Journal articles: 'Nonlinearities on steel structures'

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Savino, Pierclaudio, Marco Gherlone, Francesco Tondolo, and Rita Greco. "Shape-Sensing of Beam Elements Undergoing Material Nonlinearities." Sensors 21, no. 2 (January 13, 2021): 528. http://dx.doi.org/10.3390/s21020528.

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The use of in situ strain measurements to reconstruct the deformed shape of structures is a key technology for real-time monitoring. A particularly promising, versatile and computationally efficient method is the inverse finite element method (iFEM), which can be used to reconstruct the displacement field of beam elements, plate and shell structures from some discrete strain measurements. The iFEM does not require the knowledge of the material properties. Nevertheless, it has always been applied to structures with linear material constitutive behavior. In the present work, advances are proposed to use the method also for concrete structures in civil engineering field such as bridges normally characterized by material nonlinearities due to the behavior of both steel and concrete. The effectiveness of iFEM, for simply supported reinforced concrete beam and continuous beams with load conditions that determine the yielding of reinforcing steel, is studied. In order to assess the influence on displacements and strains reconstructions, different measurement stations and mesh configurations are considered. Hybrid procedures employing iFEM analysis supported by bending moment-curvature relationship are proposed in case of lack of input data in plastic zones. The reliability of the results obtained is tested and commented on to highlight the effectiveness of the approach.

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Rébillat, M., K. Ege, M. Gallo, and J. Antoni. "Repeated exponential sine sweeps for the autonomous estimation of nonlinearities and bootstrap assessment of uncertainties." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 6 (December 21, 2015): 1007–18. http://dx.doi.org/10.1177/0954406215620685.

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Measurements on vibrating structures has been a topic of interest for decades. Vibrating structures are however generally assumed to behave linearly and in a noise-free environment, which is not the case in practice. This paper provides a methodology that allows for the autonomous estimation of nonlinearities and assessment of uncertainties by bootstrap on a given vibrating structure. Nonlinearities are estimated by means of a block-oriented nonlinear model approach based on parallel Hammerstein models and on exponential sine sweeps. Estimation uncertainties are simultaneously assessed using repetitions of the input signal (multi-sine sweeps) as the input of a bootstrap procedure. Mathematical foundations and a practical implementation of the method are discussed using an experimental example. The experiment chosen here consists in exciting a steel plate under various boundary conditions with exponential sine sweeps and at different levels in order to assess the evolution of nonlinearities and uncertainties over a wide range of frequencies and input amplitudes.

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Thai, Huu-Tai, Trung-Kien Nguyen, Seunghye Lee, Vipulkumar Ishvarbhai Patel, and Thuc P. Vo. "Review of Nonlinear Analysis and Modeling of Steel and Composite Structures." International Journal of Structural Stability and Dynamics 20, no. 04 (April 2020): 2030003. http://dx.doi.org/10.1142/s0219455420300037.

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Structural steel frames exhibit significantly geometric and material nonlinearities which can be captured using the second-order inelastic analysis, also known as advanced analysis. Current specifications of most modern steel design codes, e.g. American code AISC360, European code EC3, Chinese code GB50017 and Australian code AS4100 permit the use of advanced analysis methods for the direct design of steel structures to avoid tedious member capacity checks. In the past three decades, a huge number of advanced analysis and modeling methods have been developed to predict the behavior of steel and composite frames. This paper presents a comprehensive review of their developments, which focus on beam-column elements with close attention to the way to capture geometric and material nonlinearity effects. A brief outline of analysis methods and analysis tools for frames was presented in the initial part of the paper. This was followed by a discussion on the development of displacement-based, force-based and mixed beam elements with distributed plasticity and concentrated plasticity models. The modeling of frames subjected to fire and explosion was also discussed. Finally, a review of the beam-column models for composite structures including concrete-filled steel tubular (CFST) columns, composite beams and composite frames was presented.

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Deniziak, Patryk, and Karol Winkelmann. "Influence of nonlinearities on the efficiency and accuracy of FEM calculations on the example of a steel build-up thin-walled column." MATEC Web of Conferences 219 (2018): 02010. http://dx.doi.org/10.1051/matecconf/201821902010.

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Due to the increase of computing capabilities of standard processing units, it is possible to perform complex analyses, considering a number of nonlinearities, such as geometric, material and boundary (contact) even on personal computers. In the paper, the authors have analysed the efficiency and accuracy of standard PC’s FEM calculations performed in Abaqus CAE 2017 software on the example of a critical load assessment of a thin-walled steel column element with selected nonlinearities. A cross-section shape of a built-up column used by an international steel structures manufacturer was adopted. The analysis serves to check the behavior of their product. Several types of FEM analysis, strictly based on the EN standard regulations were performed. In turn, the relation of computational time to the adopted analysis type was obtained. Moreover, the produced load values in different types of independent calculation were compared and analysed. A possible future development in the field, based mainly on full-scale experimental tests, was also highlighted.

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Koh, C. G., K. K. Ang, and P. F. Chan. "Dynamic Analysis of Shell Structures with Application to Blast Resistant Doors." Shock and Vibration 10, no. 4 (2003): 269–79. http://dx.doi.org/10.1155/2003/357969.

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This paper concerns the dynamic analysis of shell structures, with emphasis on application to steel and steel-concrete composite blast resistant doors. In view of the short duration and impulsive nature of the blast loading, an explicit integration method is adopted. This approach avoids time-consuming computations of structural stiffness matrix and solving of simultaneous nonlinear equations. Single-point quadrature shell elements are used, with numerical control to suppress spurious hourglass modes. Composite shells are handled by an appropriate integration rule across the thickness. Both material and geometric nonlinearities are accounted for in the formulation. Contact and gap problems are considered using bilinear spring elements in the finite element analysis. Numerical examples are presented for some benchmark problems and application study to blast resistant doors. Good correlation is generally obtained between the numerical results based on the software developed and the results obtained by other means including field blast tests.

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FONG, M., and S. L. CHAN. "ADVANCED ANALYSIS OF STEEL–CONCRETE COMPOSITE BEAM-COLUMNS BY REFINED PLASTIC HINGE METHOD." International Journal of Structural Stability and Dynamics 12, no. 06 (December 2012): 1250046. http://dx.doi.org/10.1142/s0219455412500460.

