考虑应变率效应的钢筋混凝土框架结构弹塑性地震反应分析

利用有限元软件ABAQUS对钢筋混凝土框架结构构件中混凝土应变率进行了分析,将梁、柱的弹塑性在应力-应变层次上进行模拟;研究了多维地震输入下应变率效应对钢筋混凝土框架结构弹塑性地震反应的影响以及同一地震波不同峰值加速度下钢筋混凝土弹塑性地震反应的应变率相关性,对比分析了考虑应变率与未考虑应变率下的弹塑性地震反应的差别。研究结果表明:框架柱的应变率明显大于框架梁,并且上部构件的应变率小于下部构件,构件跨中截面的应变率小于端部截面;考虑应变率效应时结构的位移反应、基底剪力和弯矩发生改变,峰值加速度较大的地震波作用下应变率效应更为显著,应变率效应对钢筋混凝土框架结构弹塑性地震反应存在一定的影响,尤其对强震下结构进行抗震分析时应适当予以考虑。     

单层偏心结构在水平地震动作用下的弹塑性分析

通过单层质量偏心体系钢筋混凝土框架结构,运用ANSYS软件,建立钢筋混凝土有限元空间实体整体式模型结构,输入罕遇地震波进行弹塑性时程分析。研究在单向水平地震作用下结构弹塑性侧扭耦合反应与混凝土结构从弹性、开裂、屈服直至结构的全部反应。     

框架-剪力墙结构静力弹塑性简化分析模型探讨

在对钢筋混凝土框架-剪力墙结构中剪力墙简化模型-等代框架模型分析的基础上,探讨了该模型在钢筋混凝土框架-剪力墙结构静力弹塑性计算中的应用,并进行了单片墙元与等代模型的弹塑性分析的对比,阐明了应用简化模型对框架-剪力墙结构进行罕遇地震作用下弹塑性分析的可行性。     

钢筋混凝土压弯构件考虑阻尼耗能时的地震破坏模型研究

本文分析了钢筋混凝土结构在弹塑性地震反应过程中阻尼耗能的分布和特点。对国内外现有的几种结构地震破坏模型进行了深入的分析比较研究。在分析各种破坏模型优缺点的基础上,针对钢筋混凝土压弯构件提出了考虑了阻尼耗能影响时的地震破坏模型。     

浅议钢筋混凝土框架结构抗震延性设计要求

在我国现在的多高层建筑中,钢筋混凝土框架结构是最常用的结构形式。结构抗震的本质就是延性,提高延性可以增加结构抗震潜力,增强结构抗倒塌能力。为了利用结构的弹塑性变形能力耗散地震能量,减轻地震作用下结构的反应,应将钢筋混凝土框架结构设计成延性框架结构。文章主要阐述了钢筋混凝土框架结构的抗震延性设计要求。     

近场地震下带楼梯框架结构弹塑性分析

为了研究近场地震作用下楼梯对钢筋混凝土框架结构的动力弹塑性影响,选取设防烈度为8度0.2g某地区钢筋混凝土框架结构,采用附加系数法设定6组模型,选用集集地震中2组近场地震波和2组远场地震波作为输入,应用Matlab2010对模型进行动力弹塑性时程分析。对比了近场和远场地震作用下不同模型的顶层位移和层间转角的变化情况,研究了近场地震对于不同模型弹塑性变形的影响。结果表明:与远场地震相比,近场地震对结构顶层位移和层间转角的影响更明显,随着楼梯对结构刚度影响增大,结构的顶层位移和层间转角最大值降低;当罕遇地震时,近场地震作用下结构产生的层间转角更大,损伤更加明显。     

钢筋混凝土巨型框架多功能减振结构体系

钢筋混凝土巨型框架多功能减振结构体系具有调频质量减振，基础隔震和阻尼耗能减振等多种减振功能。弹塑性动力分析和振动台试验表明，在水平地震作用下，钢筋混凝土巨型框架多功能减振结构体系的地震反应显著降低。     

高耸结构静力弹塑性分析研究

以改建的钢筋混凝土高耸结构--原南市发电厂烟囱作为研究对象,以上海2010年世博会观光塔这一典型的钢筋混凝土筒体结构作为背景工程,通过采用Pushover分析方法对其进行了全面地震作用下的静力弹塑性分析,计算结构在不同地震作用下的地震效应,研究结构在相应地震作用下的抗震性能,并分析结构在加固前后抗震性能指标的变化,明确...     

某超高层钢筋混凝土结构的抗震设计分析

以某超高层钢筋混凝土双塔楼结构为例,分别进行弹性地震和弹塑性地震的分析计算,在计算和分析的过程当中,考虑结构底盘刚度和塔楼之间相互作用的影响,对结构在地震作用下的安全可靠性能进行分析.     

