Research On Mechanical Behavior And Theoretical Model Of Low-yield-point Steel Shear Panel Dampers

The mechanical behavior of the low-yield-point steel shear panel damper(LSSPD)is complicated when subjected to the cyclic loading,which have significant influences on the seismic performance of the high-rise frame structural systems.This dissertation focuses on the shear panel damper device made of BLY160 low-yield-point steel,with its mechanism,numerical model and application in the energy dissipation structure system being discussed in details.The main results of the research work are as follows:(1)The uniaxial stress-strain constitutive relationship of the low yield point steel BLY160 is investigated through a set of coupon tests,which are subjected to different loading paths including the monotonic tension and cyclic loading.The characteristics of BLY160 steel are calibrated,such as the low yield strength,high ratio of tensile strength to yield point and high elongation.The significant cyclic hardening and softening behavior with the strain range dependent effect is intensively compared and discussed.(2)The elasto-plastic constitutive model for the low yield point steel BLY160 is developed.Based on the kinematic-isotropic combined hardening theory,the modified model is proposed with the introduction of an additional internal variable standing the “transformation zone” and logistic function presenting the “S” shaped curve.Thus,the cyclic hardening and softening behavior and their multi-stage evolution process observed in test can be elaborately described.In addition,the developed constitutive model is implemented in the general FE software MSC.MARC,and is applied to the refined nonlinear analysis for various material,member and connection of steel structures.(3)The pseudo-static tests with reversed loading protocol are conducted to four groups of full-scale LSSPD specimens.The experimental results of test subassemblies,such as the hysteretic load-displacement relationship,deformation behavior,failure modes and energy dissipation capacity are discussed,and the influences of the width-thickness ratio and corner perforation of the panel,the stiffening rib size and the cyclic load history are analysed.The favorable seismic performance of this new type of steel shear panel damper device is demonstrated.(4)The different numerical models are developed for the LSSPD by improving the modelling technique in material and component levels,which are based on the refined shell element and macroscopic spring element,respectively.The hysteretic behavior is accurately simulated and work mechanical are precisely analysed.By leveraging the secondary development of the FE software MSC.MARC,an efficient tool representing energy dissipation devices are developed for analysis of structure system.(5)The nonlinear spring element is integrated into the computing platform COMPONA-MARC,and the modeling tool for the composite frame structures equipped with the energy dissipation device are developed.The numerical model is applied to the elastic-plastic history analysis of a three-bay ten story example frame system,the seismic behaviors including the nature vibration characteristics,the displacement responses and the plastic damage state and failure mode are simulated and evaluated.Therefore,the accuracy,efficiency and practicability of the developed model are further validated.