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Journal articles on the topic 'End anchorage length'
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1
Gora, Abdurra’uf Mukhtar, Jayaprakash Jaganathan, Mohammed Parvez Anwar, and Hau Y. Leung. "Flexural capacity of bi-directional GFRP strengthened RC beams with end anchorages." International Journal of Structural Integrity 10, no. 2 (2019): 188–207. http://dx.doi.org/10.1108/ijsi-04-2018-0021.
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Purpose The purpose of this paper is to present the results of experimental and theoretical studies on the flexural capacity of reinforced concrete (RC) beams strengthened using externally bonded bi-directional glass fibre reinforced polymer (GFRP) composites and different end anchorage systems. Design/methodology/approach A series of nine RC beams with a length of 1,600 mm and a cross-section of 200 mm depth and 100 mm width were prepared and externally strengthened in flexure with bi-directional GFRP composites. These strengthened beams were anchored with three different end anchorage systems namely closed GFRP wraps, GFRP U-wraps and mechanical anchors. All these beams were tested with four-point bending system up to failure. The experimental results are compared with the theoretical results obtained using the relevant design guidelines. Findings The experimental results demonstrate a significant increase in the flexural performance of the GFRP strengthened beams with regard to the ultimate load carrying capacity and stiffness. The results also show that GFRP strengthened beams without end anchorages experienced intermediate concrete debonding failure at the GFRP plate end, whereas all the GFRP strengthened beams with different end anchorage systems failed in rupture of GFRP with concrete crushing. The theoretical results revealed no significant difference among the relevant design guidelines with regard to the predicted ultimate moment capacities of the bi-directional GFRP strengthened RC beams. However, the results show that ACI Committee 440 Report (2008) design recommendation provides reasonably acceptable predictions for the ultimate moment capacities of the tested beams strengthened externally with bi-directional GFRP reinforcement followed by FIB Bulletin 14 (2001) and eventually by JSCE (1997). Originality/value The research work presented in this manuscript is authentic and could contribute to the understanding of the overall behaviour of RC beams strengthened with FRP and different end anchorage systems under flexural loading.
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Zou, Lan Lin, and Xing Lin Zhou. "Experimental Study on Strengthened Bridge Structures with Carbon Fiber Plate." Advanced Materials Research 284-286 (July 2011): 997–1000. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.997.
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In order to analyze the impact of anchor length, ends anchorage measures, strength of concrete, shear-span ratio, reinforcement ratio and the amount of carbon fiber plate on the bearing capacity of strengthened bridge structures with carbon fiber plate, 11 pieces of rectangle beams are fabricated for flexural experimental study. The experimental results show that the ultimate bearing capacity of the specimens increase different degree as different strengthened schemes: the bearing capacity of rectangle beams with plate end anchorage has increased remarkably; The beams have greater bearing capacity with more anchorage length in contrast to those without any anchorage measure; The ultimate bearing capacity enhanced more prominent for those specimens with low shear-span ratio and low reinforcement ratio.
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Wagner, Juliane, and Manfred Curbach. "Bond Fatigue of TRC with Epoxy Impregnated Carbon Textiles." Applied Sciences 9, no. 10 (2019): 1980. http://dx.doi.org/10.3390/app9101980.
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For the economical construction of fatigue loaded structures with textile reinforced concrete (TRC), it is necessary to investigate the fatigue behavior of the materials. Since next to the tensile load-bearing behavior, the bond behavior of a material is crucial as well, the present paper deals with the bond fatigue of TRC with epoxy-impregnated carbon textiles. First, static tests are carried out to determine the sufficient anchorage length of the investigated material combination. Afterwards, the influence of cyclic loading on the necessary anchorage length, deformation, stiffness, and residual strength is investigated. The results of the cyclic tests are summarized in stress-number of cycles to failure (S-N) diagrams. In the end, it can be said that the cyclic loading has no negative impact on the necessary anchorage length. If specimens withstand the cyclic loading, there is no difference between their residual strength and the reference strength. The failure of specimens occurs only at high load levels, provided that the anchorage length is sufficient.
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Ghoddousi, P., R. Ahmadi, and M. Sharifi. "Fiber pullout model for aligned hooked-end steel fiber." Canadian Journal of Civil Engineering 37, no. 9 (2010): 1179–88. http://dx.doi.org/10.1139/l10-053.
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The main objective of this study is to derive an analytical model for the pullout behavior of hooked-end steel fiber. The pullout behavior of hooked-end steel fiber comprises a component due to interfacial bond stress at the fiber–matrix interface and a component due to mechanical anchorage at the hook end of the fiber. To study the first component, the effects of hooks on the distributions of the force and stresses along the fiber length are analyzed. Then these results are used, with the concept of bond shear stress versus slip relation between fiber and matrix, to obtain a force component due to the interfacial bond. After that the required theoretical relations are obtained to determine the component due to the mechanical anchorages. Finally, the model is validated with two existing experimental results on the hooked-end steel fiber pullout. The results show that the proposed model is able to estimate the pullout behavior of hooked-end steel fiber.
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Su, Qing Tian, and Dong Fang Wang. "Mechanical Analysis for Anchorage Zone Connecting Main Cable and Main Girger of Self-Anchored Suspension Bridge." Applied Mechanics and Materials 178-181 (May 2012): 2281–84. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.2281.
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Self-anchored suspension bridge is a self-balancing system by anchored the main cable at each end of main girder. With complicated configuration and important rule of transferring tension in main cable to main girder, the anchorage region is one of the most critical issues during designing a self-anchored suspension bridge. It is impossible to fully understand the mechanical behavior only by spatial beam and column model but spatial refined model. Because the behavior of anchorage region is greatly influenced by its boundary condition, in this paper, reasonable length of main girder in calculation model is discussed based on the spatial refined model. The mechanical behavior of initial anchorage structure is calculated. A modified anchorage configuration is proposed according to the stresses distribution of anchorage zone. Calculation results show the modified anchorage configuration can make the force transferring smoothly and decrease the stresses of anchorage structure, and it can be referenced to similar bridges.
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Zhuang, Ning, Honghan Dong, Da Chen, and Yeming Ma. "Experimental Study of Aged and Seriously Damaged RC Beams Strengthened Using CFRP Composites." Advances in Materials Science and Engineering 2018 (October 21, 2018): 1–9. http://dx.doi.org/10.1155/2018/6260724.
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This paper presents results from experiments on aged and seriously damaged reinforced concrete (RC) beams strengthened with different arrangements of external carbon fiber-reinforced polymer (CFRP) laminates and end anchorages. Seven RC beams from an old bridge, measuring 250 × 200 × 2300 mm, were tested. All specimens were loaded to yield load to evaluate initial mechanical properties. Then, these seriously damaged specimens were repaired using different CFRP-reinforcing schemes and reloaded to failure. The yield load growth due to CFRP reinforcement ranged from 5% to 36%. Different parameters including CFRP dimension and position, bonding length, and end anchorage were investigated and facilitated conclusions on beam ductility, load-midspan deflection response, and failure mode. This research contributes to knowledge about the CFRP repair of aged and seriously damaged beams to ensure better performance in overloaded conditions.
