低周反复荷载下方钢管混凝土框架抗震性能的试验研究

通过对一榀两跨三层的方钢管混凝土组合框架在低周反复荷载作用下的模型试验，深入研究了方钢管混凝土组合框架的滞回性能、延性、耗能能力和刚度退化等抗震性能。研究结果表明：方钢管混凝土结构的抗震性能优于混凝土结构。     

组合梁-方钢管混凝土柱框架结构抗震性能的pushover分析

采用考虑组合梁多材料截面引起的正向、负向刚度、强度和承载力不同的截面本构模型,建立了组合梁结构的弹塑性分析模型,对一个15层的钢混凝土组合梁-方钢管混凝土柱框架结构开展了多遇地震、罕遇地震下的pushover分析,为组合框架结构体系的抗震性能分析以及pushover方法在该体系中的应用提供了参考。在此基础上,与钢梁-方钢管混凝土柱框架结构、钢梁-钢筋混凝土柱框架结构进行对比研究,比较了几种结构的动力特性,表明组合梁-方钢管混凝土柱框架结构体系相对于其它两种框架结构体系具有更好的抗震性能。     

基于性能的钢管混凝土空间简体结构抗震设计

钢管混凝土空间简体结构是将钢管混凝土柱通过环状桁架拉结形成中空筒状的高耸特种结构,在化肥厂的建造中得到了广泛的应用,但其抗震性能的研究目前仍属空白.以应用比较广泛的110m高,17m直径的典型造粒塔为工程背景,对此类结构进行了基于性能的抗震设计研究.采用三维弹塑性有限元模型对结构进行了罕遇地震作用下的动力弹塑性时程分析,同时用Push-over方法进行静力弹塑性分析,得到了罕遇地震作用下梁柱塑性区的主要分布.结果表明,楼梯间钢柱和环状桁架对其抗震性能影响较大,此类结构抗震性能一般较好.最后根据结果提出了相应的抗震设计对策,可为同类构筑物设计提供参考.     

基于实例分析的绿色钢结构抗震与环保性能研究

为优化绿色钢结构建筑的安全性能与环保性能,基于一40层框架-支撑钢结构建筑实例进行抗震性能与环保性能分析。根据实际建筑参数构建该绿色钢结构建筑剖面图,基于时程分析法记录不同地震波作用下建筑水平位移随时间变化情况,基于Pushover分析法分析方钢管混凝土组合异形柱在罕见地震中的基底剪力和弹塑性变形,基于对比实验方法验证其环保优越性,并得出以下结论：建筑的方钢管混凝土组合异形柱符合国家抗震性能要求,整体建筑的抗震性能随楼层的增加而减弱;与钢筋混凝土结构、砖混结构相比,钢结构能有效节约施工水电用量、降低施工噪声,是一种抗震性强、环保性能优的绿色建筑形式。     

钢管混凝土框架-混凝土核心筒减震结构振动台试验研究

某超高层钢管混凝土框架-混凝土核心筒结构因指标超限在设计中采用了耗能减震技术,为了检验该减震结构的抗震性能,制作了1/35的缩尺模型,通过在钢管混凝土框架设置阻尼器或不设置阻尼器,进行模拟地震振动台对比试验,研究了模型结构的动力特性和不同烈度地震作用下的加速度、位移和应变响应。研究结果表明:地震作用下,该钢管混凝土框架-混凝土核心筒减震结构与钢管混凝土框架-混凝土核心筒结构相比,位移、加速度和应变响应均有一定程度的降低;罕遇地震作用下,通过设置耗能减震构件,层间位移角最大值从超过规范要求的1/84减低至满足规范要求的1/130,表明该减震结构具有更优良的抗震性能。     

钢管混凝土重力柱—混凝土核心筒结构静力弹塑性分析

以钢管混凝土柱框架—混凝土核心筒结构为背景,将钢管混凝土柱、钢框架梁、核心筒之间的刚性连接改为螺栓铰接,形成钢管混凝土重力柱—混凝土核心筒结构.运用有限元软件Canny建立数字模型,对新型结构进行3种不同侧向加载模式的pushover分析,根据能力谱法求出7度大震作用下的性能点,并与动力时程分析结果对比,得出倒三角形加载模式精度更高.进一步研究结构塑性铰发展过程,指出结构中部区段为薄弱层,核心筒连梁和底部剪力墙为薄弱部位,应加强抗震构造.     

