Seismic analysis of steel structures considering damage cumulation

Abstract

recognised fact that the stiffness, strength and energy dissipation capacity of structures deteriorate when subjected to cyclic loading. This deterioration is associated with the damage cumulating process in the material which already has micro-defects resulting from the construction and service period. The damage accumulated will inevitably affect the remaining strength or life of structures. Structural failure occurs when the damage has accumulated to a critical level. However, due to the complexity of the problem, there is no generally-accepted practical method in the structural analysis of steel structures that takes into account the damage cumulation effect. A reliable and practical damage cumulation model is thus required in the seismic analysis of new structures and residual-strength/life prediction for the maintenance or repair of present structures.Fracture mechanics has been successfully applied in predicting the failures of many engineering structures with existing macrocracks. However, the deterioration of stiffness and strength of metals occurs well before the initiation of a macrocrack due to the initiation of microcracks, intergranular debonding or decohesion between inclusions and the matrix [1]. This deterioration should be taken into account in a complete and reliable structural analysis. Continuum damage mechanics provides an efficient tool for the analysis of damage cumulation and has been successfully applied in pressure vessels and aeronautics engineering for creep, fatigue and ductile damage problems. Considerable efforts have been made for the application of damage mechanics in civil engineering structures, especially under seismic loading, which is a type of low-cycle fatigue loading.The deterioration of Young's modulus, yield strength and hardening coefficient in the hysteretic model of a material subjected to cyclic loading can be considered to have a relation with the damage variable (or damage index), a basic concept in damage mechanics. To quantify the damage in a material, an appropriate damage variable, which is able to describe the microstructural damaged state in terms of measurable mechanical parameters, is first to be defined. Theoretically, the value of the damage index should fall in the range of 0-1, where 0 corresponds to the undamaged state of the material and 1 the completely damaged state when failure Abstract 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...

Study on Hysteresis Model of Welding Material in Unstiffened Welded Joints of Steel Tubular Truss Structure

“…n semi-cycle, and the unloading process is approximately elastic. E D n is the elastic modulus with damage accumulation, which in respect of D n can be calculated by Equation (9) based on damage mechanics theory and Shen [30,31]. E 0 is the original elastic modulus, g and h are the damage parameters like η and ξ.…”

“…It is critical to find a constitutive model that can be used to describe the cyclic characteristics of welding materials. Shen [30,31] put forward a hysteresis model of steel, which has been considered as the damage accumulation of steel under cyclic loads. The model has good applicability but did not consider the effect of nonlinear hardening.…”

Analysis of Normalized Time‐frequency Response Spectra for Three Seismic Records

“…Although the peak acceleration of Mexico earthquake record (1962) was only 0.105g, for its long duration, the damage around the station was serious. After studying the development of a reliable analytical model for seismic analysis of steel structures, Shen and Wu (2007) concluded that the damage cumulation effect was considerable and important in structural seismic analysis. Analyzing a suite of seven structural models with strength and stiffness degrading characteristics by a suite of almost 500 strong-motion accelerograms, Bommer et al (2004) believed that seismic performance evaluation method for masonry structure should be improved and take duration into account.…”

WITHDRAWN: Evaluation HSE of a LSF system subject to near- and far-field earthquakes

“…Kratzig [29] proposed HSE indicators for providing estimates of seismic vulnerability by extending the structural damage concepts of aging structures to seismic design, where structures fail by passing the damage evolution over an ultimate bound. Shen and Shen [30] established a practical hysteresis model of steel members that takes the effects of damage accumulation and fracture into consideration and includes the calculation of the HSE index, the effects of HSE on the yielding point, the modulus of elasticity and hardening coefficient of steel, the stressestrain hysteresis relationship and the fracture criterion. Dimova and Negro estimated the structural vulnerability by fragility analysis incorporating the numerical models of the structural response in different seismic intensity levels into the experimental data [31].…”