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Zhao, Zenghui, Qing Ma, Yunliang Tan, and Xiaojie Gao. "Load transfer mechanism and reinforcement effect of segmentally yieldable anchorage in weakly consolidated soft rock." SIMULATION 95, no. 1 (2018): 83–96. http://dx.doi.org/10.1177/0037549718770284.
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Mine disasters, such as large deformation, floor heave, and roof fall, occur extremely easily in weakly consolidated soft rock strata in western China, posing enormous challenges to traditional anchorage support design. To avoid tensile failure of bolts as a result of the superposition effect of stress accumulation, a segmentally yieldable anchorage support, taking into consideration the different failure zones in surrounding rock, is presented in this paper. First, load transfer mechanisms and the process of anchorage failure are analyzed for end anchorage, full-length anchorage, and segmentally yieldable anchorage based on numerical pull-out tests. Results show that the load transfer follows a multipeak chain-like trend in the case of multipoint segmental anchorage, and that the peaks of stress attenuate slowly. Therefore, the proposed anchorage type can leverage the shear strength effectively. Furthermore, numerical models for the applications of the aforementioned three different anchoring modes to weakly consolidated soft strata are established. Results indicate that segmentally yieldable anchorage can withstand larger tensile deformation and surrounding rock deformation. Moreover, the bolt shows higher strength reservation. A combination of these characteristics is conducive to controlling deformation and damage during roadway excavation.
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Nigro, Emidio, Antonio Bilotta, Giuseppe Cefarelli, Gaetano Manfredi, and Edoardo Cosenza. "Bond Models for FRP Bars Anchorage in Concrete Slabs under Fire." Applied Mechanics and Materials 82 (July 2011): 533–38. http://dx.doi.org/10.4028/www.scientific.net/amm.82.533.
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Experimental tests were recently performed to evaluate resistance and deformability of nine concrete slabs reinforced with Fiber Reinforced Polymer (FRP) bars in fire situation by varying (a) external loads in the range of the service loads, (b) concrete cover in the range of usual values (30-50mm), (c) bar end shape (straight or bent) and its length at the end of the concrete members, namely in the zone not directly exposed to fire (250-500mm). Experimental results showed the importance of concrete cover in the zone directly exposed to fire for the protection provided to FRP bars, due to its low thermal conductivity. Moreover, the length of the FRP bars in the zone of slab not directly exposed to fire and its shape at the end of the members was crucial to ensures slab resistance once the resin softening reduced the adhesion at the FRP-concrete interface in the fire exposed zone of slab. In particular the anchorage obtained simply by bending bars at the end of member in a short zone (250mm) allowed attaining a good structural behavior in case of fire equivalent to that showed by slabs characterized by a large anchoring length (500mm). Tests results are briefly compared and discussed in this paper, whereas the behavior of the bar anchorage is carefully examined based on both the results of numerical thermal analysis and the predictions of a bond theoretical model adjusted for fire situation.
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Li, Biao, Yong Xin Yang, Qing Rui Yue, Bin Wang, Peng Yang Zhang, and Hua Wei Cheng. "Experimental Study on Mechanical Properties of CFRP Tendon." Applied Mechanics and Materials 357-360 (August 2013): 1097–101. http://dx.doi.org/10.4028/www.scientific.net/amm.357-360.1097.
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According to GB/T 26743-2011, 37 different surface state of 8 mm CFRP tendons are made on the mechanical properties test to determine some mechanical properties such as tensile strength, elastic modulus and elongation rate. The experiment process, experimental method and failure state are introduced in detail. Considering many factors to the experimental results, the results are analyzed from production process, binder type, anchorage length and fiber species. The results showed that stress-strain curves are straight lines and the failure mechanism has brittle fracture characteristics. From the point of view of detection method, anchor end must adhere sand in accordance with anchorage of resin sleeve in national standard when testing. CFRP tendon of fiber volume ratio 63%-65%, thread depth of which is suggested to be 0.3-0.4mm, is recommended to produce by one molding process. Anchorage length is suggested to be 200mm above.
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Hosen, Md Akter, Mohd Zamin Jumaat, and A. B. M. Saiful Islam. "Inclusion of CFRP-Epoxy Composite for End Anchorage in NSM-Epoxy Strengthened Beams." Advances in Materials Science and Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/812797.
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Nowadays, the use of near surface mounted (NSM) technique strengthening reinforced concrete (RC) structural members is going very popular. The failure modes of NSM strengthened reinforced concrete (RC) beams have been shown to be largely due to premature failure such as concrete cover separation. In this study, CFRP U-wrap end anchorage with CFRP fabrics was used to eliminate the concrete cover separation failure. A total of eight RC rectangular beam specimens of 125 mm width, 250 mm depth, and 2300 mm length were tested. One specimen was kept unstrengthened as a reference; three specimens were strengthened with NSM steel bars and the remaining four specimens were strengthened with NSM steel bars together with the U-wrap end anchorage. The experimental results showed that wrapped strengthened beams had higher flexural strength and superior ductility performance. The results also show that these beams had less deflection, strain, crack width, and spacing.
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Islam, Md Mashfiqul, Ashfia Siddique, Alireza Pourhassan, Md Arman Chowdhury, and Jarin Tasnim. "Flexural Capacity Enhancement of Timber Beams Partially Confining the Principal Compression Arch using Carbon Fiber Reinforced Polymer Composites." Transportation Research Record: Journal of the Transportation Research Board 2673, no. 11 (2019): 276–85. http://dx.doi.org/10.1177/0361198119851051.
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Timber is widely used as a structural element because of its engineering and mechanical properties. This study focuses on the flexural behavior of timber beams externally reinforced with carbon fiber reinforced polymer (CFRP) composites at the tension face and the responses of the fundamental principal compression arch because of confinement from end anchorage. Beams of three different types of timber are studied. All the beams had the same length, width, and span length and were tested under four-point loading. Different CFRP lamination techniques were adopted, with and without U-clamp confinement as end anchorage, to investigate the flexural capacity enhancement of CFRP strips as reinforcement for timber beams. The profile of the principal compression arch is estimated experimentally from fundamental flexural strain-along-depth phenomena by post-processing high definition images extracted from test videos employing digital image correlation technique (DICT) in the MATLAB R2011a framework. Similar responses were found from finite element analysis using ANSYS 11.0. Effective confinement of the principal compression arch produced significant enhancements of flexural capacities and stiffness in the strengthened timber beams.
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Hsu, Shih Tsung. "A Numerical Study on the Uplift Behavior of Under-Reamed Anchors in Silty Sand." Advanced Materials Research 189-193 (February 2011): 2013–18. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.2013.
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Ground anchors are common to be employed in geotechnical engineering. Under a limited space of an urban district or a restricted thick of an anchored stratum, an under-reamed anchor could meet both the requirements of a short length and a high anchorage capacity. To investigate the anchorage mechanism of the anchor, a series of triaxial tests was performed to obtain the parameters demanded for a constitutive model, SHASOVOD (A continuous strain hardening/ softening and volume dilatancy model for cohesionless soil during stressing). A numerical program was then developed to study the uplift behavior of the under-reamed anchor in silty sand. Analyzing results show that, for two under-reamed anchors located in different test sites, the complete load-displacement curves estimated numerically were consisted with those measured from the field test. The total load, friction load and end bearing do not reach their peaks simultaneously. According to the behavior of the end bearing, a critical overburden depth H of 6D was found to classify an under-reamed anchor as a shallow anchor or a deep anchor.