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Based on the second-order inelastic analysis, this paper presents a practical method of design for steel–concrete composite beam-columns that satisfies code performance requirements. The concept of second-order inelastic analysis for structures is to consider both geometric and material nonlinearities and their imperfections so that the real structural behavior can be captured and the assumption for effective lengths is not required. The refined plastic hinge approach proposed herein traces the gradual material yielding and simulates full plasticity of a cross-section. The definitions of the initial and full yield surfaces (which are used to initiate the yielding and to indicate the full plastic stage) for steel–concrete composite cross-sections, based on the cross-section analysis, are presented. The proposed method is verified in examples of isolated composite columns and frames.

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Kim, Robin E., Xingyue Piao, and Jae Hong An. "The Behavior of a Multi-Story Steel Frame Subject to Measured Fire Using Calibrated Simple Approach." Sustainability 11, no. 20 (October 11, 2019): 5607. http://dx.doi.org/10.3390/su11205607.

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Structural steels are one of the most popular construction materials with a number of merits, such as cost-effectiveness, durability, lightweight, versatility, etc. However, when exposed to a high temperature, their thermal expansion rate is high and the strength reduces substantially, making the steel structures vulnerable to fire. So far, a number of studies have been performed to understand the behavior of steel in fire. Rigorous tests, from the material to structural level, have led the advancement of modeling techniques. Among various analytical techniques, one of the most widely used approaches is the finite element modeling (FEM). While FEM can demonstrate geometrical and material nonlinearities, due to the complexity, the approach may result in high computational loads to ensure the convergence. Thus, in this paper, a simple calculation method is instead used to understand the steel frame subject to fire, in conjunction with experimentally collected temperature and displacement data. Then, at each temperature (before and after critical temperature and the formation of plastic hinges), the effect of elevated temperature on global behavior is examined using frame analysis. Results of the study have demonstrated that when structural integrity is of concern, the critical temperature of the structure must be examined in terms of fundamental characteristics of the structure.

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Parente Jr, E., G. V. Nogueira, M. Meireles Neto, and L. S. Moreira. "Material and geometric nonlinear analysis of reinforced concrete frames." Revista IBRACON de Estruturas e Materiais 7, no. 5 (October 2014): 879–904. http://dx.doi.org/10.1590/s1983-41952014000500009.

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The analysis of reinforced concrete structures until failure requires the consideration of geometric and material nonlinearities. However, nonlinear analysis is much more complex and costly than linear analysis. In order to obtain a computationally efficient approach to nonlinear analysis of reinforced concrete structures, this work presents the formulation of a nonlinear plane frame element. Geometric nonlinearity is considered using the co-rotational approach and material nonlinearity is included using appropriate constitutive relations for concrete and steel. The integration of stress resultants and tangent constitutive matrix is carried out by the automatic subdivision of the cross-section and the application of the Gauss quadrature in each subdivision. The formulation and computational implementation are validated using experimental results available in the literature. Excellent results were obtained.

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Mockutė, Agota, Enzo Marino, Claudio Lugni, and Claudio Borri. "Comparison of Nonlinear Wave-Loading Models on Rigid Cylinders in Regular Waves." Energies 12, no. 21 (October 23, 2019): 4022. http://dx.doi.org/10.3390/en12214022.

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Monopiles able to support very large offshore wind turbines are slender structures susceptible to nonlinear resonant phenomena. With the aim to better understand and model the wave-loading on these structures in very steep waves where ringing occurs and the numerical wave-loading models tend to lose validity, this study investigates the distinct influences of nonlinearities in the wave kinematics and in the hydrodynamic loading models. Six wave kinematics from linear to fully nonlinear are modelled in combination with four hydrodynamic loading models from three theories, assessing the effects of both types of nonlinearities and the wave conditions where each type has stronger influence. The main findings include that the nonlinearities in the wave kinematics have stronger influence in the intermediate water depth, while the choice of the hydrodynamic loading model has larger influence in deep water. Moreover, finite-depth FNV theory captures the loading in the widest range of wave and cylinder conditions. The areas of worst prediction by the numerical models were found to be the largest steepness and wave numbers for second harmonic, as well as the vicinity of the wave-breaking limit, especially for the third harmonic. The main cause is the non-monotonic growth of the experimental loading with increasing steepness due to flow separation, which leads to increasing numerical overpredictions since the numerical wave-loading models increase monotonically.

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Rong, Qin, Zhonghui Zhao, Lanhui Guo, Xiaomeng Hou, Li Lin, and Hongtao Bi. "Seismic Performance of CFST Frame-Steel Plate Shear Walls Connected to Beams Only." Shock and Vibration 2021 (August 13, 2021): 1–13. http://dx.doi.org/10.1155/2021/5850073.

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The safety and cost of structures composed of concrete-filled steel tube (CFST) frame-steel plate shear walls (SPSWs) with two-side connections are governed by the seismic performance. The response modification factor R and displacement amplification factor Cd are important seismic performance factors. In this paper, nonlinear seismic responses of 10-story, 15-story, and 20-story CFST frame-SPSWs (CFST-SPSWs) are studied. A nonlinear finite element model which includes both material and geometric nonlinearities is developed using the finite element software OpenSees for this study. The accuracy of model was validated by comparing with experimental results. Nonlinear seismic analysis shows that CFST-SPSWs, in high seismic region, behave in a stable and ductile manner. Also, R and Cd of CFST-SPSWs were evaluated for the structure models using incremental dynamic analysis (IDA), and the average values of 3.17 and 3.05 are recommended, respectively. The recommended R value is greater than the value (2.8) in the “Chinese Code for seismic design of buildings” for composite structures, indicating the code is conservative. The structural periods provided by current code are generally lower than the periods calculated by finite element analysis. Research results show that R and Cd increase with increasing story number, span number, and structural period. Ductility reduction factor Rμ increases with increasing span number and decreasing story number. Overstrength factor Rs increases with increasing story number and decreasing span number.