钢筋混凝土异型柱结构振动台试验研究

分别输入不同加速度峰值的EL CENTRO波、上海人工波和南海波 ,对 15层 1∶7缩尺的钢筋混凝土异型柱结构模型进行了模拟地震振动台试验研究。通过试验现象分析、模型试验地震反应研究和结构弹塑性地震反应分析 ,得出有关钢筋混凝土异型柱结构抗震性能的若干结论     

钢支撑-混凝土框架动力非弹性扭转机理与抗扭设计研究

通过钢支撑-混凝土框架振动台试验研究了钢支撑失稳或其他构件损伤后引起的扭转突然增大问题,即非弹性扭转问题,结果表明钢支撑受压失稳或失效是导致此类结构出现非弹性扭转的重要原因。基于试验结果,分析了钢支撑失稳或失效导致结构非弹性扭转突增的机理;同时建立了设有偶然偏心的有限元模型算例并进行非线性分析,验证了在增加构件数量的条件下该类结构仍存在非弹性扭转突增问题,表明即使是对称结构,在普通钢支撑发生受压失稳及其反向受拉过程中,也会产生非弹性扭转及其突然增大现象。试验和案例分析均表明类似的现象,即在相同加载及偏心条件下纯混凝土框架非弹性扭转虽然存在,但其突然增大值比钢支撑框架结构要小;设置防屈曲支撑抗扭效果显著,优于设置钢支撑的混凝土框架和纯混凝土框架。建议工程设计中设置防屈曲支撑,可有效减控混凝土框架非弹性扭转危害;通过设置质量偏心,对钢支撑-混凝土框架结构进行强震下非弹性扭转响应分析,并在设计上对其最大值加以限制。     

Dynamic analysis of reinforced concrete frame-wall structures

The nonlinear response and failure mechanism of reinforced concrete frame-wall systems is investigated through the employment of a mathematical model. The mathematical model is composed of two mechanical models: a concentrated spring model used for the flexural behaviour of beam and column type members and a multiple spring model used for the response of the wall system. Both account for inelastic behaviour of reinforced concrete.The mathematical model is applied to a ten-storey frame-wall system. The constituent members are replaced by one of the mechanical models whose stiffness characteristics reflect the inelastic properties and hysteresis tendencies of the member. The resulting equations are solved by a step by step time integration procedure. Computed results are compared with experimental results obtained from a structure tested on the Illinois earthquake simulator. The correlated results are then used to define the significant response characteristics.     

Design of reinforced concrete frames with damage control

A reinforced concrete frame design methodology to control damage indices in structural elements and keep them within tolerable limits is presented. The structural element strengths are determined to satisfy the basic design goal, which requires elastic behavior during moderate earthquakes and inelastic behavior with tolerable damage during strong earthquakes. Maximum lateral displacement and plastic dissipated energy are used as design parameters. The method uses several inelastic static analyses to optimize the strength of the structural elements in order to satisfy the adopted damage indices. The proposed method was applied to a six-floor framed structure, representative of an actual building, and the expected solution was achieved after two optimization cycles. The structure designed with the proposed method was subjected to eight earthquake acceleration records. Its response was determined from inelastic dynamic analysis. The resulting damage indices were similar to those assumed in the design, which confirm the accuracy of the proposed method.     

Nonlinear seismic response of reinforced‐concrete free‐standing towers with application to TV towers on flexible foundations

Reinforced‐concrete (R/C) free‐standing towers such as TV towers are often analysed using elastic analyses as fixed‐base cantilever beams, ignoring the effect of soil–structure interaction. To take the capacity of structures after yielding into account, most designers usually prefer to decrease the peak values of the elastic response spectrum for the maximum credible earthquake (MCE) anticipated at the site by a factor called the ductility capacity factor, which varies with the design earthquake level and the structural characteristics of the structure neglecting the effect of supporting soil. To investigate the effect of foundation flexibility on the response of R/C free‐standing towers deforming into their inelastic range during intense ground shaking, a linear sway‐rocking model is applied in numerical modelling of the soil–structure system. The effect of concrete cracking and reinforcement yielding on the elements used in the structure modelling is taken into account by introducing a nonlinear model for R/C frame elements using the moment–curvature (M–?) relation. A method called pseudo‐dynamic analysis is presented to quantify the inelastic seismic response spectrum of a soil–R/C free‐standing system using response spectrum analysis method and push‐over analysis technique. The earthquake responses of cracked and uncracked systems for a practical TV tower and a practical range of soil shear wave velocity are calculated and compared with the objective of understanding how soil–structure interaction influences structural responses. Copyright © 2002 John Wiley & Sons, Ltd.     