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Mongiardini, Mario, Ronald K. Faller, John D. Reid, and Dean L. Sicking. "Dynamic Evaluation and Implementation Guidelines for a Nonproprietary W-Beam Guardrail Trailing-End Terminal." Transportation Research Record: Journal of the Transportation Research Board 2377, no. 1 (2013): 61–73. http://dx.doi.org/10.3141/2377-07.
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Most state departments of transportation use simple adaptations of crashworthy guardrail end terminals, which typically include breakaway posts and an anchor cable, for downstream anchorage systems. The guardrail safety performance for vehicular impacts occurring in close proximity to these simplified, downstream anchorage systems is not well known. Further, the length of need (LON) for the downstream end of these systems has yet to be adequately determined. This research project assessed the safety performance of the Midwest Guardrail System (MGS) for impacts occurring in close proximity to a nonproprietary, trailing-end guardrail terminal under the Test Level 3 conditions of the Manual for Assessing Safety Hardware. The two research objectives were to (a) determine the end of the LON for impacts with light pickup trucks and (b) investigate potential risks for a small passenger car to become unstable when striking the downstream end of the MGS anchored by the nonproprietary, trailing-end terminal. Numerical simulations were carried out to identify the most critical impact location for the 1100C small car and the end of the LON for the 2270P pickup truck. In full-scale crash tests, considerable snag of the 1100C vehicle occurred; however, occupant risk values and vehicle stability were within acceptable limits. The crash test with the 2270P pickup indicated that the end of the LON was located at the sixth post from the downstream-end post. Guidelines were proposed for installing the MGS to shield hazards in close proximity to the tested nonproprietary, trailing-end terminal.
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Hu, Wen Chi, and Shih Tsung Hsu. "Numerical Modeling of Earth Structures: Frictional Anchors in Sand." Advanced Materials Research 486 (March 2012): 214–20. http://dx.doi.org/10.4028/www.scientific.net/amr.486.214.
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This research performed a series of triaxial tests on sandy specimens to obtain the parameters needed for a constitutive model. The model is capable to simulate the strain hardening/softening and the volumetric dilation of sandy soil during stressing. The model and the related parameters were then employed in the commercial software FLAC2D to analyze the uplift behavior of various frictional anchors in sandy soil. Analysis results indicate that the friction stress along the fixed end of the anchor with a long fixed length exhibits progressive yielding under not only for a tension but also for a compression anchor. The progressive yielding behavior could be eliminated using a compound anchor because of the upward and downward transfer of load within the anchor shaft from the anchorage body. Therefore, a compound anchor can generate a higher anchorage capacity of all frictional anchors.
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Peterman, Robert J., Julio A. Ramirez, and Jan Olek. "Design of Semilightweight Bridge Girders: Development-Length Considerations." Transportation Research Record: Journal of the Transportation Research Board 1696, no. 1 (2000): 41–47. http://dx.doi.org/10.3141/1696-06.
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In a recent study, 25 development-length tests were conducted on rectangular and T-shaped semilightweight beams having design compressive strengths of 48 MPa (7,000 psi) and 69 MPa (10,000 psi). In the rectangular beam tests, the design moment capacity was exceeded in every case. However, in the tests on T-shaped beams, bond failure occurred in some specimens immediately after the formation of a flexure-shear crack. Additional tests were then conducted on similar T-shaped beams having varying amounts of transverse reinforcement near the point load. These tests showed that bond failure could be prevented by increasing the transverse reinforcement near the point of maximum moment. The study showed that the shift in the tension force that occurs when flexural cracks turn diagonally may lead to bond failure if sufficient anchorage of the strand is not provided. Therefore, the investigators recommend that the current AASHTO requirements for strand development be enforced at a “critical section” located at a distance dp from the point of maximum moment toward the free end of the strand, where dp is the distance from the extreme compression fiber to the centroid of the prestressed reinforcement.
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Yang, Keun-Hyeok, and Ju-Hyun Mun. "Cyclic Flexural and Shear Performances of Beam Elements with Longitudinal Glass Fiber Reinforced Polymer (GFRP) Bars in Exterior Beam-Column Connections." Applied Sciences 8, no. 12 (2018): 2353. http://dx.doi.org/10.3390/app8122353.
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The objective of this study is to examine the effect of the poor anchorage length of glass fiber reinforced polymer (GFRP) bars used for longitudinal reinforcement on the flexural and shear performances of beam elements in exterior beam–column connections made using high-strength materials. Six exterior beam–column connection specimens were tested under reversal cyclic loads applied at the free-end of the beam. The selected strength categories of materials in the beam element were as follows: 35 MPa and 70 MPa for the design compressive strength of concrete, 400 MPa and 600 MPa for the yield strength of conventional longitudinal steel bars, and 800 MPa for the tensile strength of the GFRP bar. All the longitudinal steel bars of the beams satisfied the minimum requirements of the provisions of ACI 318–14, whereas all the longitudinal GFRP bars of the beam were linearly anchored into the column section, resulting in poor anchorage length, especially for the beam with the concrete compressive strength of 35 MPa. The flexure-governed beams with GFRP bars exhibited a greater increasing rate in displacement at the pre-peak state and did not display the plastic flow characteristic after the peak load when compared with companion beams with steel bars. The beams with GFRP bars possessed lower diagonal cracking strengths and shear capacities than the companion beams with steel bars although the shear capacities of the beams with GFRP bars could be conservatively predicted using the design equation of ACI 440.1R–15 provision. The low elastic modulus and elongation capacity of GFRP bars resulted in large displacements and brittle post-peak beam performances. Furthermore, the lack of anchorage length of GFRP bars in exterior beam–column connection significantly reduced the flexural strength and ductility of the beam element.
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Sun, Wen Bin, Wei Zhong He, and Yang Jiang. "Bond Strength on the Interface between Concrete and Steel and Development Length of Reinforcing Bars in RC Structures." Applied Mechanics and Materials 94-96 (September 2011): 456–59. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.456.
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For the analysis and design of RC structures, there is a fundamental assumption that the strain in an embedded reinforcing bar is the same as that in the surrounding concrete. Therefore, bond forces must be developed on the interface between concrete and steel, such as to prevent significant slip from occurring at the interface. An end anchorage may be considered reliable if the bar is embedded in to concrete a prescribed distance known as the development length of the bar. If in the beam the actual extended length of a bar is equal to or greater than this required development length, no premature bond failure will occur. Research has indicated that the development length was influenced by tensile strength of concrete, surface and diameter of bar, cover distance, bar spacing, transverse reinforcement, and other factors. Current design methods in different countries’ Codes, attentions are directed toward providing adequate length of embedment, which will ensure development of the full strength of the bar.
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Al-Tamimi, Adil K., Rami Hawileh, Jamal Abdalla, and Hayder A. Rasheed. "Effects of Ratio of CFRP Plate Length to Shear Span and End Anchorage on Flexural Behavior of SCC RC Beams." Journal of Composites for Construction 15, no. 6 (2011): 908–19. http://dx.doi.org/10.1061/(asce)cc.1943-5614.0000221.