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Freire, A. M. S., J. H. O. Negrão, and A. V. Lopes. "Geometrical nonlinearities on the static analysis of highly flexible steel cable-stayed bridges." Computers & Structures 84, no. 31-32 (December 2006): 2128–40. http://dx.doi.org/10.1016/j.compstruc.2006.08.047.

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TAKEDA, HACHIRO, EIICHI WATANABE, and RYO KUNISHI. "INELASTIC REPETITIVE SHEAR AND FLEXURAL BUCKLING OF PLATE GIRDERS." International Journal of Structural Stability and Dynamics 04, no. 01 (March 2004): 105–24. http://dx.doi.org/10.1142/s021945540400115x.

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In the Great Hanshin–Awaji earthquake of 1995, the phenomena of repetitive inelastic buckling were observed in many steel girders including horizontal girders of portal steel piers on elevated highways. The authors have been interested in the ability of steel girders to dissipate the hysteretic plastic strain energy due to such repetitive buckling of steel girders for earthquake-resistance design. This paper is focused on the repetitive buckling behavior of eight steel plate girders under inelastic shear or the combined shear and bending due to a concentrated point load adopting two independent cyclic loading patterns. The model girders were selected considering the combined variations of flange thickness, flange width and depth-to-thickness ratio of the web. Good correlations were found between the results of tests and finite element analyses using shell elements considering the material and geometrical nonlinearities in the repetitive inelastic buckling behavior of plate girders.

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Nichols, J. M., S. T. Trickey, M. Seaver, S. R. Motley, and E. D. Eisner. "Using Ambient Vibrations to Detect Loosening of a Composite-to-Metal Bolted Joint in the Presence of Strong Temperature Fluctuations." Journal of Vibration and Acoustics 129, no. 6 (October 3, 2006): 710–17. http://dx.doi.org/10.1115/1.2753502.

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We present an approach for detecting damage-induced nonlinearities in structures. The method first involves the creation of surrogate data sets conforming to an appropriate null hypothesis (no damage). The second step is to then compare some nonlinear “feature” extracted from the original data to those extracted from the surrogates. Statistically significant differences suggest evidence in favor of the alternative hypothesis, damage. Using this approach we show how loose connections can be detected using ambient “wave” forcing, conforming to the Pierson-Moskowitz distribution, as the source of excitation. We also demonstrate the ability of this technique to operate without a recorded baseline data set and in the presence of widely varying temperatures. The structure in this case is a thick, composite beam bolted to a steel frame. Data are collected using an optical strain sensing system. For this experiment we are able to reliably detect the presence of a loosened bolt.

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Anbarasu, M., and M. Venkatesan. "Behaviour of cold-formed steel built-up I-section columns composed of four U-profiles." Advances in Structural Engineering 22, no. 3 (September 7, 2018): 613–25. http://dx.doi.org/10.1177/1369433218795568.

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This work reports numerical results concerning the cold-formed steel built-up I-section columns composed of four U-profiles under axial compression. A finite element model is developed by using the software program ABAQUS. The developed model includes geometric, material nonlinearities and geometric imperfections. The finite element model was verified against the experimental results reported in the cold-formed steel built-up open section columns. In the parametric study, the sections are analysed with several cross-sectional dimension ratios and lengths, in order to assess their influence on the buckling behaviour and ultimate strength of cold-formed steel built-up I-section columns. After presenting and discussing the numerical parametric results, the article shows that the current direct strength method in the North American Specification for cold-formed steel compression members design curve fails to predict adequately the ultimate strength of some of the columns analysed and addresses the modification proposed on current direct strength method curves, providing improved predictions of all the numerical ultimate strength available. The proposed method is also assessed by reliability analysis.

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Bhowmick, Anjan K., Gilbert Y. Grondin, and Robert G. Driver. "Performance of Type D and Type LD steel plate walls." Canadian Journal of Civil Engineering 37, no. 1 (January 2010): 88–98. http://dx.doi.org/10.1139/l09-126.

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A finite element model is developed to study the behaviour of unstiffened steel plate walls. The model includes both material and geometric nonlinearities and strain rate effects. The model is first validated using the results from quasistatic and dynamic experimental programs. The validated finite element model is then used to study the performance of four storey and eight storey steel plate walls with moment-resisting beam-to-column connections under spectrum compatible seismic records for Vancouver and Montreal. Two different steel plate wall types defined in the current Canadian standard CAN/CSA-S16–01 are considered, namely, Type D (ductile) and Type LD (limited-ductility) plate walls. All the Type D walls, designed according to the capacity design provisions, exhibit better inelastic seismic responses than the Type LD plate walls. The analyses of eight storey steel plate walls show that in high seismic regions, such as Vancouver, medium- to high-rise Type LD plate walls may exhibit yielding in columns in intermediate floors. The study also shows that in more moderate seismic regions, like Montreal, Type LD plate walls behave in a stable and ductile manner and can be used for low- to medium-rise buildings.

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Al Fakih, Kamal, Siew Choo Chin, and Shu Ing Doh. "Behavior of Extended End-Plate Steel Beam to Column Connections." Open Civil Engineering Journal 12, no. 1 (August 13, 2018): 250–62. http://dx.doi.org/10.2174/1874149501812010250.

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Background: The main objective of this study is to simulate the behaviour of steel beam-to-column connections using the computer package of Finite Element Analysis (FEA) known as “ABAQUS”. Objective: This paper presents the investigations of extended End-Plate connections (EP). A one-model segment is examined under the impact of concentrated load and the exclusive boundary conditions were tested. The analysis of the nonlinear behaviour of the connection is a complicated science and needs to use programs to solve this problem. Experimental works are normally conducted for this type of studies which used more of money, time and effort. Therefore, with the availability of simulation applications, these problems can be addressed. Results and Conclusion: The results of the evaluation were compared with the experimental data from the available literature. In this case, nonlinearity materials were used. A sample study on EP connections was carried out using both material and geometric nonlinearities. The comparison of FEA results with corresponding experimental results confirms the correlation and convergence between them.

