Evaluation of the seismic behavior of reinforced concrete structures with flat slab-column gravity frame and shear walls through nonlinear analysis methods

This paper presents an investigation of the seismic behavior of reinforced concrete(RC)structures in which shear walls are the main lateral load-resisting elements and the participation of flat slab floor systems is not considered in the seismic design procedure.In this regard,the behavior of six prototype structures(with different heights and plan layouts)is investigated through nonlinear static and time history analyses,implemented in the OpenSees platform.The results of the analyses are presented in terms of the behavior of the slab-column connections and their mode of failure at different loading stages.Moreover,the global response of the buildings is discussed in terms of some parameters,such as lateral overstrength due to the gravity flat slab-column frames.According to the nonlinear static analyses,in structures in which the slab-column connections were designed only for gravity loads,the slab-column connections exhibited a punching mode of failure even in the early stages of loading.However,the punching failure was eliminated in structures in which a minimum transverse reinforcement recommended in ACI 318(2019)was provided in the slabs at joint regions.Furthermore,despite neglecting the contribution of gravity flat slab-column frames in the lateral load resistance of the structures,a relatively significant overstrength was imposed on the structures by the gravity frames.

建筑工程框剪结构梁板柱高支模体系施工技术

高支模体系是一种通过使用支撑模架系统,对高、跨、承载力大的建筑体起到支撑作用的技术。本文以某市一框架剪力墙结构的商品住宅楼为研究对象,对施工过程中的梁板柱高支模体系施工技术进行研究,为高支模体系设计及操作人员提供参考价值。

Study of Suitability of Out-of-Codes Tall Slab-Column and Shearwall Structure

The purpose of this paper is to discuss the suitability of out-of-codes tall slab-column and shearwall structure and to popularize the structure in seismic region.In the research,flat-plate floor was used in slab-column and shearwall structure in the practical engineering,the key parameters of slab-column and shearwall structure and frame-shearwall structure such as deflection,punching shear behavior,story drift and capability curve were worked out by static plastic analysis,elastic-plastic time history analysis and pushover analysis,then the suitability of out-of-codes tall slab-column and shearwall structure was evaluated.The results show that the out-of-codes tall slab-column and shearwall structure studies could satisfy the require of deflection and punching shear behavior,the story drift under 7 degree expected rare earthquake waves could satisfy the limit value in the codes and the seismic design spectrum was crossed by the capability curve of the structure and the structure could not collapse.The conclusion is that slab-column and shearwall structure with reasonable design built in Ⅱ soil site of intensity 7 seismic fortification zone can be designed higher than the limit height in the codes.

Experimental study on the seismic performance of staggered slab-column joints

The low-cycle loading test of two staggered slab-column-boundary beam joints was carried out to study their seismic performance.The crack development,load-displacement relationship,displacement ductility,and energy dissipation performance of the staggered slab-column joints(SSCJ)were studied.Experimental results reveal that both specimens present short-column brittle shear failure.Furthermore,an obvious hysteretic curve pinching phenomenon occurred.Thus,it can be concluded that the seismic performance of the joints is insufficient.These results suggest that the anchorage of the longitudinal reinforcement of the slab in the joint’s core area should be improved,and attention should be paid to the short-column stirrup configuration of the SSCJ.These results can provide a research basis for the design of such joints in future applications.

Effects of edge beams on mechanic behavior under lateral load in reinforced concrete hollow slab-column structure

In order to get the formulae for calculating the equivalent frame width coefficient of reinforced concrete hollow slab-column structures with edge beam,the finite element structural program was used in the elastic analysis of reinforced concrete hollow slab-column structure with different dimensions to study internal relationship between effective beam width and the frame dimensions.In addition,the formulas for calculating the increasing coefficient of edge beam were also obtained.

Punching Shear Behavior of RC Slab-Column Connections with Nonrectangular Columns

This paper present an experimental study on the RC slab-column connections with nonrectangular columns, namely cross-shaped column, T-shaped column and L-shaped column. The punching shear deformation and strength characteristics of slab-column connections with nonrectangular columns under punching shear load are investigated. Nine specimens with the three kinds of nonrectangular columns and two reference specimens with square columns are tested. The tested ultimate loads, deformations, and failure modes of specimens are presented and discussed. Test results reveal that the punching shear strength and ductility of the connections with nonrectangular columns are higher than those of the corresponding connections with square columns, and also prove that the application of nonrectangular columns to flat-plate structure was feasible. Based on the test results, one method of calculating punching shear strength of connections with nonrectangular columns is proposed, which conforms with the current design practice of China. The test results on the punching shear strength are compared with the predictions of the formulas proposed by codes of several different countrie; and the predictions given by ACI code and China code are found to be conservative as the reinforcement ratio is increased.

