective barriers which are not only highly costly but also often not appropriate for application in downtown areas as they are not friendly to city planning or appearance. Fence type blast wall consisting of structural columns was recently proposed and its effectiveness in mitigating blast loads was investigated through numerical simulations. It was found that the wave–fence interaction and interference of waves significantly reduced the wave energy when the blast wave passed through the fence blast wall. To further investigate the effectiveness and applicability of fence type blast wall as a highly potential technology for structural protection in an urban area, field tests have been conducted and results are reported in this paper. Columns with circular and triangular cross-sections were adopted to build fence blast walls. In addition, a masonry wall was also constructed as solid barrier for comparison. Hemispherical TNT explosive weighing 1.0 kg with different stand-off distances was detonated on the ground to generate the blast load. Blast overpressures in free air, behind the fence blast wall and behind the masonry wall were recorded by pressure sensors. The effectiveness of the fence blast wall in reducing blast wave and protecting structures was demonstrated by the test data.
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Morris, Gareth J., Desmond K. Bull, and Brendon A. Bradley. "In situ conditions affecting the ductility capacity of lightly reinforced concrete wall structures in the Canterbury earthquake sequence." Bulletin of the New Zealand Society for Earthquake Engineering 48, no. 3 (September 30, 2015): 190–203. http://dx.doi.org/10.5459/bnzsee.48.3.190-203.
Full textAbstract:
Following the 2010-2011 Canterbury (New Zealand) earthquake sequence, lightly reinforced wall structures in the Christchurch central business district were observed to form undesirable crack patterns in the plastic hinge region, while yield penetration either side of cracks and into development zones was less than predicted using empirical expressions. To some extent this structural behaviour was unexpected and has therefore demonstrated that there may be less confidence in the seismic performance of conventionally designed reinforced concrete (RC) structures than previously anticipated. This paper provides an observation-based comparison between the behaviour of RC structural components in laboratory testing and the unexpected structural behaviour of some case study buildings in Christchurch that formed concentrated inelastic deformations. The unexpected behaviour and poor overall seismic performance of ‘real’ buildings (compared to the behaviour of laboratory test specimens) was due to the localization of peak inelastic strains, which in some cases has arguably led to: (i) significantly less ductility capacity; (ii) less hysteretic energy dissipation; and (iii) the fracture of the longitudinal reinforcement. These observations have raised concerns about whether lightly reinforced wall structures can satisfy the performance objective of “Life Safety” at the Ultimate Limit State. The significance of these issues and potential consequences has prompted a review of potential problems with the testing conditions and procedures that are commonly used in seismic experimentations on RC structures. This paper attempts to revisit the principles of RC mechanics, in particular, the influence of loading history, concrete tensile strength, and the quantity of longitudinal reinforcement on the performance of real RC structures. Consideration of these issues in future research on the seismic performance of RC might improve the current confidence levels in newly designed conventional RC structures.
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Lin, Huang-bin, Shou-gao Tang, and Cheng Lan. "Control Parametric Analysis on Improving Park Restoring Force Model and Damage Evaluation of High-Strength Structure." Advances in Materials Science and Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/3696418.
Full textAbstract:
In the dynamic time-history analysis of structural elastoplasticity, it is important to develop a universal mathematical model that can describe the force-displacement characteristics for restoring force. By defining three control parameters (stiffness degradation, slip closureγ, energy degradationβ), the Park restoring force mathematical model can simulate various components. In this study, the Park restoring force has been improved by adding two control parameters (energy-based strength degradationβeand ductility-based strength degradationβd). Based on the testing data, the constitutive model is input and 55 numerical models are developed to analyze the effects of various parameters on structural behavior.Conclusion. (1)βhas determinative effect on structural behavior; the effect ofβeis basically consistent with that ofβ;αhas significant effect on shear forces and bending moments;γhas significant effect on displacements and accelerations;βdhas significant effect on shearing forces, acceleration, and total energy consumptions. (2) Based on the classification of four types of damage level, the recommended values forα,γ,β,βe, andβdare presented. (3) Based on the testing data of high-strength columns, the recommended values for the five control parameters of the improved Park restoring force model are presented.
