Shen Zuyan

A hysteresis model for plane steel members with damage cumulation effects

Abstract In order to consider the effects of damage cumulation on the structural responses, a damage model for steel structural members based on plastic strains of the material has been proposed. Adopting the hypotheses of elasto-plastic damage hinges and the damage concentrated at the ends of a steel member, a hysteresis model for plane steel members with effects of damage cumulation has been built. The proposed model can consider the following effects: strain hardening effect and strength degeneration effect caused by damage cumulation. Finally, by means of this model, an elasto-plastic stiffness matrix is built for plane steel members with damage cumulation effects.

Shaking table tests of two shallow reticulated shells

Abstract In this paper, shaking table tests of two shallow reticulated shells under earthquake loading were described. Local and global dynamic instabilities were observed in the test and time–history curves for stresses of members and nodal displacements were given respectively. It was shown that there were sudden changes in these curves, which were regarded as the signs of local and global dynamic instability. Based on test results, the law of structural dynamic instability was summarized, the definition of dynamic instability and several practical criteria proposed by the authors were illuminated. Finally, some calculation results from theoretical analyses of the two models under static and dynamic loading were given. By comparison of them, it can be seen that there are many common properties that reflect the stability behaviors and can be used to determine the state of static and dynamic stability of structures.

Improvements on the arc-length-type method

Arc-length-type and energy-type methods are two main strategies used in structural nonlinear tracing analysis, but the former is widely used due to the explicitness and clarity in conception, as well as the convenience and reliability in calculation. It is very important to trace the complete load-deflection path in order to know comprehensively the characteristics of structures subjected to loads. Unfortunately, the nonlinear analysis techniques are only workable for tracing the limit-point-type equilibrium path. For the bifurcation-point-type path, most of them cannot secure a satisfactory result. In this paper, main arc-length-type methods are reviewed and compared, and the possible reasons of failures in tracing analysis are briefly discussed. Some improvements are proposed, a displacement perturbation method and a force perturbation method are presented for tracing the bifurcation-point-type paths. Finally, two examples are analyzed to verify the ideas, and some conclusions are drawn with respect to the arc-length-type methods.

Seismic analysis of steel structures considering damage cumulation

The research on the development of a reliable analytical model for seismic analysis of steel structures is presented. The non-linear damage cumulation hysteretic model incorporating the deterioration of stiffness, strength and strain hardening for structural steel is proposed and validated. The complete loading history, energy dissipation and the effect of the maximum plastic strain are taken into account in the model. The constants in the model are determined from regression analysis of experimental results of simple standard tensile and cyclic tests. Finite element formulations for beam and structural solid element considering the damage cumulation are derived. A computer program capable of calculating the hysteretic model of steel members, predicting the damage state and crack initiation, and carrying out non-linear time history seismic analysis of steel structures is developed. Solutions obtained from the model are in good agreement with experimental results. It was demonstrated that the damage cumulation effect is considerable and important in structural seismic analysis.

Experimental Study on the Spatial Roof Structure of 80,000-seat Stadium in Shanghai

Publisher Summary This chapter discusses the model of the spatial roof structure of the 80,000-seat stadium in Shanghai, made up of radial cantilevering main trusses and annular linking girders, and is tested under four different combinations of loads. A comprehensive investigation of static behavior of this saddle-shaped spatial truss structure is explained. Topics covered are: design of the structural model, structural behaviors under different load cases, computational model selection, comparison of the finite element method (FEM) predictions and the test results, and spatial work behaviors of this overall truss system. Based on both theoretical and experimental analysis, proposals on design and analysis of the real structure are put forward.

Discussion on structural scheme selection of super tall building

Publisher Summary The chapter discusses structural scheme selection of a super tall building. On structural scheme selection of a high-rise building, designers first advise several structural systems based on their experience after analyzing the proposed project. Then several specialists determine the optimal alternative. However, this method has some disadvantages of higher random, dependence on individual capacity, bigger work, uncertainty, and more difficulty to contrast. It primarily depends on comparing with existing buildings rather than depending on computing. Therefore, for structural scheme selection of a super tall building, this method will yield diverse general economic benefits. The chapter presents another way. At first, architects confer with designers and find several preliminary schemes satisfying project demands. Then, a multilevel structural model on structural scheme selection of a super tall building is proposed. The chapter also provides division of technical economic index into three parts: mechanic behavior index, seismic behavior index, and economic performance index.

Analysis of Nonlinear Behavior of Steel Frames under Local Fire Conditions

ABSTRACT A finite element approach is presented in this paper for analysis of nonlinear behaviour of steel frames under local fire conditions. The effects of geometric nonlinearity, temperature dependent material nonlinearity and variations in temperature distribution across sections of frame members are considered. Based on the principle of virtual work, the temperature - induced load vector and temperature - dependent geometric stiffness matrix are derived. Following the common procedure of finite element methods, a. computer program is developed for calculating either the ultimate load at a specified temperature or critical temperature at a specified load level. The effectiveness of the approach is verified by a good prediction on the behavior of a steel frame experienced fire experiment.