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Xu, Xiao Qing, Yu Qing Liu, Jun He, and Jie Luo. "Numerical Simulation on Failure Process of Rubber-Sleeved Headed Stud Shear Connector." Key Engineering Materials 577-578 (September 2013): 617–20. http://dx.doi.org/10.4028/www.scientific.net/kem.577-578.617.

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Rubber-sleeved headed stud shear connector is flexible shear connector used in steel-concrete composite structures. In this work, nonlinear finite element model has been developed to simulate the failure process of the shear connector under shear loading. The stress distribution, deformation, crack propagation and failure mode were analyzed. The material nonlinearities of rubber, headed stud, concrete were considered in the material model. The rubber was assumed as a perfect material with no defect, and a modified reduced polynomial form of strain energy including an energy limiter and a new constant was introduced into the user material subroutine VUANISOHYPER-INV of ABAQUS software. Damaged plasticity model was used to model the concrete material. A tri-linear elastic-plastic curve was used in stud material model. Comparing the results obtained from the finite element analysis with those from push-out test, good agreement is highlighted in the capacity, ductility and failure mode of rubber-sleeved headed stud shear connector.

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SHANMUGAM, N. E., and B. LAKSHMI. "EFFECT OF KEY PARAMETERS ON STRENGTH OF IN-FILLED STEEL-CONCRETE COMPOSITE COLUMNS." International Journal of Structural Stability and Dynamics 05, no. 02 (June 2005): 217–39. http://dx.doi.org/10.1142/s0219455405001520.

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This paper is concerned with the detailed study on the behavior of steel tubular columns in-filled with concrete. Moment–curvature–thrust relationships are generated for column cross-sections by an iterative process. Nonlinear equilibrium equations which include geometric and material nonlinearities are solved by an incremental-iterative numerical scheme based on generalized displacement control (GDC) method. The analytical model is used to investigate the effect of various parameters that could influence the behavior and ultimate load. Column end restraints are also considered as one of the parameters. The variables selected for the study cover a wide range of parameters arising from various loading conditions and column geometries.

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Batchelor, B. deV, and Jayanth Srinivasan. "Calculation of stress in prestressing steel at ultimate conditions." Canadian Journal of Civil Engineering 16, no. 4 (August 1, 1989): 576–82. http://dx.doi.org/10.1139/l89-088.

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This paper reviews different methods available for the calculation of stress in prestressing steel at ultimate, ƒps, and the methods are evaluated using a nonlinear analysis computer program. The development of a nonlinear model for the analysis of partially prestressed concrete flexural members is described. The model takes the material nonlinearities into account by the use of appropriate stress–strain relationships for steel and concrete. A parametric study of partially prestressed beams was conducted to study the effect of various parameters on stress in prestressing steel at ultimate conditions. Two types of sections, rectangular and T sections, were studied. The prediction equation, recommended in the Canadian Code Can3-A23.3-M84, for calculating the stress in prestressing steel at ultimate is found to be very conservative for all the cases studied, which covered all possible ranges of partial prestressing ratio. The present restriction in the Canadian Code, for the use of their prediction equation only when the ratio of the neutral axis depth, Cu, to the depth of the centroid of prestressing steel, dps, is less than or equal to 0.3, is found to be too restrictive. An alternative equation for ƒps, suggested by Loov, is found to be more suitable than the present equation in the Canadian Code; however, a more practical upper limit for cu/dps ratio is suggested in the paper. It is shown that the proposed equation can be used conservatively over the complete range of partially prestressed concrete. Key words: analysis, concrete (prestress), flexure, partial prestressing, prestressing, strain, stress, steel.

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Han, Hesheng, Lun Liu, and Dengqing Cao. "Forced Vibration of a Cable-Stayed Beam by Green’s Function Approach." International Journal of Structural Stability and Dynamics 20, no. 04 (April 2020): 2050055. http://dx.doi.org/10.1142/s0219455420500558.

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A method based on Green’s functions is proposed to study the steady-state dynamic responses of a cable-stayed beam subjected to distributed and/or concentrated loadings. The cable’s initial sag and damping effects are considered. Also, the quadratic and cubic nonlinearities due to the dynamic strain of the cable are taken into account. The nonlinear governing equations of the system are solved by the perturbation method, and the Laplace transformation is employed to derive the Green’s functions for the beam and cable with specified boundary conditions. Then the closed form solution of the linear system and the perturbation analytical solution of the nonlinear system are given in an integral form based on those Green’s functions. The difference between the Green’s functions for the linear and nonlinear systems is caused by the nonlinear boundary conditions. The natural frequencies of the cable-stayed beam calculated by the proposed method are compared with those in the literature to illustrate the validity of the present approach. Particularly, the cable’s dynamic strain effects on the symmetric property of the Green’s functions are discussed. The effects of the nonlinear terms on the amplitude of the Green’s functions and vibration are investigated, along with that of damping. The technique presented should find its applicability for other complex structures, such as cable-stayed bridges and steel structures.

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Martin, A., S. F. Stiemer, and P. Osterrieder. "Ultimate load capacity of square shear plates with circular perforations." Canadian Journal of Civil Engineering 15, no. 3 (June 1, 1988): 470–76. http://dx.doi.org/10.1139/l88-063.

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Working platforms and support caissons of offshore steel structures are often designed with plate boxes or plate girders. The important shear walls or shear webs must often be perforated to allow utilities, etc., to pass through. The failure mode of these large perforated shear panels is typically shear buckling, usually in the plastic range. The paperpresents results of a finite element buckling analysis with inelastic material behaviour and gives general guidelines for the ultimate capacity design of perforated shear plates. The parameters affecting the ultimate capacity of square plates with circular perforations under uniform shear stress were investigated using the incremental structural analysis program NISA83. Nonlinearities in material properties and geometry were taken into account in the calculation of ultimate capacities of each perforated shear plate.The parameters investigated in the study were hole size for a concentric hole and hole location for a constant hole size. Only single unreinforced round holes were considered. Three capacities were calculated for each variation of these parameters: the ultimate in-plane capacity, the elastic buckling capacity, and the ultimate elastic-plastic buckling capacity.In order to check the input data and to provide concise display of the results, a graphic postprocessor was developed as part of the research. The program NISPLOT uses colour graphics to generate plots of the nodes, element mesh, the deflected shape, and stress patterns of the loaded plates. The plots were reduced to black and white for this paper. Key words: girders, holes, steel, ultimate capacity, buckling.

