Progressive collapse resisting capacity of reinforced concrete load bearing wall structures

Reinforced concrete(RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthquakes, but also more economical. The effect of progressive collapse caused by removal of load bearing elements, in various positions in plan and stories of the RC load bearing wall system was evaluated by nonlinear dynamic and static analyses. For this purpose, three-dimensional model of 10-story structure was selected. The analysis results indicated stability, strength and stiffness of the RC load-bearing wall system against progressive collapse. It was observed that the most critical condition for removal of load bearing walls was the instantaneous removal of the surrounding walls located at the corners of the building where the sections of the load bearing elements were changed. In this case, the maximum vertical displacement was limited to 6.3 mm and the structure failed after applying the load of 10 times the axial load bored by removed elements. Comparison between the results of the nonlinear dynamic and static analyses demonstrated that the "load factor" parameter was a reasonable criterion to evaluate the progressive collapse potential of the structure.

Analysis on Construction Quality Control Technology of Reinforced Concrete Shear Wall Structure

In the process of continuous development of construction enterprises, new requirements have been put forward for construction projects. By strengthening the construction quality control of reinforced concrete shear wall structure, the construction level of reinforced concrete can be continuously improved, the construction quality can be guaranteed, and the construction project can be successfully completed, which is worthy of extensive application and promotion in construction enterprises, thus providing a broader development space for construction enterprises.

Numerical Analysis of the Structure of High-Strength Double-Layer Steel Plate Concrete Shaft by Drilling Method of Water-Bearing Weak Rock Formation

In order to ensure the safety of coal mine shaft construction, a double-layer steel plate concrete composite shaft wall structure was proposed. However, fewer studies were conducted on this structure, which made engineers too confused to fully recognize its feasibility of this structure. Hence, based on the previous experimental research on the Taohutu mine construction project in Ordos in Inner Mongolia, this research paper aims to provide a widely deep numerical analysis by the usage of the finite element software, in fact, to establish the corresponding numerical analysis model and make a comparison with the experimental data to get the rationality of the verified model. The influence of the composite characteristics of the steel plate and concrete on the ultimate bearing capacity and stress field of the shaft wall structure is studied here through the method of multi-factor analysis. Also, the optimal design scheme of the double-layer steel plate and concrete composite shaft wall structure is proposed in this research paper.

Numerical Modeling Strategy for the Simulation of Nonlinear Response of Slender Reinforced Concrete Structural Walls

A three-dimensional nonlinear modeling strategy for simulating the seismic response of slender reinforced concrete structural walls with different cross-sectional shapes is presented in this paper.A combination of nonlinear multi-layer shell elements and displacement-based beam-column elements are used to model the unconfined and confined parts of the walls,respectively.A uniaxial material model for reinforcing steel bars that includes buckling and low-cyclic fatigue effects is used to model the longitudinal steel bars within the structural walls.The material model parameters related to the buckling length are defined based on an analytical expression for reinforcing steel bars embedded in reinforced concrete elements,which are developed based on beam-on-springs model,and validated with experimental tests of boundary elements of structural walls available in the literature.Six experimental case studies of reinforced concrete walls with rectangularshape,T-shape,and U-shape cross-section are used to validate the structural wall numerical modeling strategy.

Double linear strain distribution assumption of RC beam strengthened with external-bonded or near-surface mounted fiber reinforced plastic

Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain coordination results of 34 reinforced concrete beams(four groups)strengthened with different methods were presented including external-bonded or near-surface mounted glass or carbon FRP or helical rib bar in order to study the strain coordination of the strengthening materials and steel rebar of RC beam.Because there is relative slipping between concrete and strengthening materials(SM),the strain of SM and steel rebar of RC beam satisfies the double linear strain distribution assumption,that is,the strain of longitudinal fiber parallel to the neutral axis of plated beam within the scope of effective height(h0)of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of SM and steel rebar satisfies the equation εGCH=βεsteel,where the value of β is equal to 1.1-1.3 according to the test results.

Function-Integrative Textile Reinforced Concrete Shells

This paper presents the development and technological implementation of textile reinforced concrete (TRC) shells with integrated functions, such as illumination and light control. In that regard the establishment of material, structural and technological foundations along the entire value chain are of central importance: From the light-weight design idea to the demonstrator and reference object, to the technological implementation for the transfer of the research results into practice. The development of the material included the requirement-oriented composition of a high-strength fine grained concrete with an integrated textile reinforcement, such as carbon knitted fabrics. Innovations in formwork solutions provide new possibilities for concrete constructions. So, a bionic optimized shape of the pavilion was developed, realized by four connected TRC-lightweight-shells. The thin-walled TRC-shells were manufactured with a formwork made of glass-fibre reinforced polymer (GFRP). An advantage of the GFRP-formwork is the freedom of design concerning the formwork shape. Moreover, an excellent concrete quality can be achieved, while the production of the precast concrete components is simple and efficient simultaneously. After the production the new TRC-shells were installed and assembled on the campus of TU-Chemnitz. A special feature of the research pavilions are the LED light strips integrated in the shell elements, providing homogeneous illumination.