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Megget, Leslie M. "The seismic behaviour of small reinforced concrete beam-column knee joints." Bulletin of the New Zealand Society for Earthquake Engineering 31, no. 4 (December 31, 1998): 215–45. http://dx.doi.org/10.5459/bnzsee.31.4.215-245.
Full textAbstract:
The majority of research into beam-column knee joints has been conducted with monotonic loading. Many of these joints failed to reach their member moment capacity, especially under opening moments, while a few cyclic knee joint tests have been completed in the United States this decade. This paper describes the cyclic testing of 8 small knee joints designed to the 1995 New Zealand Concrete Standard. In addition two joints designed and detailed to the 1965 N.Z. Concrete Code were also tested. Joints with U-bar anchorages performed better than joints with standard 90 degree hook details on beam and column bars. The current Concrete Standard (NZS3101:1995) designs usually attained their nominal moment capacity in both directions up to and including ductility 4 displacements, but subsequently strengths fell off at higher ductilities. Joints with extra diagonal bars across the inner comer were able to sustain their nominal member strengths to higher ductility levels, especially under opening moments. A maximum horizontal joint shear stress of 0.12 f’c, for knee joints, in ductile frame buildings is recommended, where this limit is 60% of the current NZS3101:1995 Standard recommendation. An approximate 25% degradation of the joint shear stress occurred as displacement ductility factors increased from 1 to 8. The 1960's designed joints behaved poorly, as expected, with joint shear and anchorage failures occurring, in both moment directions, at strength levels below the beam's nominal strength. A maximum joint shear stress of only 0.072 f’c was reached and this fell to about a third of that stress between displacement ductility factors of 1 and 4 under closing moments.
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Hong, Won-Kee, and Hee-Cheul Kim. "Behavior of concrete columns confined by carbon composite tubes." Canadian Journal of Civil Engineering 31, no. 2 (February 1, 2004): 178–88. http://dx.doi.org/10.1139/l03-078.
Full textAbstract:
The carbon composite tube can play an important role in replacing or complementing longitudinal and transverse reinforcing steels by providing ductility and strength for conventional columns. In this study, both experimental and analytical investigations of axial behavior of large-scale circular and square concrete columns confined by carbon composite tubes are presented. The specimens are filament-wound carbon composite with 90° + 90°, 90° ± 60°, 90° ± 45°, and 90° ± 30° winding angles with respect to a longitudinal axis of a tube. The instrumented large-scale concrete-filled composite tubes are subjected to monotonic axial loads exerted by a 10 000 kN universal testing machine (UTM). The influence of transverse dilation, winding angle, thickness of a tube, as well as shape of the column section on stress–strain relationships of the confined columns is identified and discussed. Proposed equations to predict both strength and ductility of confined columns by carbon composite tubes demonstrate good correlation with test data obtained from large-scale specimens.Key words: carbon composites, glass fibers, strength, filament winding.
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Menegon, Scott J., John L. Wilson, Nelson TK Lam, and Emad F. Gad. "Experimental assessment of the ultimate performance and lateral drift behaviour of precast concrete building cores." Advances in Structural Engineering 23, no. 12 (May 11, 2020): 2597–613. http://dx.doi.org/10.1177/1369433220919077.
Full textAbstract:
Precast concrete building cores are a widely used lateral load resisting system in low and mid-rise multi-storey buildings. However, despite their widespread use in countries like Australia or New Zealand, a very little research or experimental testing has been undertaken to assess their lateral drift behaviour. This article will present the findings and observations of a recent experimental testing programme into reinforced concrete precast building cores, which included three large-scale ‘box-shaped’ precast building core specimens. Adjacent panels in each specimen were connected together using welded stitch plate connections and then connected to foundation blocks on the top and bottom using grout tube connections. The results of the testing showed that the welded stitch plate connections were too flexible to allow full composite action to be developed in the cross-section, which meant the precast building core specimens were around 25% more flexible than an equivalent cast in-situ version. The testing also highlighted common detailing and construction deficiencies that can severely inhibit the ductility of the core.