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Varnavaa, Varnavas, and Petros Komodromos. "Assessing the effect of inherent nonlinearities in the analysis and design of a low-rise base isolated steel building." Earthquakes and Structures 5, no. 5 (November 25, 2013): 499–526. http://dx.doi.org/10.12989/eas.2013.5.5.499.

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Al-Dujele, Rana, and Katherine Ann Cashell. "Design and analysis of concrete-filled tubular flange girders under combined loading." Advances in Structural Engineering 24, no. 11 (March 27, 2021): 2512–28. http://dx.doi.org/10.1177/13694332211001520.

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This paper is concerned with the behaviour of concrete-filled tubular flange girders (CFTFGs) under the combination of bending and tensile axial force. CFTFG is a relatively new structural solution comprising a steel beam in which the compression flange plate is replaced with a concrete-filled hollow section to create an efficient and effective load-carrying solution. These members have very high torsional stiffness and lateral torsional buckling strength in comparison with conventional steel I-girders of similar depth, width and steel weight and are there-fore capable of carrying very heavy loads over long spans. Current design codes do not explicitly include guidance for the design of these members, which are asymmetric in nature under the combined effects of tension and bending. The current paper presents a numerical study into the behaviour of CFTFGs under the combined effects of positive bending and axial tension. The study includes different loading combinations and the associated failure modes are identified and discussed. To facilitate this study, a finite element (FE) model is developed using the ABAQUS software which is capable of capturing both the geometric and material nonlinearities of the behaviour. Based on the results of finite element analysis, the moment–axial force interaction relationship is presented and a simplified equation is proposed for the design of CFTFGs under combined bending and tensile axial force.

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Kato, Shiro, and Yutaka Niho. "Evaluation of Load Factor to Be Applied in Buckling Design of Cylindrical Lattice Shells Under Asymmetric Snow Load." Journal of the International Association for Shell and Spatial Structures 61, no. 3 (September 1, 2020): 211–26. http://dx.doi.org/10.20898/j.iass.2020.005.

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The load factor is one of the keys in anti-buckling design for safety together for construction cost, and studies have been becoming demanded in a recent situation that super large and super light spatial structures have been constructed. This paper investigates the relationship between reliability index β and snow load factor γs for anti-buckling design of a simply supported cylindrical lattice shell roof under simultaneous action of both dead load and asymmetric snow load. The cylindrical lattice shell analyzed is composed of an equilateral triangle grid of which members are of steel circular hollow sections. Members are connected rigidly to nodes at their both ends. The snow distribution as a main target is assumed in a way that the snow depth on the half of the arch-like roof is half of the amount on the other half roof. The snow fall depth is here assumed 50cm evaluated as 100-year return period, and its probability is assumed as Gumbel distribution with 100-year reference period. The probability distribution of buckling strength Pcr including geometrical and material nonlinearities is approximately evaluated based on a first-order perturbation. The reliability is calculated based on AFOSM, and the relationship in a form of β to γs is finally expressed for design use.

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Meleka, N. N., M. A. Safan, A. A. Bashandy, and A. S. Abd-Elrazek. "Repairing and Strengthening of Elliptical Paraboloid Reinforced Concrete Shells with Openings." Archives of Civil Engineering 59, no. 3 (September 1, 2013): 401–20. http://dx.doi.org/10.2478/ace-2013-0022.

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Abstract This investigation is carried out to evaluate the repair and strengthening the techniques of elliptical paraboloid reinforced concrete shells with openings. An experimental program of several different techniques in repair and strengthening is executed. The materials, which are considered for strengthening, are; Glass fiber reinforced polymers GFRP at different position of the shell bottom surface, steel strip and external tie. They loaded by four concentrated loads affected on the corners of the opening. The initial and failure loads as well as the crack propagation for the tested shells at different loading stages, deflections and failure load for repaired and shells are recorded. A non-linear computer program based on finite element techniques is used to study the behavior of these types of shells. Geometric and materials nonlinearities are considered in the analysis. The efficiency and accuracy of computer program are verified by comparing the program results with those obtained experimentally for the control shell with opening and strengthened shells.

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Hinman, John, Vong Toan, and Steve Thoman. "Seismic Retrofit of 1958 Carquinez Bridge." Transportation Research Record: Journal of the Transportation Research Board 1624, no. 1 (January 1998): 54–63. http://dx.doi.org/10.3141/1624-07.

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The 1021-m (3,350-ft) long steel through truss bridge carrying the east-bound lanes of Interstate 80 across the western end of the Carquinez Strait about 40 km (25 mi) north of San Francisco opened to traffic in 1958. It was the first major highway bridge in the United States to use high-strength (T1) steel, the first to use welded built-up members, and the first to use high-strength bolted connections. These “firsts,” combined with the size of the bridge and the traffic demands, presented a formidable challenge to the retrofit design team. The retrofit objective was to prevent collapse of the bridge during an earthquake with an expected mean return period in the range of 1,000 to 2,000 years. Under this noncollapse criterion, significant damage to the bridge, such as yielding and buckling of members, was considered acceptable. It was important, then, that a measure of acceptable damage be defined and that the postyield behavior of the structure be both very predictable and very ductile. A preliminary design was prepared based on an elastic analysis with geometric non-linearities. The retrofit design was then examined by incorporating material nonlinearities into the model; adjustments to the retrofit design were required in some isolated areas. Design issues that the team addressed included connections for loads as high as 60 to 50 kN (13,500 kips); local buckling of thin-walled, high-strength members; postyield behavior of major load-carrying steel members; rocking of rigid A-frame tower assemblies; and an expansion joint for an 8-ft movement rating.

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Misiūnaitė, Ieva, Algirdas Juozapaitis, and Alfredas Laurinavičius. "COMPREHENSIVE STUDY ON UNDERSLUNG GIRDER BRIDGE UNDER DIFFERENT LOADING CONDITIONS." Baltic Journal of Road and Bridge Engineering 12, no. 1 (March 24, 2017): 21–29. http://dx.doi.org/10.3846/bjrbe.2017.03.