预制预应力混凝土装配整体式框架拟动力试验研究

通过一榀二跨二层预压装配式预应力混凝土框架拟动力试验,研究了预压装配式框架的破坏机制、变形性能、刚度退化及耗能能力等抗震性能,并对模型结构进行弹塑性动力分析。研究表明,预压装配式预应力结构有着很强的变形恢复能力,框架节点处于双向受压状态,节点刚度和核心区抗裂性得到增强,提高了框架整体抗侧刚度。在竖向和水平力的作用下,梁端在叠加的负弯矩作用下率先出现塑性铰,可实现"强柱弱梁"的设计要求,预压装配式预应力结构具有良好的抗震性能。     

基于能量原理的钢筋混凝土筒体结构抗震性能研究

本文通过能量法研究了钢筋混凝土筒体结构的抗震性能。文中采用振型分解法按等效单自由度体系求解筒体结构的滞回输入能;用pushover法分析了滞回耗能在结构层间的分布规律及结构自身的耗能能力;根据楼层滞回耗能与弹塑性层间位移的关系求出了薄弱层的弹塑性位移。对一高层钢筋混凝土框架-筒体结构在7度罕遇地震下的抗震性能进行了评估,通过与非线性动力时程分析的对比,证明了方法的可行性。     

直接基于位移设计的高强钢组合K形偏心支撑钢框架的抗震性能研究

K形高强钢组合偏心支撑(K-HSS-EBF)是指耗能连梁和支撑采用Q345钢,而框架梁、框架柱采用高强度钢(如Q460)。为研究其在罕遇地震作用下的抗震性能,在试验研究的基础上,采用直接基于位移的抗震设计方法设计了5层、8层和12层算例,分别进行静力推覆分析和动力弹塑性分析,研究高强钢组合偏心支撑钢框架在罕遇地震作用下层间侧移分布和破坏模式。研究结果表明:直接基于位移的抗震设计方法设计的算例在罕遇地震作用下,结构的层间侧移满足我国现行抗震规范的要求,结构呈理想的渐进式梁铰屈服机构,并证明该设计方法的合理性和可靠性。     

基于能量原理的钢筋混凝土简体结构抗震性能研究

本文通过能量法研究了钢筋混凝土简体结构的抗震性能。文中采用振型分解法按等效单自由度体系求解简体结构的滞回输入能；用pushover法分析了滞回耗能在结构层间的分布规律及结构自身的耗能能力；根据楼层滞回耗能与弹塑性层间位移的关系求出了薄弱层的弹塑性位移。对一高层钢筋混凝土框架-简体结构在7度罕遇地震下的抗震性能进行了评估，通过与非线性动力时程分析的对比，证明了方法的可行性。     

消能减震高层方钢管混凝土框架结构振动台试验研究和弹塑性时程分析

本文首先介绍了一幢安装了粘滞阻尼器的复杂体型高层方钢管混凝土框架结构的1/15缩尺模型的模拟地震振动台试验结果;在此基础上,建立了梁、柱构件的多弹簧模型并组建了整体结构的计算分析模型,运用此计算模型首先对试验模型结构进行了动力弹塑性时程分析,计算结果和试验结果吻合较好,验证了计算模型的正确性;最后,以同样方法对原型结构进行了计算分析,并结合试验结果研究探讨了此结构的抗震性能和阻尼器的消能减震效果。结果表明:该结构未出现明显的薄弱层,能够满足规范的抗震设防要求,阻尼器发挥了一定的消能减震效果,进一步提高了结构的抗震性能。     

套建增层预应力钢骨混凝土框架弹塑性地震反应分析

从套建增层改造实践中存在的问题出发,提出了一种新型外套增层结构型式,即以内置H型钢预应力混凝土组合梁为框架梁、以配置4个或8个角钢的角钢混凝土柱为框架柱的套建增层用框架结构,并给出了节点构造。根据不同的场地条件和地震设计分组,对基于现行设计标准设计的跨度为16m的新型套建增层框架进行了罕遇地震作用下的时程分析。分析结果表明,在满足常遇地震作用下的设计要求时,在7度和8度罕遇地震作用下,建造在I、II、III类场地上的部分套建增层框架将会倒塌。根据弹塑性反应分析结果,提出了在罕遇地震作用下避免这种套建增层框架发生倒塌的设计建议。     

Seismic retrofitting of reinforced concrete frame structures using GFRP-tube-confined-concrete composite braces

This paper presents a new type of structural bracing intended for seismic retrofitting use in framed structures. This special composite brace,termed glass-fiber-reinforced-polymer(GFRP)-tube-confined-concrete composite brace,is comprised of concrete confined by a GFRP tube and an inner steel core for energy dissipation.Together with a contribution from the GFRP-tube confined concrete,the composite brace shows a substantially increased stiffness to control story drift, which is often a preferred feature in seismic retrofitting.An analysis model is established and implemented in a general finite element analysis program-OpenSees,for simulating the load-displacement behavior of the composite brace.Using this model,a parametric study of the hysteretic behavior(energy dissipation,stiffness,ductility and strength)of the composite brace was conducted under static cyclic loading and it was found that the area ratio of steel core to concrete has the greatest influence among all the parameters considered.To demonstrate the application of the composite brace in seismic retrofitting, a three-story nonductile reinforced concrete(RC)frame structure was retrofitted with the composite braces.Pushover analysis and nonlinear time-history analyses of the retrofitted RC frame structure was performed by employing a suite of 20 strong ground motion earthquake records.The analysis results show that the composite braces can effectively reduce the peak seismic responses of the RC frame structure without significantly increasing the base shear demand.     