High-Rise Residential Reinforced Concrete Building Optimisation

In the last few decades structure optimisation has become a main task in a civil engineering project. As a matter of fact, due to the complexity and particularity of every structure, the great amount of variables and design criteria to considerate and many other factors, a general optimisation’s method is not simple to formulate. As a result, this paper focuses on how to provide a successful optimisation method for a particular building type, high-rise reinforced concrete buildings. The optimization method is based on decomposition of the main structure into substructures: floor system, vertical load resisting system, lateral load resisting system and foundation system;then each of the subsystems using the design criteria established at the building codes is improved. Due to the effect of the superstructure optimisation on the foundation system, vertical and lateral load resisting system is the last to be considered after the improvement of floor. Finally, as a case example, using the method explained in the paper, a 30-story-high high-rise residential building complex is analysed and optimised, achieving good results in terms of structural behaviour and diminishing the overall cost of the structure.

蒙陕矿区内钢板-钢筋混凝土钻井井壁非均匀受力特性研究

以蒙陕矿区某煤矿风井为工程背景,利用双向不等压模型推导出水平地应力下井壁的受力形式,并得出了非均匀系数k的计算公式,确定了蒙陕矿区地层的不均匀系数范围为0.06~0.20,研判了钻井井壁全深受力关键横断面的受力破坏特征。根据有限元软件ANSYS模拟非均匀荷载条件下的井壁受力规律,井壁混凝土外缘环向应力为控制应力,井壁应力呈现非均匀分布,90°位置的不均匀程度大于0°位置,外荷载较小的90°位置受拉,而外荷载较大的0°位置受压。通过对井壁压力试验台对内钢板-钢筋混凝土进行非均匀加载试验分析,非均匀荷载对钻井井壁受力影响极为明显,在k=0.15时模型的峰值应力仅为均匀荷载条件下的23.1%~33.3%;在k=0.20时模型的峰值应力为均匀荷载条件下的20%左右,且破坏形式为混凝土先受拉破坏,随后钢筋和钢板屈服。研究结果表明,内钢板-钢筋混凝土钻井井壁对非均匀荷载较为敏感,在蒙陕矿区使用钻井法应该考虑非均匀系数的影响,且需要在井壁设计阶段重点关注井壁外荷载较小位置的受力。

济南华润万象城抗震性能分析与设计

济南华润万象城为一栋结构高度412m的超限高层商业建筑,采用框架-剪力墙结构。结构中同时存在扭转不规则、平面开洞、大跨度结构、大悬挑结构、斜柱、桁架悬挑等多项平面及竖向不规则情况。采用多种计算程序进行了抗震性能分析,其结果均满足既定的抗震性能目标。对复杂商业中的各关键部位设计进行了多方案比选,确定了合理的结构布置和适当的构造措施,取得了良好的效果。

某250m超高层建筑的塔楼结构设计分析

某超高层建筑高度为249.9m高度,位于6度设防地震烈度区,是采用叠合柱、型钢剪力墙并带有斜柱转换的框架-核心筒(双筒)结构体系。分析了整体结构在地震作用下的变化,并采用有限元软件着重分析了斜柱、型钢剪力墙和楼层楼板等构件的受力特点。结果表明,结构可满足“小震不坏、中震可修、大震不倒”的预期抗震性能目标要求,承载能力、变形能力、层间弹塑性位移、层间位移角可满足抗震性能目标C的各项抗震性能水准要求。

佛山国际体育文化演艺馆结构设计

佛山国际体育文化演艺馆为NBA级别的大型综合性甲级体育文化场馆。体育馆主体采用钢筋混凝土框架-剪力墙结构,大跨度屋盖采用带转换桁架的钢桁架结构。对地基基础、主体结构、预制混凝土看台、大跨度转换梁以及钢结构屋盖和转换桁架、结构超长等设计重点和难点进行了全面的论述。利用YJK、ETABS和SAP2000对整体结构以及钢结构屋盖进行了计算分析和包络设计,分析结果表明:整体结构和构件在各种工况下的指标均能满足规范要求,结构选型合理,受力体系明确,且有一定的安全冗余度。

某超限高层剪力墙结构抗震性能研究

文中以广西南宁市某超限工程为例,重点讨论了在结构设计中,需要解决的超限判定、计算要点、步骤、优化方法等问题。首先利用YJK和PKPM两个软件建立对比模型,从而相互验证所研究结构的刚度及承载力影响,完成了小震、中震的性能化分析;再用Midas/Building实现了模拟大震作用下的动力弹塑性损伤分析。结果表明,采取的结构加强措施能够基本满足设定的性能目标。