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The comprehensive study on the structural behaviour of underslung girder bridge is examined in this study through both numerical modelling and experimental 3D model tests. The structural design of steel bridges in many cases is governed by their ability to withstand asymmetric loading conditions. Three different symmetric and asymmetric load cases were investigated to capture the deformational and flexural response of the main girder. It was found that under distributed load the structural response of underslung girder bridge was similar to beam-column with intermediate elastic supports. The numerical model was validated against experimental data with good agreement perceived, allowing an extensive parametric study to be performed. The observed influence of initial geometric imperfections and nonlinearities are discussed. It was found that symmetric load governs the ultimate limit state. However, the asymmetric one takes over in the case of serviceability. Finally, the study presented herein summarises experimental investigations, numerical simulations and design proposals obtained through the recent few years research program, carried on to deepen the knowledge on the structural behaviour of underslung girder bridges.

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Liu, Yi, and J. L. Dawe. "Analytical modeling of masonry load-bearing walls." Canadian Journal of Civil Engineering 30, no. 5 (October 1, 2003): 795–806. http://dx.doi.org/10.1139/l03-036.

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An analytical technique was developed and encoded for computer application to study the behaviour of concrete masonry load-bearing walls under various loading conditions. Both geometrical and material nonlinearities to account for the moment magnification effect and the degradation of material stiffness are included in the development. Effects of vertical reinforcing steel, masonry tensile cracking, and compressive crushing are included directly in the momentcurvature relationship, which is used in the determination of element stiffnesses at successive load increments. A parametric study was conducted following verification of the analytical model by comparing results with experimental test data. Effective flexural rigidity (EIeff) values at failure were obtained analytically and compared with values suggested in the Canadian masonry code CSA-S304.1-M94. It was concluded that CSA-S304.1-M94 tends to underestimate EIeff values for reinforced walls and thus leads to a conservative design over a range of parameters. Based on approximately 500 computer model tests, a lower bound bilinear limit for the effective rigidity of reinforced masonry walls was established. This limit is believed to provide an accurate and realistic estimate of EIeff.Key words: walls, load bearing, masonry, analytical, nonlinear, rigidity, stressstrain, momentcurvature.

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29

Davidson, James S., and Chai H. Yoo. "Effects of Distortion on Strength of Curved I-Shaped Bridge Girders." Transportation Research Record: Journal of the Transportation Research Board 1845, no. 1 (January 2003): 48–56. http://dx.doi.org/10.3141/1845-06.

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The curved I-shaped plate girders used in bridges with curved alignment are subjected to forces that cause significant distortion of the cross section during construction and during application of live loads after the deck has hardened. Furthermore, the addition of curvature reduces the vertical bending stiffness, increases deflection nonlinearities, and changes stability characteristics of behavior. Although the design equations of the AASHTO Guide Specifications for Horizontally Curved Highway Bridges are formulated to address these behavioral issues, design and construction engineers often are not familiar with the difficulties curvature introduces and do not understand the relationship between distortion and deflection amplification with the design equations. Analytical research conducted as part of the FHWA Curved Steel Bridge Research Project was used to highlight and describe the effects of curvature on the strength and stability of curved I-girder bridge superstructures. Issues described include the following: ( a) effects of cross-frame and diaphragm spacing on system behavior, ( b) effects of curvature on the lateral-torsional stability of curved I-shaped beams, ( c) effects of warping stresses on flange buckling, ( d) effects of curvature on web behavior, and ( e) effects of curvature on initiation and propagation of yield stresses in the girders of curved I-girder frames.

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Roca, P., E. Mirambell, and J. Costa. "Geometric and Material Nonlinearities in Steel Plates." Journal of Structural Engineering 122, no. 12 (December 1996): 1427–36. http://dx.doi.org/10.1061/(asce)0733-9445(1996)122:12(1427).

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31

Gea, Hae Chang, and Jianhui Luo. "Topology optimization of structures with geometrical nonlinearities." Computers & Structures 79, no. 20-21 (August 2001): 1977–85. http://dx.doi.org/10.1016/s0045-7949(01)00117-1.

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32

Houver, S., A. Lebreton, T. A. S. Pereira, G. Xu, R. Colombelli, I. Kundu, L. H. Li, et al. "Giant optical nonlinearity interferences in quantum structures." Science Advances 5, no. 10 (October 2019): eaaw7554. http://dx.doi.org/10.1126/sciadv.aaw7554.

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Second-order optical nonlinearities can be greatly enhanced by orders of magnitude in resonantly excited nanostructures. These resonant nonlinearities continually attract attention, particularly in newly discovered materials. However, they are frequently not as heightened as currently predicted, limiting their exploitation in nanostructured nonlinear optics. Here, we present a clear-cut theoretical and experimental demonstration that the second-order nonlinear susceptibility can vary by orders of magnitude as a result of giant destructive, as well as constructive, interference effects in complex systems. Using terahertz quantum cascade lasers as a model source to investigate interband and intersubband nonlinearities, we show that these giant interferences are a result of an unexpected interplay of the second-order nonlinear contributions of multiple light and heavy hole states. As well as of importance to understand and engineer the resonant optical properties of nanostructures, this advanced framework can be used as a novel, sensitive tool to elucidate the band structure properties of complex materials.

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33

Huang, Yifeng, and Paul D. Sclavounos. "Nonlinear Ship Motions." Journal of Ship Research 42, no. 02 (June 1, 1998): 120–30. http://dx.doi.org/10.5957/jsr.1998.42.2.120.

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A nonlinear numerical method has been developed to compute motion responses for a ship traveling in steep ambient waves. The method is based on an approximate theory and is an extension to a well-established linear time-domain numerical method. The nonlinear solution is found to be greatly improved over the classical linear and quasi-nonlinear solutions, in comparison to experimental measurements for conventional commercial ships. Through this study, it is also demonstrated that the free surface hydrodynamic nonlinearities are at least as important as, if not more than, the hydrostatic and Froude-Krylov nonlinearities. Stability, consistency and convergence for the nonlinear method are also addressed.