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Johanides, Marek, Antonin Lokaj, David Mikolasek, Petr Mynarcik, Pavel Dobes, and Oldrich Sucharda. "Timber Semirigid Frame Connection with Improved Deformation Capacity and Ductility." Buildings 12, no. 5 (April 30, 2022): 583. http://dx.doi.org/10.3390/buildings12050583.
Full textAbstract:
The present study deals with the innovation and the possibilities of improving the design solution of a frame connection for two selected types of fasteners. All specimens were made of glued laminated timber. Dowel-type mechanical fasteners, a combination of bolts and dowels, and full-threaded screws were used for the connection. The main goal of this research was to replace the typical solution (common dowel-type fasteners) with a more modern, faster, and easier solution in order to improve the load-carrying capacity, ductility, and deformation capacity of this type of frame connection. This article also aimed to provide a detailed evaluation of the mechanical properties of the used glued laminated timber and fasteners in order to comprehensively evaluate the research task. For the design solution, a frame connection created from a system of two struts and a partition was chosen as the basis of the experimental program. Dowel-type mechanical fasteners, as well as combinations of bolts and dowels, were used for the connection; however, in addition to these standardly used mechanical fasteners, full-threaded screws were used. The article describes the use of static destructive testing to determine the ductility of the connection, considering different variations in the strengthening of the individual segments of the mentioned connection means. In the first variation, the individual components of the frame were not reinforced in any way. In the second, the crossbar was reinforced with two full-threaded bolts. In the third, the webs and the crossbar were reinforced with two full-threaded bolts. In the article, these ductility values were compared with each other and the procedure was set by the currently valid standard.
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Xie, Pan, T. Yu, Y. L. Wong, and J. G. Teng. "Compressive Behavior of Large-Scale Hybrid FRP-Concrete-Steel Double-Skin Tubular Columns." Advanced Materials Research 243-249 (May 2011): 1138–44. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1138.
Full textAbstract:
Hybrid FRP-concrete-steel double-skin tubular columns (DSTCs) are a new form of hybrid structural members. A hybrid DTSC consists of an inner steel tube, an outer FRP tube and a concrete infill between them. Hybrid DSTCs possess many important advantages over conventional structural members, including their excellent corrosion resistance as well as excellent ductility and seismic resistance. A large amount of research has been conducted on hybrid DSTCs, but the existing experimental studies have been limited to the testing of small-scale columns. This paper presents preliminary results from the first series of large-scale axial compression tests on hybrid DSTCs, which forms part of a larger experimental study currently under way at The Hong Kong Polytechnic University. These test results confirm the excellent axial compressive response of hybrid DSTCs as initially expected.
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Bahia, Hussain U., Dario Perdomo, and Pamela Turner. "Applicability of Superpave Binder Testing Protocols to Modified Binders." Transportation Research Record: Journal of the Transportation Research Board 1586, no. 1 (January 1997): 16–23. http://dx.doi.org/10.3141/1586-03.
Full textAbstract:
An effort is made to summarize current practices for modifying paving asphalts. The types and classes of modifiers used, or considered, for paving applications are reviewed. The applicability of the Superpave binder specification (AASHTO MP1) is reviewed critically, and the modified-asphalt characteristics that are not considered in this specification are evaluated. Conventional testing results of modified binders are compared with Superpave testing results. The results indicate that a variety of additives can be classified, on the basis of their composition and their effects on asphalts, as polymers (elastomeric and plastomeric), fillers, fibers, hydrocarbons, antistripping agents, oxidants, antioxidants, crumb rubber, and extenders. These additives vary significantly in their physical and chemical characteristics and are expected to have widely variable effects on performance-related properties of asphalts. The assumptions supporting the criteria in the Superpave binder specification may not be valid for some modified binder systems. Furthermore, the testing protocols included in the specification do not consider certain important characteristics that are typical of particular modified binders. Among these characteristics are strain dependency, thixotropy, loading-rate dependency, and time-temperature equivalency. Conventional measurements used currently by state departments of transportation such as ductility, elastic recovery, and resilience, were collected. The ranking of five modified systems on the basis of conventional and Superpave measurements was analyzed. The analysis does not indicate that the conventional test methods are consistent in their rankings, nor does it indicate that these measures add much to the information deduced from the Superpave data.