地震中受损钢筋混凝土建筑弹塑性时程分析与振动台试验研究

对1985年墨西哥城大地震中受损的一幢10层钢筋混凝土框架-剪力墙结构楼房建立起空间三维杆系分析模型,并在弹塑性滞回模型中考虑了钢筋混凝土构件的退化特性,输入结构原型附近场地实际加速度记录进行三维时程分析,通过与1/10比例钢筋混凝土整体模型的三维振动台试验数据进行对比,验证了采用的弹塑性时程分析工具和振动台试验技术的有效性,讨论了其中需要进一步研究解决的问题。     

框架——剪力墙结构的静力弹塑性分析研究

静力弹塑性方法作为一种评价结构抗震性能和计算结构弹塑性变形的简化方法,近年来得到了广泛应用。但由于传统的定侧力模式的静力弹塑性方法只考虑第一振型,无法反映高层建筑结构的高阶振型影响。为考虑高阶振型的影响,Chopra在振型分解反应谱组合法的基础上,提出了MPA方法。本文首先讨论了应用MPA方法需注意的问题,然后用一个18层钢筋混凝土框架—剪力墙结构为算例,以逐步增量弹塑性时程分析结果为基准,对传统定侧力模式静力弹塑性方法和MPA方法的分析结果进行了对比研究。结果表明,相比于定侧力模式静力弹塑性分析结果,MPA方法的分析结果更接近弹塑性时程分析结果。     

装配整体式剪力墙模型结构振动台试验研究

为了研究装配整体式剪力墙结构的抗震性能,设计并制作了1个12层1/5装配整体式剪力墙模型结构,选用3条地震波,通过振动台试验,研究了装配整体式剪力墙模型结构的动力特性、加速度放大系数、楼层剪力和位移及最大层间位移角等动力响应,并记录了裂缝形态。试验分析表明：模型结构的自振频率在完成第一阶段水准地震波输入后下降约20%;随峰值加速度增大,模型结构自振频率减小,加速度放大系数逐渐降低,楼层剪力逐渐增大;在塑性阶段,预制墙板顶部或底部与现浇楼板连接部位出现多条水平裂缝,且沿模型高度分布较为均匀,模型结构的非线性变形明显,层间位移角显著增大,自振频率显著降低;采用层间位移角对其进行抗震性能评价,在8度抗震设防时该结构具有良好的抗震性能,但应加强预制墙板与楼板的连接,增强其整体性,避免楼层通缝的出现。     

Finite element modelling and field validation of prestressed concrete sleepers and fastening systems

Prestressed concrete sleepers and elastic fastening systems have been widely applied in North America to accommodate increased freight axle loading and the development of high-speed passenger rail systems. However, the design standard of the American Railway Engineering and Maintenance-of-Way Association remains unclear about the relationship between some critical design parameters and the vertical and lateral load paths through the track structure. In this study, field experimentation is conducted at the Transportation Technology Center in Pueblo, CO, and the test data are compared with finite element (FE) models of the track structure for model validation. Strain gauges and potentiometers are installed in the field to measure the response of concrete sleepers and fastening systems. The FE models consist of two parts: a detailed single-sleeper model to capture the local response of the loaded rail seat, and a global multi-sleeper model to provide realistic boundary conditions for the detailed model. The bond–slip behaviour between concrete and prestressing wires, and inelastic material properties are incorporated in the FE models. Good agreement is observed between the test measurement and the model output. The validated FE model is used for parametric studies on the some critical design parameters, and conclusions about the load path through the sleepers and fastening systems are summarised.     

Dynamic amplification factor for progressive collapse resistance analysis of an RC building

Linear static (LS), nonlinear static (NS) and nonlinear dynamic analyses were conducted to estimate the progressive collapse resistance of a reinforced concrete building. The step‐by‐step procedure recommended by the US General Service Administration was used for the LS analysis. Load‐displacement response curves were compared to investigate the force‐based dynamic amplification factor (DAF), which was defined in this study. It was observed that a constant DAF equal to 2·0 was conservative for estimating the collapse resistance of a ductile column‐removed building. However, the LS procedure may fail to appropriately simulate the inelastic response of the building. A capacity curve, constructed from the NS load‐displacement response, may be applied to prediction of the collapse resistance and DAF for a column‐removed building. An analytical method was proposed to demonstrate the dependency of the DAF on hinge model parameters. The proposed method was capable of predicting the collapse resistance and the force‐based DAF of an inelastic structure under vertical downward loadings. Copyright © 2008 John Wiley & Sons, Ltd.