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Zhu, Yong, Yun Zhou, and He Zhu. "Numerical Simulation of Bolted-Steel Plates Strengthened Coupling Beams." Advanced Materials Research 163-167 (December 2010): 3677–81. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.3677.

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One reinforced concrete coupling beam and two strengthened reinforced concrete coupling beams by bolted steel plates are analyzed by nonlinear finite element method. Two-dimensional finite element model is employed with material nonlinearities and geometrical nonlinearities. A special ring region, which simulates the slip effect between concrete and steel plates, is developed an incorporated into the numerical analysis model. The load-displacement relationship, cracking/crushing type and steel plates internal are compared and found to be in good agreement with those in test.

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35

Chili, W. K., S. Galea, and R. Jones. "The role of material nonlinearities in composite structures." Composite Structures 38, no. 1-4 (May 1997): 71–81. http://dx.doi.org/10.1016/s0263-8223(97)00043-3.

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36

Zhang, Jun, and Bruce Ellingwood. "SFEM for Reliability of Structures with Material Nonlinearities." Journal of Structural Engineering 122, no. 6 (June 1996): 701–4. http://dx.doi.org/10.1061/(asce)0733-9445(1996)122:6(701).

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37

Heuer, Rudolf. "Vibrations of linear structures with spatial local nonlinearities." PAMM 6, no. 1 (December 2006): 309–10. http://dx.doi.org/10.1002/pamm.200610136.

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38

Kaklauskas, Gintaris. "METHODS AND CONSTITUTIVE MODELS FOR DEFORMATIONAL ANALYSIS OF FLEXURAL REINFORCED CONCRETE MEMBERS/LENKIAMŲJŲ GELŽBETONINIŲ ELEMENTŲ DEFORMATYVUMO VERTINIMO METODAI IR FIZIKINIAI MODELIAI." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 6, no. 5 (October 31, 2000): 329–38. http://dx.doi.org/10.3846/13921525.2000.10531610.

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The paper reviews both analytical and finite element methods for deformational analysis of flexural reinforced concrete members subjected to short-term loading. In a state-of-the-art summary of various proposed stress-strain relationships for concrete and reinforcement, a special emphasis is made on critical survey of modelling post-cracking behaviour of tensile concrete in smeared crack approach. Empirical code methods of different countries (American Code (ACI Committee 318 [7]), the Eurocode EC2 [8], and the Russian (old Soviet) Code (SNiP 2.03.01-84 [5]) for deflection calculation of flexural reinforced concrete members are briefly described in section 2. Although these methods are based on different analytical approaches, all of them proved to be accurate tools for deflection assessment of members with high and average reinforcement ratios. It should be noted that these methods have quite a different level of complexity since the Russian Code method employs a great number of parameters and expressions whereas the ACI and EC2 methods are simple and include only basic parameters. Approaches of numerical simulation and constitutive relationships are discussed in Chapter 3. All numerical simulation research can be classified into two large groups according to two different approaches for crack modelling (subsection 3.1): 1) Discrete cracking model. In this approach, cracks are traced individually as they progressively alter the topology of the structure. 2) Smeared cracking model. The cracked concrete is assumed to remain a continuum, ie the cracks are smeared out in the continuous fashion. After cracking, the concrete becomes orthotropic with one of the material axes being oriented along the direction of cracking. Constitutive relationships for steel and plain concrete are presented in subsection 3.2. A special emphasis is made on critical survey of modelling post-cracking behaviour of tensile concrete in smeared crack approach. It has been concluded that although empirical design codes of different countries ensure safe design, they do not reveal the actual stress-strain state of cracked structures and often lack physical interpretation. Numerical methods which were rapidly progressing within last three decades are based on universal principles and can include all possible effects such as material nonlinearities, concrete cracking, creep and shrinkage, reinforcement slip, etc. However, the progress is mostly related to the development of mathematical apparatus, but not material models or, in other words, the development was rather qualitative than quantitative. Constitutive relationships often are too simplified and do not reflect complex multi-factor nature of the material. Existing constitutive relationships for concrete in tension do not assure higher statistical accuracy of deflection estimates for flexural reinforced concrete members in comparison to those obtained by empirical code methods. The author has developed integral constitutive model for deformational analysis of flexural reinforced concrete members [36]. The integral constitutive model consists of traditional constitutive relationships for reinforcement and compressive concrete and the integral constitutive relationship for cracked tensile concrete which accumulates cracking, tension stiffening, reinforcement slippage and shrinkage effects. This constitutive model can be applied not only in a finite element analysis, but also in a simple iterative technique based on classical principles of strength of materials extended to layered approach.

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39

Mesic, Esad. "Analysis of timber frames with localized nonlinearities." Facta universitatis - series: Architecture and Civil Engineering 2, no. 5 (2003): 307–20. http://dx.doi.org/10.2298/fuace0305307m.

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A methodology of nonlinear analysis of timber frame structures with flexible connections has been developed in this paper. The methodology is based on the results of experimental investigation of connections behavior under static and cycling loading. The adopted numerical method is based on the concept of localized nonlinearity which facilitates the reproduction of the experimentally determined connections behavior in the analysis of frame structures. The methodology is also applicable to other types of timber structures.

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40

Novotný, Ladislav. "Finite Element Simulation of Bending of Steel Bar Including Plasticity." Applied Mechanics and Materials 816 (November 2015): 182–87. http://dx.doi.org/10.4028/www.scientific.net/amm.816.182.

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The article presents the use of finite element method for the simulation of cold forming process. The numerical simulation of a real technological operation of bending a rod by an industrial bender. Within the simulation, different types of nonlinearities, namely of material nonlinearity, resulting from the flexible plastic material properties of the rod, are considered, geometric nonlinearities result from large displacement and nonlinear contact. This paper briefly describes the elastic – plastic material model. Numerical analysis confirmed the appropriateness of the use of finite element method in the simulation of technological operations and the eventual possible optimization of these processes.

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41

Deierlein, G. G. "Steel-framed structures." Progress in Structural Engineering and Materials 1, no. 1 (September 1997): 10–17. http://dx.doi.org/10.1002/pse.2260010105.