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Jokūbaitis, Aidas, Juozas Valivonis, and Adomas Zubrus. "THE INFLUENCE OF PRESTRESS LOSSES ON THE ANCHORAGE ZONE OF PRESTRESSED CONCRETE MEMBER / ĮTEMPTŲJŲ GELŽBETONINIŲ ELEMENTŲ ĮTEMPIŲ NUOSTOLIŲ ĮTAKA INKARAVIMO ZONAI." Engineering Structures and Technologies 6, no. 1 (2014): 25–32. http://dx.doi.org/10.3846/2029882x.2014.957902.
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Article briefly discusses the factors affecting bond between concrete and reinforcement of prestressed concrete member. Behavior of prestressed concrete member during release of reinforcement is discussed. Comparative analysis of equations, which describes relation between strand draw-in and transfer length, is presented. Article analyses distribution of loss of prestress at the anchorage zone of prestressed concrete member. Estimation of rational position of strands at the anchorage zone of flexural prestressed concrete member was performed. Influence of constant and linearly variable stress distribution at the end of the strand and member cross-section hight on the position of the reinforcement at the member crosssection is analysed. Straipsnyje trumpai aptariami įtemptųjų gelžbetoninių konstrukcijų sukibimą tarp betono ir armatūros lemiantys veiksniai. Aprašoma įtemptojo gelžbetoninio elemento elgsena atleidžiant armatūrą. Pateikiama kitų autorių eksperimentiniais tyrimais nustatytų priklausomybių tarp lynų praslydimo ir įtempių perdavimo ilgio lyginamoji analizė. Straipsnyje analizuojamas įtempių nuostolių pasiskirstymas įtemptojo gelžbetoninio elemento inkaravimo zonoje, apskaičiuota racionali įtemptojo lenkiamojo gelžbetoninio elemento lynų padėtis inkaravimo zonoje. Analizuojama, kokią įtaką lynų padėčiai elemento skerspjūvyje daro nuolatinis ir kintamas įtempių pasiskirstymas lynų galuose bei elemento skerspjūvio aukštis.
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Feng, Xiaowei, Nong Zhang, Guichen Li, and Gangye Guo. "Pullout Test on Fully Grouted Bolt Sheathed by Different Length of Segmented Steel Tubes." Shock and Vibration 2017 (2017): 1–16. http://dx.doi.org/10.1155/2017/4304190.
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In order to evaluate the anchorage performance of rebar bolt sheathed by different length of segmented steel tubes, a total of eight groups of pullout tests were conducted in this study. The steel tubes, segmented by 5 cm, 7 cm, 9 cm, 10 cm, and 15 cm, utilized in current study were bonded together by a high performance two-component adhesive to form standard 30 cm long steel tube. Unlike axial stress distribution in bolt, the axial stress distribution in steel tube showed exponential decrease trend from tube-clamp end to bolt-clamp end; thus a series of interesting results were observed. For instance, the sequence for segments detachment had its specific order of priority; the failure form of bolting system, the load oscillation characteristics, and the final displacement were highly determined by the length of the last segment, namely, the one fixed by clamp of testing machine. Moreover, the load-displacement relationship for some particular samples was further investigated from the perspective of energy transformation, and the disequilibrium extension of interfacial decoupling was also discussed. This paper, from a relatively idealized perspective, presents a laboratorial solution to interpret the mechanical performance of the bolt installed in layered strata; so far at least it demonstrates that a bolt installed in comparatively thicker layer of strata can last more durable and stable.
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Jiang, Shi Yong, Yong Ye, and Wei Fei. "Experiment on the Bonding Performance of BFRP Bars Reinforced Concrete." Applied Mechanics and Materials 174-177 (May 2012): 993–98. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.993.
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Through the pull-out test methods, the concrete strength、reinforcement diameter Basalt Fiber Reinforced Plastics Bars、the anchorage length、 stirrup rate and other factors on the bonding properties of the BFRP reinforced concrete is analyzed. The BFRP bars and reinforcing steel bars bonding properties is compared. BFRP reinforced concrete bond failure mode has two types .As the concrete strength increases, the bond strength of the BFRP reinforced concrete increased. With the increase BFRP bars diameter and shear lag relationship, the cohesive force of the BFRP reinforced concrete decrease accordingly. And the failure modes of the shape of the BFRP reinforcement concrete in BFRP bonding properties with a big impact for the specimens’ configuration stirrups on the ductility. When BFRP bars loading under the same load level, the end of the slip is greater than the free end slip.
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Čítek, David, Jan L. Vítek, Jiří Kolísko, Petr Huňka, and Stanislav Řeháček. "Assessment of Bond Behavior of UHPC and Prestressing Strands." Advanced Materials Research 1000 (August 2014): 247–50. http://dx.doi.org/10.4028/www.scientific.net/amr.1000.247.
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Ultra High Performance Concrete - UHPC is a relatively new type of composite material with outstanding features (high compressive strength, high tensile strength and high durability). Also the bond strength between steel reinforcement and UHPC is better than that in ordinary concrete. This fact needs to be quantified, because no standard prescribes the bond behavior of UHPC and design of UHPC in general. The main aim of the experimental research was to determine the average bond stress between prestressing strands and different types of UHPC. The second aim was to show very significant increase of the average shear stress in bond of UHPC compared to that of ordinary concrete. In order to determine the bond capacity, two types of experimental specimens – parts of prestressed girders and specimens prepared according to standard, were tested in the laboratory. The specimens were prepared for pull out test, in which the prestressing strand is pulled out from the cube or part of girder made from UHPC. The tensile force in strand and slip of the end of reinforcement were measured and then the average bond stress was examined. The influence of different material properties and different anchorage lengths of prestressing strands to bond behavior of UHPC was examined and results were compared to these phenomena of ordinary concrete. The results of bond test led to the conclusion that the application of UHPC can significantly reduce the anchorage length of reinforcement compared with that in ordinary concrete.
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Nishiyama, M., H. Mugurama, and F. Watanabe. "Hysteretic restoring force characteristics of unbounded prestressed concrete framed structure under earthquake load." Bulletin of the New Zealand Society for Earthquake Engineering 22, no. 2 (1989): 112–21. http://dx.doi.org/10.5459/bnzsee.22.2.112-121.
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An analytical method, by which hysteretic restoring force characteristics of unbonded prestressed concrete framed structure can be statically pursued on the basis of material properties, is presented. The bond-slip relationship between concrete and prestressing tendon is taken into account, and thus the method covers unbonded members and bonded members. For verifying the propriety of the analytical method, the experiment is carried out on a portal frame with an unbonded prestressed concrete beam of 4.2 m in length and reinforced concrete columns of 1 m in height. High intensity reversed cyclic lateral loading is applied. The experimental results show a good agreement with the analytical ones in terms of load-deflection relation and the fluctuation of the tendon stress at anchorage end.
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Aguilar-Pérez, Luis Antonio, José Israel Sánchez-Cruz, Juan Alejandro Flores-Campos, and Christopher René Torres-SanMiguel. "Numerical and Experimental Assessment of a Novel Anchored for Intramedullary Telescopic Nails Used in Osteogenesis Imperfecta Fractures." Applied Sciences 11, no. 12 (2021): 5422. http://dx.doi.org/10.3390/app11125422.