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Vijayalakshmi, Ramalingam, and Srinivasan Ramanagopal. "Experimental Investigation Into Banana Fibre Reinforced Lightweight Concrete Masonry Prism Sandwiched with GFRP Sheet." Civil and Environmental Engineering Reports 30, no. 2 (June 1, 2020): 15–31. http://dx.doi.org/10.2478/ceer-2020-0017.
Full textAbstract:
AbstractThis paper presents the stress-strain behaviour of Natural Banana microfibre reinforced Lightweight Concrete (LWC) prisms under axial compression. The compressive strength of masonry is obtained by testing stack bonded prisms under compression normal to its bed joint. LWC blocks of cross-sectional dimensions 200 mm x 150 mm were used to construct the prism with an overall height of 630 mm. Three series of specimens were cast; (a) prism without Banana fibre (control), (b) prism with Banana microfibres, (c) prism with Banana microfibres sandwiched with Glass Fibre Reinforced Polymer (GFRP) sheets. Natural Banana fibres were used as structural fibre reinforcement at different volume fractions (VF). The results indicate that the presence of fibres helps to improve the strength, stiffness, and ductility of LWC stack bonded prisms under compression. The test results also indicate that banana fibre reinforcement provides an improved crack bridging mechanism at both micro and macro levels. The GFRP sandwiched prism specimens exhibited excellent ductility and load-carrying capacity resulting from improved plastic deformation tolerance under compression and bonding between the LWC block and GFRP sheet.
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Skakov, Mazhyn, Yernat Kozhakhmetov, Nurya Mukhamedova, Arman Miniyazov, Igor Sokolov, Azamat Urkunbay, Gainiya Zhanbolatova, and Timur Tulenbergenov. "Effect of a High-Temperature Treatment on Structural-Phase State and Mechanical Properties of IMC of the Ti-25Al-25Nb at.% System." Materials 15, no. 16 (August 12, 2022): 5560. http://dx.doi.org/10.3390/ma15165560.
Full textAbstract:
In this research, samples of an alloy with a bimodal structure were studied on the basis of a previously developed technology for obtaining hydrogen storage materials based on the Ti-Al-Nb system. The results of SPS of mechanically activated powder mixtures of the Ti-Al-Nb system at a temperature of 1300 °C make it possible to obtain an alloy with a predominantly bimodal structure. However, an insignificant presence of TiAl3, AlNb2 phases, and unreacted niobium is still observed in the structure. The mechanical properties of alloys of the Ti-Al-Nb system after sintering show abnormally low values of strength and ductility (less than 150 MPa). Two-stage heat treatment of alloys of the Ti-Al-Nb system leads to the decomposition of large precipitates of TiAl3 with the formation of O-phase nuclei, as well as to the complete dissolution of unreacted niobium and AlNb2 phases. Heat treatment of alloys of the Ti-Al-Nb system contributes to an increase in its strength by approximately 10 times (1310 MPa, MA-180), and ductility by 2 times (1322 MPa, MA-20). The surface fracture of samples obtained after testing is characterized by intergranular (intercrystalline) brittle fracture with “river” or “step” features.
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Daniel, Torrealva, and Arzapalo Joel. "Experimental testing on the structural capacity of coupling beams with non-anchored longitudinal rebars." MATEC Web of Conferences 364 (2022): 04017. http://dx.doi.org/10.1051/matecconf/202236404017.