Behavior of ductile steel X-braced RC frames in seismic zones

A satisfactory ductile performance of moment-resisting reinforced concrete concentric braced frame structures (RC-MRCBFs) is not warranted by only following the provisions proposed in Mexico’s Federal District Code (MFDC-04). The nonlinear behavior of low to medium rise ductile RC-MRCBFs using steel X-bracing susceptible to buckling is evaluated in this study. The height of the studied structures ranges from 4 to 20 stories and they were located for design in the lake-bed zone of Mexico City. The design of RC-MRCBFs was carried out considering variable contribution of the two main lines of defense of the dual system (RC columns and steel braces). In order to observe the principal elements responsible for dissipating the earthquake input energy, yielding mappings for different load-steps were obtained using both nonlinear static and dynamic analyses. Some design parameters currently proposed in MFDC-04 as global ductility capacities, overstrength reduction factors and story drifts corresponding to different limit states were assessed as a function of both the considered shear strength and slenderness ratios for the studied RC-MRCBFs using pushover analyses. Additionally, envelopes of response maxima of dynamic parameters were obtained from the story and global hysteresis curves. Finally, a brief discussion regarding residual drifts, residual drift ratios, mappings of residual deformations in steel braces and residual rotations in RC beams and columns is presented. From the analysis of the obtained results, it is concluded that when a suitable design criterion is considered, good structural behavior of RC-MRCBFs with steel-X bracing can be obtained. It is also observed that the shear strength balance has an impact in the height-wise distribution of residual drifts, and an important “shake-down” effect is obtained for all cases. There is a need to improve design parameters currently proposed in MFDC to promote an adequate seismic performance of RC-MRCBFs.

     

Curvature ductility of columns and structural displacement ductility in RC frame structures subjected to ground motions

This paper examined the statistical relationship between the curvature ductility demands of columns and the global displacement ductility demands of reinforced concrete (RC) frame structures when subjected to earthquakes. Elements with a designated moment–curvature relationship were adopted for both beam and column elements, and five-story and ten-story RC frame numerical structures were established. Using pushover analysis and earthquake nonlinear dynamic time-history analysis, the maximum global displacement ductility demands of the structure and the maximum curvature ductility demands of the columns were determined. The effects of the spectral acceleration and the strong column factor on ductility demands were analyzed, and the quantitative relationship between the curvature ductility demands of columns and the global displacement ductility demands of frame structures were established. Moreover, the validity of the established relationship was further tested and verified through a real-world application. The results show that the maximum curvature ductility demands of the columns and the maximum displacement ductility demands of the structure were positively associated with the spectral acceleration and negatively associated with the strong column factor. A proposed first-degree linear relationship between curvature ductility of columns and structural displacement ductility in RC frame structures with two parameters was obtained by curve fitting, while considering the effect of the strong column factor. The model was highly correlated with the sampling analysis data. Applying the empirical model established in this study is a simple and effective means to guide the design of ductility and the assessment of RC frame columns.     

梁铰型屈服RC框架结构地震弹塑性位移增大系数研究

本文通过弹性和弹塑性时程分析,研究了水平地震作用下梁铰型屈服RC框架模型结构的楼层屈服剪力系数、基本自振周期、楼层数3个因素对弹塑性位移增大系数的影响,通过非线性回归分析给出了弹塑性层间位移增大系数经验公式;通过分析滞回耗能沿楼层高度的分布,初步确定了梁铰型屈服RC框架结构的薄弱楼层位置;基于结构损伤分析,讨论了抗震规范中RC框架结构弹塑性层间位移角限值的水准。     

基于纤维模型的空间网架支承体系的优化设计与分析

近年来,民用航空制造业的快速发展给大柱距空间网架结构带来新的契机。本文针对某大柱距厂房设计了无柱间支撑、柱间钢支撑和柱间消能支撑3种抗侧力结构体系。在此基础上,分别建立了3种结构体系的三维整体有限元模型,通过优化设计确立了钢支撑和消能支撑的具体设计参数,并进行了多遇地震作用下的弹性时程对比分析。最后,建立了结构弹塑性分析的纤维模型,对3种结构体系进行了罕遇地震作用下的弹塑性时程分析,对比研究了3种结构体系在大震作用下的倒塌机制。结果表明：采用纤维模型能够较为精确地进行结构的弹塑性时程分析;相较于不加柱间支撑结构体系,柱间钢支撑和柱间消能支撑结构体系在多遇地震作用下的结构层间位移分别衰减约32%和64%,在罕遇地震作用下的结构层间位移分别衰减约12%和46%,且均具有更好的倒塌机制。本文可供大柱距空间结构的设计与分析参考和借鉴。     

深圳市急救血液信息三中心公共卫生项目结构设计

针对深圳市急救血液信息三中心公共卫生项目存在扭转不规则、凹凸不规则、楼板不连续、尺寸突变及其他不规则超限项,对两侧塔楼各自独立抗震与两侧塔楼设置弱连接部位整体抗震进行包络,并对其进行多遇地震、设防地震及罕遇地震作用下抗震性能化设计。计算结果表明:对结构之间的弱连接部位采取楼板加宽、框架梁及框架柱设置型钢等抗震加强措施,构件可满足预定的性能目标要求,结构整体趋于稳定。