高烈度区某旋转斜柱框架-核心筒超限高层结构设计要点分析

昆明某147.5m超高层建筑,共37层,其中12~35层外框架绕平面形心相对下层旋转,共旋转30°,采用钢管混凝土框架-钢筋混凝土核心筒混合结构体系。根据旋转斜柱的特点,结构设计采取了针对性的分析方法,制定相应的性能目标并提高了关键构件(框架柱、底部加强区剪力墙、楼板)的抗震性能。利用YJK、ETABS及SAUSAGE软件对结构进行了不同性能水准地震作用下结构承载力、变形及稳定性分析,重点验算旋转斜柱对结构整体性能、楼板、核心筒等构件的影响以及斜柱本身的抗震性能,并采取针对性抗震构造措施。另外,采用MIDAS FEA实体有限元分析了斜柱关键节点的可靠性。结果表明:结构在不同性能水准地震作用下的各项设计指标均满足相关规范要求;水平力形成的扭矩在各种工况下的传递路径均有效可靠,各构件可实现预期的抗震性能目标,结构设计方案是可行且安全的。

光峰科技总部大厦结构设计要点

以光峰科技总部大厦塔楼项目为工程背景,基于该项目存在高度超限、扭转不规则、楼板不连续、局部穿层柱等不规则项,属于超限高层建筑的情况。对结构进行了小震弹性、中震及大震弹塑性等计算分析,针对塔楼跨层柱进行了屈曲分析,保证跨层柱的稳定性;并对斜柱顶底楼盖、两处局部体型收进竖向构件楼板进行楼板应力补充分析。计算结果表明结构具有良好的抗侧刚度,较好地满足抗震设计预期的性能目标。

预应力混凝土无梁楼盖配筋形式新探讨

根据实际工程中力的传递路径简短的原则 ,通过对无梁楼盖配筋形式的分析比较 ,剖析传统配筋形式存在的问题 ,探讨更合理更经济的无梁楼盖的配筋形式 ,以节约钢材 ,使结构构件受力更合理 。

上海1933老场坊检测与评估

1933老场坊原先为上海工部局宰牲场,为上海市第4批优秀历史建筑,房屋平面布局外方内圆,主体结构为四层无梁楼盖结构。根据优秀历史建筑检测评估要求,对该房屋进行了包括建筑结构复核测绘、材料力学性能检测、完损状况检测、沉降变形检测等内容的现场检测,依据现场检测内容并结合计算分析结果综合评定了该历史建筑的结构安全性和整体抗震性能,提出了该房屋的特色保护内容,同时针对结构中存在的薄弱环节提出了相应的加固建议。

无梁楼盖结构计算方法的探讨

结合结构设计的工程实践，通过对无梁楼盖结构的分析比较，剖析现行设计计算中存在的问题，探讨解决的办法及适合现阶段无梁楼盖结构设计的实用计算方法的可行性，供结构设计者参考。

沿对角线配筋无梁楼盖受力性能试验研究

为了实现力的最直接传递,对2个沿对角线方向布置预应力筋的无梁楼盖分别进行了加载破坏试验,并对沿对角线布置预应力筋的无梁楼盖的荷载-挠度关系曲线、荷载-应变关系曲线、荷载-预应力筋张拉力增量关系曲线进行了研究.结果表明,沿对角线布置预应力筋的无梁楼盖具有良好的受力性能.