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Osteogenesis Imperfecta (IO) is a bone disease mainly characterized by the low bone density that produces common fractures in children around 0–7 years. The use of metal implants is a typical treatment of this disease. The intramedullary telescopic nail (ITN) was inspired by the progressive growth in the long bones such as the femur or humerus during children’s aging. This work shows an experimental assessment of the ITN’s, focusing on their fixation; the proposed improvements in the design of the intramedullary nail studied include the separation of the element into two parts for telescopic enlargement, minimal invasive fixation through the distal anchorage, and the double auto-drilled end for fixation on the distal and proximal section of the bone. The samples were manufactured in 316 L steel and mounted on specialized jaws to replicate the implants’ boundary conditions. The experimental test was repeated three times to report the intramedullary telescopic nail’s behavior at three lengths. The results show that the device supports only 79.06 N when not at extension length. However, if the device is extended 150% it will support 46.87 N which suggests that intramedullary telescopic nails can only increase by 25% of their original length before they fail.
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Schanack, Frank, Galo Valdebenito, and Jorge Alvial. "Seismic Damage to Bridges during the 27 February 2010 Magnitude 8.8 Chile Earthquake." Earthquake Spectra 28, no. 1 (2012): 301–15. http://dx.doi.org/10.1193/1.3672424.
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The 27 February 2010 Chile earthquake is currently the fifth-strongest earthquake measured in the world. Despite this fact, the damage to the road infrastructure can be classified as moderate. Of the 6,000 state bridges in the affected region, only about 30 bridges had to be closed to traffic. This paper includes the most pertinent results of a field investigation of the seismic damage to 100 bridges. The majority of the bridges exhibited only minor damage such as concrete spalling, expansion joint damage, and settlement of the embankment. However, severe damage was reported in 19 bridges, including web rupture due to a missing end diaphragm, a span collapse due to insufficient anchorage and missing stoppers, a span collapse due to a small seat length, and cracking at the welding notch in the steel girders. The most important lessons learned are described and recommendations for future bridge designs are given.
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Arevalo Gomez, Roger. "Measurement and analysis of vibrations - evaluation of the criteria of acceptance ISO Standard 10816-6." Ciencia y tecnología de buques 13, no. 26 (2020): 39–44. http://dx.doi.org/10.25043/19098642.196.
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During the reception and / or delivery tests of a ship, vibration measurement and analysis is made to the propulsion line in order to evaluate and predict the condition of the machinery. The values taken during the measurement of the vibrations are evaluated with the acceptance criteria provided by the standards. International Standard ISO 10816-6 (1995) focuses on reciprocating machinery with power of greater than 100kW, is used by both analysts and manufacturers of propulsion machinery for ships. Through this work, we intend to evaluate the acceptance criteria of this norm in boats smaller than 100 meters. At the end of this work it is concluded that the standard must be updated, indicating and differentiating the acceptance criteria for machinery taking into account its type of anchorage to the structure (flexible or rigid), boats with length less than or greater than 100 meters and the Ship building material (Aluminum, Steel or Composite material).
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Salles, L. S., and J. T. Balbo. "Experimental continuously reinforced concrete pavement parameterization using nondestructive methods." Revista IBRACON de Estruturas e Materiais 9, no. 2 (2016): 263–74. http://dx.doi.org/10.1590/s1983-41952016000200007.
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ABSTRACT Four continuously reinforced concrete pavement (CRCP) sections were built at the University of São Paulo campus in order to analyze the pavement performance in a tropical environment. The sections short length coupled with particular project aspects made the experimental CRCP cracking be different from the traditional CRCP one. After three years of construction, a series of nondestructive testing were performed - Falling Weight Deflectometer (FWD) loadings - to verify and to parameterize the pavement structural condition based on two main properties: the elasticity modulus of concrete (E) and the modulus of subgrade reaction (k). These properties estimation was obtained through the matching process between real and EverFE simulated basins with the load at the slab center, between two consecutive cracks. The backcalculation results show that the lack of anchorage at the sections end decreases the E and k values and that the longitudinal reinforcement percentage provides additional stiffness to the pavement. Additionally, FWD loadings tangential to the cracks allowed the load transfer efficiency (LTE) estimation determination across cracks. The LTE resulted in values above 90 % for all cracks.
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Mutinelli, Sabrina, and Mauro Cozzani. "Rapid maxillary expansion in contemporary orthodontic literature." APOS Trends in Orthodontics 6 (May 30, 2016): 129–36. http://dx.doi.org/10.4103/2321-1407.183148.
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We have reviewed our retrospective research about rapid maxillary expansion performed in the early mixed dentition to summarize the results of different studies regarding maxillary dental arch width variation and crowding improvement in light of contemporary literature. The aim is to define the effects of treatments followed until the end of dental arch growth. In all studies, a Haas expander anchored to the deciduous dentition was used. The samples consisted of treated patients with and without a lateral crossbite and homogeneous untreated individuals as controls. Two additional control groups of adolescents and adults in dental Class 1 were also compared. As a result of the analysis, rapid maxillary expansion with anchorage to the deciduous dentition was found to be effective in increasing transverse width in intermolar and intercanine areas, and the change was preserved until the full permanent dentition stage. When performed before maxillary lateral incisors have fully erupted, this procedure allows for a rapid increase in the arch length in the anterior area and consequently, in the space available for permanent incisors with a stable reduction in crowding over time.
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Zhang, Ming-yi, Zheng Kuang, Xiao-yu Bai, and Xiao-yu Chen. "Pullout Behavior of GFRP Anti-Floating Anchor Based on the FBG Sensor Technology." Mathematical Problems in Engineering 2018 (December 27, 2018): 1–10. http://dx.doi.org/10.1155/2018/6424791.
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Building anti-floating anchors have been increasingly used in recent years, but conventional steel anchors under service conditions are easily subjected to chemical erosion. Glass fiber reinforcement polymer (GFRP) is a promising solution to this problem. In this study, field pullout tests were conducted on three full instrumented GFRP anti-floating anchors in weathered granite. Specifically, the GFRP anchors during pultrusion were innovatively embedded with bare fiber Bragg grating (FBG) sensors to monitor the axial force distribution along depth. It was found that the embedded FBG could reliably monitor the axial force distribution of GFRP anchors. The ultimate pullout force of a GFRP anchor with diameter of 28 mm and anchorage length of 5 m was up to 400 kN. The GFRP anchor yielded at 0.8 m underground. Force distribution and field photos at failure indicated shear failure occurred at the anchor/bolt interface at the end of the tests. The feasibility of the GFRP anti-floating anchor was also verified in civil engineering. Finally, an elastic mechanical model and Mindlin’s displacement solution are used to get distribution functions of axial force and shear stress along the depth, and the results accord with the test results.
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Chen, Zongping, Jiyu Tang, Xingyu Zhou, Ji Zhou, and Jianjia Chen. "Interfacial Bond Behavior of High Strength Concrete Filled Steel Tube after Exposure to Elevated Temperatures and Cooled by Fire Hydrant." Materials 13, no. 1 (2019): 150. http://dx.doi.org/10.3390/ma13010150.