Full textAbstract:
Coupling beams are structural elements which connect shear walls to improve the lateral stiffness and allow to transfer shear forces, while possessing sufficient ductility to dissipate the energy produced due to the lateral displacement. An error in the construction of a 16-story buildings resulted in that only the bottom layer of the longitudinal reinforcement bars in all coupled beams are anchored into the lateral walls, the upper longitudinal bars are cut before anchored to the lateral walls. The reconstruction of all coupled beams in the building is technical and economically non-feasible therefore, to propose a more efficient and less costly retrofit procedure, an experimental study is undertaken to analyze the real structural capacity of these coupling beams. Carbon fiber reinforced polymer (CFRP) is chosen as the reinforcement material for the upper part of the beams. A total of three specimens are tested, two of them under cyclic quasi-static load to determine the flexural capacity of the cross section in the interface wall-coupling beam, and one of them under monotonic loading to determine the shear capacity of the cracked cross section. The results of the cyclic test showed a very limited contribution of the CFRP in the flexural capacity when the fiber is in tension. However, the flexural behavior of the section with the lower reinforcement in tension is not affected by the upper non-anchored bars and showed a flexural capacity and energy dissipation according to the existing rate of the steel reinforcement. The experimental results are used to develop a finite element model which reproduce the structural behavior of the beams with the construction error.
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Shaheen, Yousry B. I., and Essam A. Eltehawy. "Structural behaviour of ferrocement channels slabs for low cost housing." Challenge Journal of Concrete Research Letters 8, no. 2 (July 1, 2017): 48. http://dx.doi.org/10.20528/cjcrl.2017.02.002.
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This paper presents a new pre cast U-shape ferrocement forms reinforced with various types of metallic and non-metallic mesh reinforcement. This research was designed to investigate the feasibility and effectiveness of employing various types of reinforcing meshes in the construction of structural slabs incorporating permanent U-shape ferrocement forms as a viable alternative for conventional reinforced concrete slabs. Fiber glass meshes reinforcement was used for durability and protection against corrosion of reinforcing steel. To accomplish this objective, an experimental program was conducted. The experimental program comprised casting and testing ten slabs having the total dimensions of 500x100x2500 mm incorporating 40 mm thick U-shape permanent ferrocement forms. Series A consists of two conventionally reinforced concrete slabs were cast and tested and used as control slab without fibers and with fibers, volume fraction, 2.05 % and 2.177 %. Series B comprises of two slabs reinforced with one and two layers of expanded steel mesh, volume fraction 2.09 and 2.42% respectively. Series C comprises two slabs reinforced with two and four layers of welded galvanized steel mesh, having volume fraction 2.05 and 2.189% respectively. Series D Consists of two slabs reinforced with one layer and two layers of fiber glass meshes, having volume fraction 2.107 and 2.277% respectively. Series E comprises two slabs reinforced with 2 layers expanded steel mesh and one layer expanded steel mesh, having volume fraction 1.357 and 2.750 % respectively. The test specimens were tested as simple slabs under four-line loadings condition on a span of 2300mm. The performance of the test slabs in terms of strength, stiffness, strains, cracking behavior, ductility, and energy absorption properties was investigated. The behavior of the developed slabs was compared to that of the control slabs. The experimental results showed that high ultimate and serviceability loads, better crack resistance control, high ductility, and good energy absorption properties could be achieved by using the proposed slabs and low cost compared with control specimen.
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Mousseau, Sébastien, Patrick Paultre, and Jacky Mazars. "Seismic performance of a full-scale, reinforced high-performance concrete building. Part II: Analytical study." Canadian Journal of Civil Engineering 35, no. 8 (August 2008): 849–62. http://dx.doi.org/10.1139/l08-019.
