素混凝土桩在侯马高层住宅小区中的应用

在考虑工程地质条件和投资费用的前提下,介绍了素混凝土桩复合地基在侯马高层中的设计、施工工艺及处理效果,从而论证了素混凝土桩在侯马地区高层建筑地基处理中的可行性和实用性。     

罕遇地震作用下的框架-摇摆刚架结构体系动力可靠度研究

针对钢筋混凝土框架结构的受力特点,采用增设摇摆刚架的抗震设计方法,以提高罕遇地震下建筑结构的安全性。建立了框架一摇摆刚架结构体系的计算模型,结合状态空间法与虚拟激励法,求解结构的平稳随机响应,并根据计算所得随机响应对框架一摇摆刚架体系的动力可靠度进行分析。以西部地区某已建成的6层框架结构为算例,探讨了罕遇地震作用下不同刚度比的摇摆刚架对新结构体系动力可靠度的影响。结果表明,通过增设不同刚度比的摇摆刚架,可以有效协调结构体系的变形模式,充分发挥结构的耗能能力,降低整体结构的条件失效概率。     

Impact of lateral force-resisting system and design/construction practices on seismic performance and cost of tall buildings in Dubai, UAE

The local design and construction practices in the United Arab Emirates(UAE),together with Dubai’s unique rate of development,warrant special attention to the selection of Lateral Force-Resisting Systems(LFRS).This research proposes four different feasible solutions for the selection of the LFRS for tall buildings and quantifies the impact of these selections on seismic performance and cost.The systems considered are: Steel Special Moment-Resisting Frame(SMRF),Concrete SMRF,Steel Dual System(SMRF with Special Steel Plates Shear Wall,SPSW),and Concrete Dual System(SMRF with Special Concrete Shear Wall,SCSW).The LFRS selection is driven by seismic setup as well as the adopted design and construction practices in Dubai.It is found that the concrete design alternatives are consistently less expensive than their steel counterparts.The steel dual system is expected to have the least damage based on its relatively lesser interstory drifts.However,this preferred performance comes at a higher initial construction cost.Conversely,the steel SMRF system is expected to have the most damage and associated repair cost due to its excessive flexibility.The two concrete alternatives are expected to have relatively moderate damage and repair costs in addition to their lesser initial construction cost.     

Study of the seismic response of a recycled aggregate concrete frame structure

Based on six-degree-of-freedom three-dimensional shaking table tests, the seismic response of a recycled aggregate concrete （RAC） frame was obtained. The analysis results indicate that the maximum story shear force and overturning moment reduce proportionally along the height of the model under the same earthquake wave. The story shear force, base shear coefficient and overturning moment of the structure increase progressively as the acceleration amplitude increases. The base shear coefficient is primarily controlled by the peak ground acceleration （PGA）. The relationships between the PGA and the shear coefficient as well as between the PGA and the dynamic amplification factor are obtained by mathematical fitting. The dynamic amplification factor decreases rapidly at the elastic-plastic stage, but decreases slowly with the development of the elastic-plasticity stage. The results show that the RAC frame structure has reasonable deformability when compared with natural aggregate concrete frame structures. The maximum inter-story drift ratios of the RAC frame model under frequent and rare intensity 8 test phases are 1/266 and 1/29, respectively, which are larger than the allowable value of 1/500 and 1/50 according to Chinese seismic design requirements. Nevertheless, the RAC frame structure does not collapse under base excitations with PGAs from 0.066 g up to 1.170 g.     

A study on the seismic performance of steel‐reinforced concrete frame‐concrete core wall high‐rise mixed structure by large‐scale shaking table tests and numerical simulations

This paper reports a study for the seismic performance of one large‐scaled (1/15) model of 30‐story steel‐reinforced concrete frame‐concrete core wall mixed structure. The study was implemented by both shaking table tests, in which the similarity ratio for lateral and gravitational accelerations was kept to 1:1, and numerical nonlinear dynamic analysis. The test observations presented herein include story displacement, interstory drift, natural vibration periods, and final failure mode. The numerical analysis was performed to simulate the shaking table test procedure, and the numerically obtained responses were verified by the test results. On the basis of the numerical results, the progressions of structural stiffness, base shear, and overturning moment were investigated, and the distributions of base shear and overturning moment between frame and core wall were also discussed. The test demonstrates the seismic performance of the steel‐reinforced concrete frame‐core wall mixed structure and reveals the potential overturning failure mode for high rise structures. The nonlinear analysis results indicate that the peripheral frames could take more shear forces after core wall damaged under severe earthquakes. Copyright © 2013 John Wiley & Sons, Ltd.     

农村住宅砌体结构地震破坏数值模拟研究

国内震害调查表明我国农村房屋在地震中破坏严重,主要原因是农村自建房屋大都缺乏基本抗震措施.近年来有关部门针对农村房屋的抗震性能提出一些改进措施,但这些措施实际抗震效果如何,除了极少数通过模型试验验证外,很少得到验证.本文建立了砌体结构非线性有限元分析模型,以一幢农宅为研究对象,通过地震时程反应来再现其在地震作用下的破坏状况.研究表明本文提出数值模型能够较好的模拟砌体结构在地震中破坏过程,发现结构抗震薄弱部位.通过对三种模型对比分析表明圈梁和构造柱可以有效提高砌体结构整体抗震性能,但对局部破坏影响不大,需要在以后抗震设计中加以考虑.     

锈蚀钢筋混凝土压弯构件恢复力模型研究

根据目前已有试验资料和理论分析,结合钢筋锈蚀引起结构破坏形态的改变,综合考虑结构各种耐久性损伤因素,并对箍筋锈蚀进行修正,提出了锈蚀钢筋混凝土压弯构件基于地震损伤的恢复力模型的确定方法.通过与现有试验进行对比分析,表明模型描绘的骨架曲线与试验结果总体吻合较好,模型计算的滞回曲线所描述的现象与试验一致,该恢复力模型可在损伤钢筋混凝土结构地震反应分析中采用.     

混凝土膨胀剂使用中存在的问题及解决措施

混凝土膨胀剂具有补偿混凝土干燥收缩的效果,但在地下室防水混凝土工程中,使用效果不理想,存在掺加膨胀剂后地下室底板和外墙出现混凝土开裂渗漏的现象。本文从设计源头,力求全面地、准确有效地提出解决措施。     

碳纤维布加固钢筋混凝土梁的现场实荷加载试验

通过对某工程中的钢筋混凝土梁采取粘贴碳纤维布的方式进行加固,并现场抽取试验梁进行了现场堆载实荷加载试验,对试验梁的挠度、裂缝开展情况和承载能力进行了全面分析,对该加固工程的效果进行了评价,供同行参考。     

静压管桩折断接桩补强加固技术

当前静压桩做为基础处理的常规手段得到普遍应用,但在施工中产生的各种影响桩身质量的缺陷处理方法却没有统一的规定,探讨和研究静压桩的缺陷补强方法是静压桩施工中的重要课题。介绍了静压桩受横向力折断后采用桩管内灌注钢筋混凝土桩心补强加固处理的成功案例,为静压桩的缺陷处理提供了参考。