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For the engineering structure in case of fire, a fire hydrant is generally used for extinguishing the fire. This paper presents an experimental investigation on interfacial bond behavior of high-strength concrete-filled steel tube (HSCFST) after exposure to elevated temperatures and cooled by fire hydrant using the pull-out test of 22 specimens. According to the experimental study, the failure mechanism of HSCFST exposed to elevated temperatures and water-cooling (ETWC) was revealed, the influence of various parameters on the bond behavior was analyzed, and the calculation formula of the bond strength of HSCFST subjected to ETWC was put forward. The results show that the load-slip curves of the loading end and the free end of the specimen are basically similar, and can be divided into three types of typical curves. In the push out test, the strain on the outer surface of the steel tube is exponentially distributed with its distance from the loading end. After ETWC exposure, the bond strength of the specimen is less affected by the concrete strength, which is inversely proportional to the anchorage length, and it is basically stable after the constant temperature duration is longer than 60 min. With the increase of the maximum temperature, the ultimate bond strength increases first, then decreases and then increases, and the residual bond strength increases first and then decreases. Besides, the study indicate that cooling method has significant influence on the bond behavior, compared with natural cooling specimens, the ultimate bond strength, residual bond strength, and shear bond stiffness of water-cooling specimens are smaller, and the interfacial energy dissipation capacity is larger.
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Sicking, Dean L., John R. Rohde, and John D. Reid. "Design and Development of Steel Breakaway Posts." Transportation Research Record: Journal of the Transportation Research Board 1720, no. 1 (2000): 59–66. http://dx.doi.org/10.3141/1720-07.
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The current generation of NCHRP Report 350-compliant guardrail terminals all use wooden breakaway posts in the terminal section. The first two end posts are typically breakaway cable terminal posts inserted into steel foundation tubes that are joined with a ground strut to provide the anchorage capacity. Wood is readily available and inexpensive, but it also has many drawbacks. The quality of the wood and the associated breaking forces vary widely. The strength of a wooden post is affected by many factors, including post size, ring density, knot location and size, cracks and checks, species, and moisture content. Results are presented of an effort to design and develop steel breakaway posts for guardrail terminals. The breakaway steel post system described has been successfully tested for use in a tangent terminal. The post exhibited consistent strength for redirection impacts and failed at very low loads during head-on impacts. The breakaway steel post actually improved the redirective performance of the SKT-350 during a 2020-kg (4,450-lb) pickup truck impact at the beginning of the length of need. These breakaway steel posts have been shown to meet NCHRP Report 350 performance criteria and should provide highway agencies with an alternative where wood posts are unacceptable.
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Köroğlu, Mehmet Alpaslan. "Artificial neural network for predicting the flexural bond strength of FRP bars in concrete." Science and Engineering of Composite Materials 26, no. 1 (2019): 12–29. http://dx.doi.org/10.1515/secm-2017-0155.
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AbstractThe bond strength between fibre-reinforced polymer (FRP) rebars and concrete is one of the most significant aspects of composite behaviour for rebars and concrete. In this study, a database of 408 beam type specimens consisting of beam end specimens, beam anchorage specimens and splice beam specimens was compiled from the current literature and used to develop a simple prediction using the artificial neural network (ANN). The data used for modelling were organised in a format of eight input parameters that include FRP type, cover bar surface, confinement, bar diameter (db), concrete compressive strength $(\sqrt {{f_c}} )$, minimum cover-to-bar-diameter ratio (c/db), bar-development-length-to-bar-diameter ratio (l/db), and the ratio of the area of transverse reinforcement to the product of transverse reinforcement spacing, the number of developed bars and bar diameters (Atr/sndb). Additionally, a simple prediction formula by regression analysis was developed. The root mean square error and R2 values of the testing data were found in order to compare the results of both ANN and the proposed model with existing regulations. The new ANN model predicts the bond strength of FRP bars in reinforced concrete with 0.8989 R2, thus yielding better results when compared with existing regulations.
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Ali, MS Mohamed. "Analytical models to predict structural behaviour of reinforced concrete beams bonded with prestressed fibre-reinforced polymer laminates." Advances in Structural Engineering 21, no. 4 (2017): 532–44. http://dx.doi.org/10.1177/1369433217732666.
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The strengthening of reinforced concrete members with prestressed fibre-reinforced polymer laminates has been investigated by researchers due to major improvements in member serviceability characteristics. Currently, analytical models generally employ mostly empirical procedures in predicting member behaviour, and as a result, the analytical results exhibit poor correlation to experimental investigations. In this article, an analytical model is developed using new and existing theoretical techniques to critically analyse strengthened reinforced concrete beams for a range of loading scenarios to generate moment–rotation and load–deflection relationships. The prestress level and the intermediate crack debonding strain of the prestressed fibre-reinforced polymer laminate with the inclusion of mechanical end anchorage were highlighted as key parameters within the model. The proposed model adopts closed-form solutions to allow for a wide range of beams with varying steel and fibre-reinforced polymer reinforcement ratios and dimensions. The model incorporates calibrated crack spacing theory to predict the crack width and spacing as well as the length of the cracked region in the beam. The models have good correlation with collected experimental data and thus can be used for the analysis of reinforced concrete beams strengthened with prestressed fibre-reinforced polymer, throughout all stages of loading from serviceability to failure.
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Wang, Peng, Nong Zhang, Jiaguang Kan, Zhengzheng Xie, Qun Wei, and Wenhao Yao. "Fiber Bragg Grating Monitoring of Full-bolt Axial Force of the Bolt in the Deep Strong Mining Roadway." Sensors 20, no. 15 (2020): 4242. http://dx.doi.org/10.3390/s20154242.
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With the increase of mining depth and strength, the evolution of bolt axial force is increasingly becoming important for ensuring the reliability and safety of support. To improve the problem of the existing coal mine roadway pressure-monitoring method, whereby it is difficult to continuously monitor the axial force of the bolt over a long period of time, a full rod fiber bragg grating (FBG) force-measuring bolt and system were designed based on the principle of fiber grating sensing. It was found that a trapezoidal groove is a relatively better groove. The linearity between the center wavelength offset of the fiber grating and the axial force was more than 0.99, and the conversion formula between the axial force of the bolt rod and the wavelength change of the fiber grating were obtained. The real-time monitoring revealed that the axial force of the bolt obviously changed before and after compression. The axial force distribution curve can be divided into the stable zone, growth zone, and peak zone. The influence of the roadway abutment pressure was approximately 130 m ahead of the working face, and the peak area was within the 25–35 m range of the advance working face. The axial force of the bolt rod at the end of the anchorage linearly increased with the tail end of the bolt, the axial force of the free segment was the largest, and the overall stress was essentially the same. The application results demonstrate the feasibility and effectiveness of the FBG full-length force bolt.
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Zhang, Zhiqiang, Yin Liu, Junyang Teng, Heng Zhang, and Xin Chen. "An Investigation into Bolt Anchoring Performance during Tunnel Construction in Bedded Rock Mass." Applied Sciences 10, no. 7 (2020): 2329. http://dx.doi.org/10.3390/app10072329.