Full textAbstract:
Full-scale tests provide valuable information on the characteristics of building structures that can be used to evaluate design methods, to calibrate modelling techniques, and to determine damage corresponding to loading levels. These tests are scarce due to the enormous requirements in testing space and specialized testing equipment. The seismic behaviour of a full-scale, two-storey, reinforced high-performance concrete building designed with moderate ductility detailing is evaluated by pseudo-dynamic testing, during which increasing seismic loads are applied, resulting in increasing levels of permanent damage to the structure. This paper presents the analytical predictions of the test results using a global force–displacement parameters approach and a refined approach, half-way between global modelling and finite element modelling, using force–strain parameters and damage mechanics principles. Identification of the parameters required to describe the response parameters are presented together with a description of the numerical procedures used in each approach. It is shown that the predictions are in good agreement with the test results. Advantages and disadvantages of each approach are highlighted in the context of performance-based analysis and design.
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Sambucci, Matteo, Abbas Sibai, Luciano Fattore, Riccardo Martufi, Sabrina Lucibello, and Marco Valente. "Finite Element Multi-Physics Analysis and Experimental Testing for Hollow Brick Solutions with Lightweight and Eco-Sustainable Cement Mix." Journal of Composites Science 6, no. 4 (April 5, 2022): 107. http://dx.doi.org/10.3390/jcs6040107.
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Combining eco-sustainability and technological efficiency is one of the “hot” topics in the current construction and architectural sectors. In this work, recycled tire rubber aggregates and acoustically effective fractal cavities were combined in the design, modeling, and experimental characterization of lightweight concrete hollow bricks. After analyzing the structural and acoustic behavior of the brick models by finite element analysis as a function of the type of constituent concrete material (reference and rubberized cement mixes) and hollow inner geometry (circular- and fractal-shaped hollow designs), compressive tests and sound-absorption measurements were experimentally performed to evaluate the real performance of the developed prototypes. Compared to the traditional circular hollow pattern, fractal cavities improve the mechanical strength of the brick, its structural efficiency (strength-to-weight ratio), and the medium–high frequency noise damping. The use of ground waste tire rubber as a total concrete aggregate represents an eco-friendlier solution than the ordinary cementitious mix design, providing, at the same time, enhanced lightweight properties, mechanical ductility, and better sound attenuation. The near-compliance of rubber-concrete blocks with standard requirements and the value-added properties have demonstrated a good potential for incorporating waste rubber as aggregate for non-structural applications.
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Khattak, Nouman, Moustafa Mansour, Tamer El-Maaddawy, and Najif Ismail. "Continuous Reinforced Concrete Beams Strengthened with Fabric-Reinforced Cementitious Matrix: Experimental Investigation and Numerical Simulation." Buildings 12, no. 1 (December 31, 2021): 27. http://dx.doi.org/10.3390/buildings12010027.
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This paper aims to examine the nonlinear flexural behavior of continuous RC beam specimens strengthened with fabric-reinforced cementitious matrix (FRCM) composites through experimental testing and numerical modeling. A total of nine two-span RC beam specimens were constructed and tested. Test parameters included the type of FRCM (carbon (C-FRCM) and polyparaphenylene benzobisoxazole (PBO-FRCM)), location of strengthening (sagging and hogging regions) and number of FRCM layers (two and four layers). Test results indicated that sagging strengthening resulted in a strength gain in the range of 17 to 29%, whereas hogging strengthening increased the load capacity by 9 to 17%. The use of C-FRCM resulted in a higher strength gain than that provided by PBO-FRCM composites. Specimens strengthened with PBO-FRCM exhibited, however, higher ductility and deformational capacity than those of their counterparts strengthened with C-FRCM. Doubling the number of FRCM layers resulted in no or insignificant increase in the load capacity but reduced the beam ductility. Specimens strengthened in the sagging regions exhibited moment redistribution ratios of 13 to 26% between the hogging and sagging regions. Insignificant moment redistribution was recorded for the specimens strengthened in the hogging region. Three-dimensional (3D) numerical simulation models, with and without an interfacial bond-slip law at the fabric–matrix interface, were developed. The inclusion of the bond-slip law in the modeling had an insignificant effect on predicted response. Although the models tended to underestimate the deflection, the predicted load capacities were within a 12% error band. Numerical findings were in agreement with those obtained from laboratory testing.