北京科技会展中心预应力板柱结构设计分析

介绍了北京科技会展中心工程预应力结构的设计方法 ,并对板柱结构特殊边界条件的处理提出了建议。预应力结构设计中结合预应力施工对预应力钢筋的布置原则进行了讨论 ,并提出了针对本工程的布置建议 ,有效地解决了预应力设计和施工中存在的若干问题。

无梁楼盖地震响应的试验研究与破坏机理分析

以某典型单层多跨无梁楼盖人防结构为研究对象,根据相似条件设计了场地土和结构模型,分别采用Elcentro波和Kobe波进行水平单向或双向耦合地震动输入,进行两种不同埋深情况下砂土地基中结构地震响应的振动台模型试验研究。给出了结构加速度、应变、位移等动力响应的量测结果,分析了无梁楼盖人防结构地震破坏机理。结果表明:双向耦合输入地震荷载比水平单向输入地震荷载引起的结构动力响应大;浅埋结构与深埋结构相比各种动力响应均明显增大;由于结构中柱相对独立,其动力反应较侧墙强烈;结构中柱上下端、侧墙上下角隅处都是容易遭受地震破坏的部位;竖向地震力对结构的动力响应产生明显影响,其破坏力不容忽视。

板柱结构体系与板柱节点研究的新进展

板柱结构是一种常用的结构形式,但由于自身抗侧刚度和抗侧承载力较小,节点易受到冲切破坏,尤其在地震作用下的不平衡弯矩会导致节点发生冲切破坏,甚至引起连续性倒塌。本文详细列举了板柱结构的震害实例,分析了主要的破坏原因;进一步介绍了国内外关于板柱结构的整体性能试验和节点抗震研究的新进展,阐述了目前常用的提高节点抗冲切能力措施,包括:配置抗冲切钢筋、提高板底纵筋强度和配筋率、应用钢纤维高强混凝土材料、设置柱帽或托板等,同时阐述了板柱结构在我国实际工程中的应用情况和标准化。最后,提出了板柱结构相关研究和推广应用中存在的问题。

均布荷载作用下板柱体系计算方法——板格法

对无梁楼盖采用单重三角级数及双重三角级数的公式,求得板内的弯矩分布。根据已知的边界条件以及板柱协调工作原理,建立无梁楼盖挠度函数和内力的弹性分析解,找出了零弯矩分布规律,提出了板、柱体系在竖向荷载作用下的简化实用的计算方法———板格法。这种方法设计合理,内力分布符合实际,改变了传统的跨中板带,柱上板带的划分计算无梁楼盖的方法,有利于实际工程的应用并对实际工程具有参考价值。

沿对角线布筋的无梁楼盖优越性能比较分析

将沿对角线布置预应力筋的无梁楼盖与传统配筋形式的无梁楼盖进行对比,在理论分析和试验数据上明确沿对角线布置预应力筋无梁楼盖的优越性,推广无梁楼盖的应用,并为进一步的理论分析奠定基础。

无梁楼盖简化公式及影响因素分析

根据已知的边界和受力条件,建立无梁楼盖挠度和内力的弹性分析解,并利用相对坐标引入参数,对此弹性解进行化简.对简化后的挠度和内力进行分析,找出影响无梁楼盖挠度和内力的因素,并通过改变这些影响因素,分析其对挠度和内力的影响作用.

装配整体式预应力板柱结构体系抗震性能评估与加固技术研究

介绍了我国20世纪80年代初期建造的装配整体式预应力板柱结构体系的受力特点,以北京市建筑设计研究院有限公司C座科研楼工程为例,对该结构体系的抗震性能进行了评估,根据问题研究了各种加固策略、技术措施,并进行了数值验证,构建了传统抗震加固手段与消能减震技术相结合的抗震加固方法。评估结果表明,20世纪80年代初期建造的装配整体式预应力板柱结构体系在使用40年后,存在整体刚度不足、耗能能力差、水平构件承载力不足、结构竖向安全性得到不保证的问题。针对上述问题,提出了4点加固策略:核心筒周圈剪力墙增设250mm厚钢筋混凝土加强层,柱头增设微型防屈曲支撑,暗梁粘钢补强,板柱连接节点增设钢牛腿。研究结果表明,上述加固措施能够有效提升该结构体系的抗震性能,满足后续使用年限30年的要求。

板柱体系模型动力试验研究

针对民防工程抗力加固问题,采用量纲分析和微分方程法推导和分析钢筋混凝土板柱体系模型动力试验的相似比并建立试验模型。开展板柱体系立柱加固模型的动力性能试验研究。了解在核爆炸冲击波载荷作用下无边墙、无柱帽板柱体系的动力性能、破坏形态和采用后加柱加固的实际效果等问题。研究表明,采用后加柱加固明显改变结构的破坏形态,较大提高整个结构尤其是结构顶板的承载能力;无柱帽板柱体系的节点抗冲切破坏问题是一个薄弱环节。