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The anchor bolt is a key point of tunnel design in bedded rock mass. The previous theory of anchorage support falls does not fulfil engineering requirements, and the stability of bedded rock must be addressed by empirical methods. To investigate the bolt anchoring performance for bedded rock mass under different anchoring methods, the rock failure mode under shear and tensile stresses in bedded rock was examined in this paper. The results showed that bolt anchoring for rock is achieved mainly through the bonded restoration of surrounding rock near the drill holes by means of an anchoring agent and the supporting resistance provided by the bolt body. It was observed that the strength parameters of bedded rock were increased under the anchoring effect. Full anchoring bolts were especially effective. In addition, it was observed that, in the absence of bolts, the failure form changed from shear to split. In the case of bolting, the failure plane occurred parallel to the bolt’s axis. The shearing began along the interface between the hard and soft rock bedding. Compared to end bolt anchoring, full-length bolt anchoring was more capable of offering an anchoring effect. The latter offered a greater increase in the strength and greater shear-bearing capacity of the rock, which ultimately enabled the rock to bear more load.
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Panizza, Matteo, Enrico Garbin, Maria Rosa Valluzzi, and Claudio Modena. "Experimental Study of the Bond of FRP Applied to Natural Stones and Masonry Prisms." Key Engineering Materials 624 (September 2014): 453–60. http://dx.doi.org/10.4028/www.scientific.net/kem.624.453.
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Compared to more traditional techniques, the application of Externally Bonded-Fibre Reinforced Polymers (EB-FRP) represents a viable alternative for the strengthening of masonry structures, also in case of Cultural Heritage buildings where strict requirements need to be met, aimed at minimizing the impact of the intervention. Since the FRP-to-masonry bond behaviour strongly affects design and effectiveness of such interventions, several investigations have been carried out in recent years to study this phenomenon, generally based on the longer experience developed for concrete substrates. Mortar joints, which are geometrical and mechanical discontinuities, distinguish and characterize masonry substrates from concrete ones, and therefore deserve a special attention as far as their role in the bond behaviour is not clarified yet. This paper, aimed at giving a contribution also from a methodological point of view, presents the main experimental results of shear tests carried out on glass composites (GFRP) applied to natural calcareous stones (pietra leccese), to lime mortar blocks and to masonry prisms made by coupling stones and lime mortar. Overall 22 shear tests were performed, keeping a bonded length of 200 mm for stones and mortar specimens while it was changed from 65 mm (corresponding to one stone and one mortar joint) to 195 mm (three stones and three mortar joints) in the case of masonry prisms. The effect of the FRP end anchorage on the test development was investigated as well, and results of the experimental tests are herein discussed in detail.
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Iraqi, Driss, Isabelle Duchesne, and Jacques-André Rioux. "Growth and Potential of Root Regeneration of Trees Grown in Cupric Hydroxide-coated Fabric." HortScience 30, no. 4 (1995): 794F—794. http://dx.doi.org/10.21273/hortsci.30.4.794f.
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The most widespread deformation observed in container production is root circling. Consequently, root circling often reduces growth, root regeneration, and tree anchorage at transplanting time. The objectives of this study were to test the effectiveness of Cu(OH)2 lined containers on restriction of root tips, tree growth, and potential root regeneration (PRR). Two species were used in this study: Fraxinus pennsylvanica and Acer saccharinum. Species were grown for one season in containers lined with one of six combinations of polymer (P) (0, 30, and 60 g·m–2) and copper (Cu) (0%,0.4%, and 0.8%) -coated fabric. Two other treatments were included as controls: a plastic container and a fabric container. Seedlings of each species were harvest twice: at the first season and after being transplanted from 10- to 75-liter containers. Treatments were randomized in complete blocks with six repetitions. Results of root circling length and dry weight indicate good restriction of root tips for two combinations (30 g of P/m2–0.8% Cu; 60 g of P/m2–0.8% Cu) for all species. However, treatments did not cause any reduction in stem height, trunk diameter, or stem and root dry weight. At the end of the transplanting season, PRR was greater for two combinations (30 g of P/m2–0.8% Cu; 60 g of P/m2–0.8% Cu), especially for green ash. No significant differences were observed between a plastic fabric and the two treatments cited for the other growth parameters. No phytotoxic symptoms were observed throughout the experiment.
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Bunge, R. P., M. B. Bunge, and M. Bates. "Movements of the Schwann cell nucleus implicate progression of the inner (axon-related) Schwann cell process during myelination." Journal of Cell Biology 109, no. 1 (1989): 273–84. http://dx.doi.org/10.1083/jcb.109.1.273.
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Although it has been known for several decades that peripheral myelin is formed from an extended, spiraled, and compacted sheet of Schwann cell (SC) plasma membrane, the mechanism by which this unique spiraling is accomplished remains unknown. We have studied the movements of SC nuclei before, during, and subsequent to myelin formation (over periods of 24-72 h) to determine if this nuclear motion (noted in earlier reports) would provide useful insights into the mechanism of myelinogenesis. We used rodent sensory neuron and SC cultures in which initiation of myelinogenesis is relatively synchronized and bright field conditions that allowed resolution of the axon, compact myelin, and position of the SC nucleus. Observed areas were subsequently examined by electron microscopy (EM); eight myelinating SCs with known nuclear movement history were subjected to detailed EM analysis. We observed that, prefatory to myelination, SCs extended along the length of larger axons, apparently competing with adjacent SCs for axonal surface contact. This lengthening preceded the deposition of compact myelin. SC nuclear circumnavigation of the axon was found to attend early myelin sheath formation. This movement was rarely greater than 0.25 turns per 3 h; on the average, more nuclear motion was seen in relation to internodes that formed during observation (0.8 +/- 0.1 turns/24 h) than in relation to those that had begun to form before observation (0.3 +/- 0.1 turns/24 h). Nuclear circumnavigation generally proceeded in one direction, could be in similar or opposite direction in neighboring myelinating SCs on the same axon, and was not proportional to the number of major dense lines within the myelin sheath. A critical finding was that, in all eight cases examined, the overall direction of nuclear movement was the same as that of the inner end of the spiraling SC process, and thus opposite the direction of the outer end of the spiral. We conclude that the correspondence of the direction of nuclear rotation and inner end of the spiraling cytoplasmic lip implicates active progression of the inner lip over the axonal surface to form the membranous spiral of myelin, the nuclear motion resulting from towing by the advancing adaxonal lip. This interpretation fits with finding basal lamina and macular adhering junctions associated with the external lip of SC cytoplasm; these attributes would imply anchorage rather than movement of this region of the SC.
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Wyka, Tomasz P., Marcin Zadworny, Joanna Mucha, Roma Żytkowiak, Kinga Nowak, and Jacek Oleksyn. "Biomass and nitrogen distribution ratios reveal a reduced root investment in temperate lianas vs. self-supporting plants." Annals of Botany 124, no. 5 (2019): 777–90. http://dx.doi.org/10.1093/aob/mcz061.