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Xia, Yingjie, Qingkun Meng, Chuanqing Zhang, Ning Liu, Zhenxing Zhao, Jun Chen, and Gao Yang. "Application of 3D Printing Technology in the Mechanical Testing of Complex Structural Rock Masses." Geofluids 2021 (October 13, 2021): 1–23. http://dx.doi.org/10.1155/2021/7278131.
Full textAbstract:
In the engineering of underground construction, the discontinuous structures in rock mass have important influences on the mechanical behaviors of the subsurface of rock mass. The acquisition of mechanical parameters is the basis of rock mass engineering design, construction, safety, and stability evaluation. However, the mechanical parameters and failure characteristics of the same rock mass under different mechanical conditions cannot be obtained due to the limitations of specimen preparation techniques. In recent years, with the continuous development of 3D printing (3DP) technology, it has been successfully applied to the repetitive preparation of rock mass samples. The combinations of 3DP and other techniques, such as 3D scanning and CT scanning, provided a new approach to study the mechanical behavior of complex structural rock masses. In this study, through a comprehensive review of the technical progress, equipment situation, application fields, and challenges of the use of 3DP technology, the following conclusions were obtained: (1) 3DP technology has advantages over traditional rock mass specimen preparation techniques, and the verification of test results using 3D printed samples shows that the 3DP has broad application prospects in geotechnical engineering. (2) The combination of 3DP and other advanced techniques can be used to achieve the accurate reconstruction of complex structural rock masses and to obtain the mechanical and failure characteristics of the same rock mass structure under different mechanical boundary conditions. (3) The development of 3DP materials with high strength, high brittleness, and low ductility has become the major bottleneck in the application of 3DP in geotechnical engineering. (4) 3D printers need to meet the high precision and large size requirements while also having high strength and long-term printing ability. The development of 3D printers that can print different types of materials is also an important aspect of the application of 3DP in geotechnical engineering.
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Xia, Yingjie, Qingkun Meng, Chuanqing Zhang, Ning Liu, Zhenxing Zhao, Jun Chen, and Gao Yang. "Application of 3D Printing Technology in the Mechanical Testing of Complex Structural Rock Masses." Geofluids 2021 (October 13, 2021): 1–23. http://dx.doi.org/10.1155/2021/7278131.
Full textAbstract:
In the engineering of underground construction, the discontinuous structures in rock mass have important influences on the mechanical behaviors of the subsurface of rock mass. The acquisition of mechanical parameters is the basis of rock mass engineering design, construction, safety, and stability evaluation. However, the mechanical parameters and failure characteristics of the same rock mass under different mechanical conditions cannot be obtained due to the limitations of specimen preparation techniques. In recent years, with the continuous development of 3D printing (3DP) technology, it has been successfully applied to the repetitive preparation of rock mass samples. The combinations of 3DP and other techniques, such as 3D scanning and CT scanning, provided a new approach to study the mechanical behavior of complex structural rock masses. In this study, through a comprehensive review of the technical progress, equipment situation, application fields, and challenges of the use of 3DP technology, the following conclusions were obtained: (1) 3DP technology has advantages over traditional rock mass specimen preparation techniques, and the verification of test results using 3D printed samples shows that the 3DP has broad application prospects in geotechnical engineering. (2) The combination of 3DP and other advanced techniques can be used to achieve the accurate reconstruction of complex structural rock masses and to obtain the mechanical and failure characteristics of the same rock mass structure under different mechanical boundary conditions. (3) The development of 3DP materials with high strength, high brittleness, and low ductility has become the major bottleneck in the application of 3DP in geotechnical engineering. (4) 3D printers need to meet the high precision and large size requirements while also having high strength and long-term printing ability. The development of 3D printers that can print different types of materials is also an important aspect of the application of 3DP in geotechnical engineering.
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Funahashi, Miki, and Walter T. Young. "Cathodic Protection of Prestressed Bridge Members—Full-Scale Testing." Transportation Research Record: Journal of the Transportation Research Board 1561, no. 1 (January 1996): 13–25. http://dx.doi.org/10.1177/0361198196156100103.