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42

Johansson, Bernt, and Milan Veljkovic. "Steel plated structures." Progress in Structural Engineering and Materials 3, no. 1 (January 2001): 13–27. http://dx.doi.org/10.1002/pse.59.

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43

Svetlik, M., K. Slama, and J. Kralovec. "Steel structures diagnostic." NDT & E International 27, no. 4 (January 1994): 219. http://dx.doi.org/10.1016/0963-8695(94)90555-x.

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KHOO, I. C., S. LEE, P. LOPRESTI, R. G. LINDQUIST, and H. LI. "ISOTROPIC LIQUID CRYSTALLINE FILM AND FIBER STRUCTURES FOR OPTICAL LIMITING APPLICATION." Journal of Nonlinear Optical Physics & Materials 02, no. 04 (October 1993): 559–75. http://dx.doi.org/10.1142/s0218199193000346.

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The principal optical nonlinearities of isotropic liquid crystals are reviewed, and their potentials for all-optical limiting and switching applications are assessed. Our dynamic grating studies of a class of isotropic liquid crystals show that, in the nanosecond and longer time scales, the principal mechanisms for nonlinearities are laser induced ordering (molecular orientations), thermal and density fluctuations. We report optical limiting results obtained with bulk thin film and optical fiber fabricated from these isotropic crystals.

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45

Khurgin, J. "Coulomb enhancement of ultrafast nonlinearities in quantum-well structures." Journal of the Optical Society of America B 9, no. 1 (January 1, 1992): 157. http://dx.doi.org/10.1364/josab.9.000157.

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46

Marchesiello, S., and L. Garibaldi. "Subspace-Based Identification of Nonlinear Structures." Shock and Vibration 15, no. 3-4 (2008): 345–54. http://dx.doi.org/10.1155/2008/873183.

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Conventional linear estimators give results contaminated in presence of nonlinearities and the extraction of underlying linear system properties is thus difficult. To overcome this problem, the implementation of a recently developed method, called Nonlinear Subspace Identification (NSI), is considered in this paper, by using the perspective of nonlinearities as unmeasured internal feedback forces. Although its formulation is very simple, particular care has to be taken to reduce the ill-conditioning of the problem, in order to find numerically stable solutions. To this purpose, the robustness and the high numerical performances of the subspace algorithms are successfully exploited, as shown by the implementation of the proposed method on simulated multi-degree-of-freedom systems with typical nonlinear characteristics as well as on an experimental case. These examples demonstrate that the application of subspace algorithms to nonlinear system identification gives better conditioning and computational efficiency with respect to the most recent nonlinear techniques. Moreover, the capability of the NSI method of simultaneously dealing with several nonlinear terms, with a light computational effort, may be also exploited in those situations where no a priori knowledge of the location and the type of nonlinearities is given, being this method well capable of detecting the contribution of the dominant nonlinearities.On the basis of the results discussed in this paper, and compared with those of other well-assessed nonlinear techniques, the proposed method appears having the chances to become a robust procedure to be widely exploited in many industrial fields, being its capability of separating linear and nonlinear contribution terms widely requested in mechanical and civil engineering field.

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47

Szalai, Robert. "Modelling elastic structures with strong nonlinearities with application to stick–slip friction." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470, no. 2161 (January 8, 2014): 20130593. http://dx.doi.org/10.1098/rspa.2013.0593.

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An exact transformation method is introduced that reduces the governing equations of a continuum structure coupled to strong nonlinearities to a low-dimensional equation with memory. The method is general and well suited to problems with isolated discontinuities such as friction and impact at point contact. It is assumed that the structure is composed of two parts: a continuum but linear structure and finitely many discrete but strong nonlinearities acting at various contact points of the elastic structure. The localized nonlinearities include discontinuities, e.g. the Coulomb friction law. Despite the discontinuities in the model, we demonstrate that contact forces are Lipschitz continuous in time at the onset of sticking for certain classes of structures. The general formalism is illustrated for a continuum elastic body coupled to a Coulomb-like friction model.

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Huang, Yuan, Wei Jian Yi, and Jian Guo Nie. "Nonlinear Analysis of CFT Composite Frame with Floor Slab." Advanced Materials Research 243-249 (May 2011): 1168–72. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1168.

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Nonlinear finite element (FE) analysis models of CFT composite frames with floor slab were established by Msc.Marc to investigate the seismic behavior of composite frames. A number of material nonlinearities and contact nonlinearities, as well as geometry nonlinearities, were taken into account, including elastoplastic properties of steel and concrete, concrete cracking and tension stiffening, steel fracture, interface slip between concrete slabs and steel beams, P-D effects etc. The elasto-plastic behavior, as well as fracture and post-fracture behavior, of the FE analysis models agreed well with those of the test specimens. The beam and panel zone deformation of the analysis models is also in good agreement with that of the test specimen. It is concluded that FE analysis is useful not only for monotonic load analysis but also for cyclic load analysis. It is a helpful tool to expand the information on seismic behavior of composite frame.

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González‐de‐León, Isabel, Itsaso Arrayago, and Esther Real. "Interaction of geometric and material nonlinearities in stainless steel frames." ce/papers 4, no. 2-4 (September 2021): 2149–57. http://dx.doi.org/10.1002/cepa.1533.

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Isaacson, Michael de St Q. "Recent advances in the computation of nonlinear wave effects on offshore structures." Canadian Journal of Civil Engineering 12, no. 3 (September 1, 1985): 439–53. http://dx.doi.org/10.1139/l85-052.

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The present paper provides a review of recent research on various nonlinearities that arise in ocean wave interactions with offshore structures. These include nonlinearities associated with the incident waves alone, the response of slender structural members to waves, and the nonlinear diffraction problem involving wave interactions with large structures. Emphasis is given to areas of current research into two particular nonlinear problems. One concerns an investigation into alternative approximations to the Morison equation for flexible structures and the other concerns the numerical simulation of nonlinear wave diffraction around large structures. Key words: diffraction, hydrodynamics, nonlinear flow, ocean engineering, offshore structures, waves.

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Journal articles on the topic 'Nonlinearities on steel structures'

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