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Abstract Background and Aims The reliance on external support by lianas has been hypothesized to imply a reduction in the biomass cost of stem construction and root anchorage, and an increased investment in leaves, relative to self-supporting plants. These evolutionary trade-offs have not been adequately tested in an ontogenetic context and on the whole-plant scale. Moreover, the hypothesis may be extended to other potentially limiting resources, such as nitrogen (N.) Methods Plants belonging to five con-familiar pairs of temperate liana/shrub species were cultivated in 120 L barrels and sequentially harvested over up to three growing seasons. To account for the ontogenetic drift, organ biomass and nitrogen fractions were adjusted for plant biomass and N pool, respectively. Key Results Lianas invested, on average, relatively less biomass in the root fraction in comparison with shrubs. This was offset by only insignificant increases in leaf or stem investment. Even though liana stems and roots showed higher N concentration in comparison with shrubs, plant N distribution was mostly driven by, and largely matched, the pattern of biomass distribution. Lianas also showed a greater relative growth rate than shrubs. The differences between the growth forms became apparent only when ontogenetic drift was controlled for. These results were confirmed regardless of whether reproductive biomass was included in the analysis. Conclusions Our results suggest that temperate lianas, in spite of their diverse, species-specific resource distribution patterns, preferentially allocate resources to above-ground organs at the expense of roots. By identifying this trade-off and demonstrating the lack of a general trend for reduction in stem investment in lianas, we significantly modify the prevailing view of liana allocation strategies and evolutionary advantages. Such a resource distribution pattern, along with the cheap unit leaf area and stem unit length construction, situates lianas as a group close to the fast acquisition/rapid growth end of the life strategy spectrum.
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Warren, Derek T., Qiuping Zhang, Peter L. Weissberg, and Catherine M. Shanahan. "Nesprins: intracellular scaffolds that maintain cell architecture and coordinate cell function?" Expert Reviews in Molecular Medicine 7, no. 11 (2005): 1–15. http://dx.doi.org/10.1017/s1462399405009294.
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Nesprins are a recently discovered family of ubiquitously expressed intracellular proteins. Through alternative transcriptional initiation, termination and splicing, two genes – nesprin-1 and nesprin-2 (also known as syne-1 and syne-2) – give rise to many protein isoforms that vary markedly in size. The largest of these isoforms comprise a C-terminal transmembrane domain (the KLS domain) linked by a spectrin-repeat rod domain to an N-terminal paired, actin-binding, calponin-homology domain. This structure suggests that they are well suited to orchestrate signalling between cell membranes and the cytoskeleton. Other isoforms have variable lengths of this rod domain linked to either end of the protein. Smaller isoforms with the KLS domain are localised at the inner nuclear membrane, where they bind lamin A/C and emerin. Larger nesprin isoforms link the outer nuclear membrane with intracellular organelles and the actin cytoskeleton and are thought to regulate nuclear anchorage and organelle migration. Thus, nesprins might have a variety of fundamental roles in cells, particularly muscle cells where they are highly expressed. We speculate that nesprin mutations might contribute to a broad range of human disease syndromes, including laminopathies.
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Fürst, D. O., M. Osborn, R. Nave, and K. Weber. "The organization of titin filaments in the half-sarcomere revealed by monoclonal antibodies in immunoelectron microscopy: a map of ten nonrepetitive epitopes starting at the Z line extends close to the M line." Journal of Cell Biology 106, no. 5 (1988): 1563–72. http://dx.doi.org/10.1083/jcb.106.5.1563.
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mAbs specific for titin or nebulin were characterized by immunoblotting and fluorescence microscopy. Immunoelectron microscopy on relaxed chicken breast muscle revealed unique transverse striping patterns. Each of the 10 distinct titin antibodies provided a pair of delicate decoration lines per sarcomere. The position of these pairs was centrally symmetric to the M line and was antibody dependent. The results provided a linear epitope map, which starts at the Z line (antibody T20), covers five distinct positions along the I band (T21, T12, T4, T1, T11), the A-I junction (T3), and three distinct positions within the A band (T10, T22, T23). The epitope of T23 locates 0.2 micron before the M line. In immunoblots, the two antibodies decorating at or just before the Z line (T20, T21) specifically recognized the insoluble titin TI component but did not recognize TII, a proteolytic derivative. All other titin antibodies recognized TI and TII. Thus titin molecules appear as polar structures lacking over large regions repetitive epitopes. One physical end seems related to Z line anchorage, while the other may bind close to the M line. Titin epitopes influenced by the contractional state of the sarcomere locate between the N1 line and the A-I junction (T4, T1, T11). We discuss the results in relation to titin molecules having half-sarcomere lengths. The three nebulin antibodies so far characterized again give rise to distinct pairs of stripes. These locate close to the N2 line.
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"Structural Performance of Grouted Sleeve Splice Connectors with Grooves Under Axial Tensile Load for Precast Concrete Structure." International Journal of Engineering and Advanced Technology 9, no. 4 (2020): 564–71. http://dx.doi.org/10.35940/ijeat.d7319.049420.
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This study explains the performance of the proposed grouted sleeve connector with internal Grooves within the sleeve beneath incremental tensile load until failure. In this study, a series of twelve grouted sleeve splice with grooves (GSSG) were tested experimentally beneath incremental tensile load until failure to determine their feasibilities. The connector utilized mild steel pipe as sleeve where the sleeve comprises internal grooves with differing height and width .The mild steel pipe and the grooves are utilized to confine and strengthen the grout and the two dis continued bars joined end-to-end configuration within the sleeve. The specimens are studied and evaluated based on two major aspects; (a) ultimate tensile capacities, whether it is higher than 125% of the specified yield strength, (b) failure modes, The test shows up that, there are two modes of failure which were bar to grout failure and bar broken outside the sleeve. Sex examples out of twelve shows up palatable comes about since it failed due to bar broken outside the sleeve and fulfill palatable ultimate tensile capacity. The stiffness and the ductility of the connectors additionally fulfill. It is found that the grooves on the sleeves are essential to interlock with the confined grout, resisting it from slipping out of the sleeve. The test appears that the performance of the grouted sleeve connector with grooves was represented by grout-bar bond, anchorage length and control action given by the sleeve and the grooves . Possibility consider for tried grouted sleeves detailing their adequacy in agreement with the code arrangements of ACI 318-14 and ECP 203-2018 is displayed. Besides, design equations capturing the parameters influencing the bond strength, the confining pressure, grooves , and the specified embedment length are determined.
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Komini, Chrysoula, Irini Theohari, Andromachi Lambrianidou, Lydia Nakopoulou, and Theoni Trangas. "PAPOLA contributes to cyclin D1 mRNA alternative polyadenylation and promotes breast cancer cell proliferation." Journal of Cell Science 134, no. 7 (2021). http://dx.doi.org/10.1242/jcs.252304.
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ABSTRACT Poly(A) polymerases add the poly(A) tail at the 3′ end of nearly all eukaryotic mRNA, and are associated with proliferation and cancer. To elucidate the role of the most-studied mammalian poly(A) polymerase, poly(A) polymerase α (PAPOLA), in cancer, we assessed its expression in 221 breast cancer samples and found it to correlate strongly with the aggressive triple-negative subtype. Silencing PAPOLA in MCF-7 and MDA-MB-231 breast cancer cells reduced proliferation and anchorage-independent growth by decreasing steady-state cyclin D1 (CCND1) mRNA and protein levels. Whereas the length of the CCND1 mRNA poly(A) tail was not affected, its 3′ untranslated region (3′UTR) lengthened. Overexpressing PAPOLA caused CCND1 mRNA 3′UTR shortening with a concomitant increase in the amount of corresponding transcript and protein, resulting in growth arrest in MCF-7 cells and DNA damage in HEK-293 cells. Such overexpression of PAPOLA promoted proliferation in the p53 mutant MDA-MB-231 cells. Our data suggest that PAPOLA is a possible candidate target for the control of tumor growth that is mostly relevant to triple-negative tumors, a group characterized by PAPOLA overexpression and lack of alternative targeted therapies.