工程科学与技术2025，Vol.57Issue(6)：70-80,11.DOI:10.12454/j.jsuese.202400050
大变形加载下铅芯橡胶隔震支座滞回特性与隔震性能分析
Hysteretic Behavior and Seismic Isolation Analyses of Lead Rubber Bearings Under Large Cyclic Strain Loading
摘要
Abstract
Objective Lead rubber bearings(LRBs)tend to exhibit significant stiffening and degradation behavior when subjected to large shear strain defor-mation.However,these two phenomena,attributed to the Scragging and Mullins effects,are not thoroughly examined or adequately integrated into seismic isolation design procedures.The objective of this study is to comprehensively investigate the large-strain properties of LRBs.In addi-tion,a numerical comparison is presented to demonstrate variations in seismic response when different modeling techniques are applied during strong earthquake shaking.The findings of this study significantly contribute to developing a more precise design methodology for seismically isolated structures,particularly in regions with high seismic intensity. Methods Reversed cyclic tests were conducted on two different types of bearings.The dynamic compression-shear machine was employed for these tests.The reversed cycles were executed in a pseudo-static manner with an average velocity of 2 mm/s.A constant compression of 12 MPa was maintained throughout the test.The testing protocol consisted of four distinct loading sequences that covered both low-to-moderate and large strain loading amplitudes.The test sequences include equal amplitude,increasing amplitude,unsymmetric,and near-field loading scenarios,re-spectively.The maximum shear force in the first cycle was significantly greater than that of the subsequent cycles,primarily due to the Scragging effect.From the second to the eleventh cycles,the force gradually decreases,attributed to the temperature increase in the lead core.The maximum shear force decreases by 14.6%and 22.1%in total for LRB500 and LRB800,respectively.The variation in the equivalent damping ratio follows a similar trend.In addition,the results demonstrated that the traditional bilinear model adequately captures the hysteretic response of LRBs under design-level shear strain with satisfactory accuracy. Results and Discussions The experimental results for large shear strain deformation were compared.A significant stiffening effect occurred when the shear strain exceeded 200%.The secant stiffness after the stiffening stage was found to be 1.6 times and 1.4 times greater than the design-level stiffness for LRB500 and LRB800,respectively.The loading history influenced the stiffening behavior,where a 20.2%additional increase in shear force occurred under the same shear amplitude level.In addition,the experiment revealed the occurrence of degradation,primarily during the initial large strain loading cycle.The traditional model failed to accurately capture the hysteretic response of LRBs under large shear strain de-formation.A comprehensive evaluation of the seismic performance of an actual base-isolated building was conducted using the benchmark model of an isolated RC frame structure located in Luding,Sichuan Province.This building experienced significant shear failure in most of its isolators during the 2022 Luding earthquake.Regarding modeling techniques,a simplified multi-degree-of-freedom shear-type model was adopted to rep-resent the isolated superstructure,while the isolation layer was modeled in detail.Both the traditional Bouc-Wen(BW)model and the General-ized Bouc-Wen(GBW)model were utilized to represent the horizontal hysteretic behavior of LRBs to investigate the seismic response of the building,considering the large strain nonlinearities of LRBs.The GBW model was specifically developed to account for the large-strain behavior of LRBs,building upon the basic framework of the BW model.It is demonstrated that the hysteretic curves generated by the GBW model closely matched the test results.The analysis employed field-recorded seismic waves from both far-field and near-field sources.The time history and re-sponse spectrum were given.The peak input acceleration was 527 cm/s2,and a significant velocity pulse was observed in the near-field record.This study examined the differences in seismic response when using the BW and GBW models.A comparison was made for the shear deforma-tion and hysteretic curves of LRBs under far-field earthquakes.The results indicated that LRBs experienced moderate shear strain under far-field earthquakes;thus,the large strain nonlinearities were not significant.Therefore,the isolation displacement and hysteretic curves obtained using both models were similar.However,under near-field earthquakes,differences were observed.The maximum shear deformations calculated using the BW and GBW models were 428%and 363%,respectively.The significant hardening behavior observed during the first large strain cycle ef-fectively limited the maximum isolation displacement of the LRB-isolated building;however,it raised concerns regarding the potential amplifica-tion of peak shear forces.The result demonstrated that incorporating the large strain behavior of LRBs in the modeling led to increased story drift in the isolated superstructure. Conclusions This study provides comprehensive insights into the large-strain nonlinearities of LRBs through experimental investigations.In addi-tion,numerical simulations were performed to compare the dynamic seismic response of an isolated building while considering these large-strain nonlinearities.The results indicate that LRBs exhibit significant hardening and degradation behavior under considerable shear strain,which sig-nificantly influences the seismic response of both the isolation layer and the superstructure.These findings establish a foundation for developing a more accurate seismic isolation design methodology.Future research should further investigate the mechanical properties of seismic isolators un-der ultimate seismic conditions to enhance the seismic resilience of structures located in near-fault regions.关键词
隔震结构/铅芯橡胶隔震支座/大变形加载/支座硬化/强度退化Key words
seismically isolated structure/lead rubber bearing/large strain loading/bearing hardening/strength degradation分类
土木建筑引用本文复制引用
王斌,杨怡昭,陈鹏,张展宏,戴靠山,刘兢兢..大变形加载下铅芯橡胶隔震支座滞回特性与隔震性能分析[J].工程科学与技术,2025,57(6):70-80,11.基金项目
国家自然科学基金项目(52208318) （52208318）
四川省自然科学基金项目(23NSFSC1413) （23NSFSC1413）