Full textAbstract:
The results of a study on the use of cathodic protection on prestressed and post-tensioned concrete bridge members are summarized. Previous laboratory tests to evaluate hydrogen embrittlement of high strength steel embedded in concrete have proven that cathodic protection will generate hydrogen on high-strength steel in concrete if the potential is more negative than the thermodynamic hydrogen evolution potential. The hydrogen generated will enter the steel and cause a loss in ductility that will adversely affect the steel's performance if a notch is present. Full-scale beams were constructed to further study those phenomena. Four pretensioned beams were constructed. In addition, two post-tensioned slabs were constructed to evaluate cathodic protection of anchorages and tendons encased in metal or plastic conduits. Cathodic protection currents were supplied by IR drop-free potential controlled rectifiers. Good potential control at control points was achieved by using externally mounted silver-silver chloride reference electrodes and a conductive gel bridge. However, inconsistent potential control occurred at locations other than at the control points. Later in the study, constant current power supplies were used on two of the beams. Hydrogen entering the steel as the result of corrosion appears to have masked the presence of hydrogen that might have been produced by cathodic protection. The analysis also revealed that there was corrosion of some pretensioned wires at crossings with interior steel reinforcing bars due to interference (stray current) caused by cathodic protection application. Analysis of the post-tensioned slabs indicated little effect of cathodic protection on tendons inside plastic or metal ducts from the application of cathodic protection. Beneficial effects were noted on anchor points where mortar was in contact with the metal.
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Kováčová, A., T. Kvačkaj, R. Bidulský, J. Bidulská, R. Kočiško, J. Dutkiewicz, and L. Lityńska-Dobrzyńska. "Investigation of the Ultrafine-Grained Structure Formation under Different Strain Rates." Archives of Metallurgy and Materials 62, no. 2 (June 1, 2017): 851–56. http://dx.doi.org/10.1515/amm-2017-0125.
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AbstractThe present paper deals with a study on formation of specific substructural features in OFHC copper processed by equal-channel angular pressing (ECAP) considering different strain rate conditions. Since two mechanical tensile testing equipments were being used, strain rate response could be studied in a wide range (both in static and dynamic regimes). Moreover, the copper before tensile testing was subjected to drawing and ECAP, separately, which allows to study the influence of both structural and substructural features (CG vs. UFG structure). Considering the static regime, it was found that UFG materials have advanced properties, showing higher strength and ductility in comparison to their CG counterparts. However, this is valid only to the critical value of the strain rate. In the dynamic regime, mathematical linearized results imply that ultimate tensile strength in samples processed by ECAP increases twice every 10 s−1rising, however, they lost approximately the same plastic properties than samples after drawing. Differences in the progress of mechanical properties are related to specific structural and substructural features evolved in the material during ECAP processing. Above mentioned features were studied in detail by methods of transmission and scanning electron microscopy (TEM, SEM).
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Tayyaba, Qanita, Adnan Qayyum Butt, Muhammad Shahzad, and Tahir Ali. "Simultaneous improvement of corrosion and mechanical properties of AA 5083 aluminum alloy." Metallurgical and Materials Engineering 28, no. 2 (June 30, 2022): 319–34. http://dx.doi.org/10.30544/809.
Full textAbstract:
In this study, the effects of cold-rolling and annealing on the structural, electrochemical, and mechanical properties of AA5083 in a simulated seawater environment are investigated. The results demonstrated that annealing temperature significantly affects the alloy's mechanical and corrosion properties. According to potentiodynamic results, the rate of corrosion decreased after annealing. Compared to the cold-rolled sample, the heat treatment doubles the electrochemical impedance, indicating that the corrosion resistance of AA5083 alloy is suitable at 50°C annealing. Approximately twice as much ductility was added to the materials as compared to the as-received materials. Additionally, the mechanical testing revealed the Portevin-Le Chatelier (PLC) Effect Type B band, which reflected the smaller grain size.