混凝土置换法在剪力墙结构加固中的应用研究进展

随着结构加固理论和技术的不断发展,越来越多的学者对混凝土置换加固技术展开了研究。文章总结了近年来混凝土置换加固技术工程应用以及设计理论的研究进展,分析了已有的研究成果和问题。分析表明:置换混凝土加固法可有效解决结构混凝土强度不足的问题,适用于承重结构受压区混凝土强度偏低或有局部严重缺陷的加固;然而,现有研究缺乏置换过程中对结构受力变形的控制指标以及能够广泛应用于实际置换工程当中的设计理论方法;在模拟免支撑混凝土置换过程时,应考虑施工过程中置换用材料的时变效应。未来,解决这些问题是工程应用与理论研究中值得关注的重点方向。

组合式钢筋混凝土预制框架电梯井道技术研究

为解决制约各地新老城区发展不均衡现象,提升老城区现代化程度及幸福指数,本文针对长期以来一些老旧小区的旧楼电梯加装成本的问题,旨在以钢筋混凝土框架结构为主体,运用混凝土结构预制、分段安装以及电梯构件预安装等技术,可在较大程度上降低电梯加装的整体工程造价。运用钢筋混凝土井道及电梯预安装技术,以尽可能少的投入,再加上各地政府的扶持,将对电梯加装的大范围推广具有积极意义。

某石砌体住宅楼UHPC抗震加固设计与分析

福建省某石结构体系经过鉴定,墙体承载力及抗震构造措施不满足鉴定标准要求,必须对墙体进行加固以消除安全隐患。依据抗震鉴定报告和现行规范标准要求,对比分析石砌体墙抗震加固方法的适用性,选择采用UHPC嵌缝加固法对石砌体墙进行抗震加固。通过墙体嵌缝加固设计,提出了具有嵌缝工作性的UHPC配合比,对加固前后石砌体墙的抗剪承载力进行验算分析。结果表明:UHPC嵌缝加固法可以明显提高石砌体墙的抗震性能,具有良好的推广和应用前景。

某商业中心酒店超限高层结构设计

某商业中心酒店为B级高度高层建筑,其存在扭转不规则、凹凸不规则、竖向构件间断、体型收进等多项不规则项,采用了基于性能化的抗震设计方法。依据不同性能目标,分别进行了小震、中震、大震作用下的整体计算分析、楼板应力分析。通过中震和大震的分析结果,找出结构的薄弱环节,有针对性地进行加强,结构整体抗震性能达到预期目标,结构体系合理安全。

Structural Analysis of a RC Shear Wall by Use of a Truss Model

Purpose of present work is to develop a reliable and simple method for structural analysis of RC Shear Walls. The shear wall is simulated by a truss model as the bar of a truss is the simplest finite element. An iterative method is used. Initially, there are only concrete bars. Repeated structural analyses are performed. After each structural analysis, every concrete bar exceeding tensile strength is replaced by a steel bar. For every concrete bar exceeding compressive strength, first its section area is increased. If this is not enough, a steel bar is placed at the side of it. For every steel bar exceeding tensile or compressive strength, its section area is increased. After the end of every structural analysis, if all concrete and steel bars fall within tensile and compressive strengths, the output data are written and the analysis is terminated. Otherwise, the structural analysis is repeated. As all the necessary conditions (static, elastic, linearized geometric) are satisfied and the stresses of ALL concrete and steel bars fall within the tensile and compressive strengths, the results are acceptable. Usually, the proposed method exhibits a fast convergence in 4 - 5 repeats of structural analysis of the RC Shear Wall.

型钢混凝土自复位双肢墙板的恢复力模型

为明确型钢混凝土(steel reinforced concrete,SRC)自复位双肢墙板的恢复力模型和参数确定方法,在低周往复加载试验的基础上,研究了双肢墙板在水平荷载作用下的破坏形态和工作机制。墙板的变形及破坏历程为:墙板摇摆和耗能器剪切屈服。墙板的破坏主要集中在耗能器上,具有良好的自复位能力。根据墙板的滞回特征,提出恢复力模型,包括骨架规则、卸载规则和反向加载规则三部分,并提出影响恢复力模型的10个参数。其中,3个刚度参数和3个强度参数确定骨架规则,4个位移参数确定卸载规则和反向加载规则。基于双肢墙板、预应力筋、耗能器和框架梁的协同工作机制,提出了影响恢复力模型的刚度参数、强度参数和位移参数的确定方法。与试验结果进行对比,试验滞回曲线与模拟得到的滞回曲线吻合较好,试验耗能和模拟耗能也基本一致。研究结果表明:本文提出的恢复力模型能较好地描述型钢混凝土双肢墙板的滞回特征,参数确定方法具有较好的分析精度。

基于MIDAS Gen的多层钢筋混凝土框架结构倒塌数值模拟分析

汶川地震中大量钢筋混凝土(reinforced concrete,RC)框架结构破坏严重,极震区其倒塌率却远超过多层砖混结构。2022年9月以来,四川频发地震,为重新探讨倒塌机理及抗震性能,本文研究通过实地震害及多层RC框架结构破坏形式,结合数值模型并应用MIDAS Gen有限元计算方法,研究了RC框架结构的倒塌机理、地震响应分析。结果表明:框架柱的破坏与屈服是RC框架倒塌的主要因素,模拟增设填充墙,当地震烈度达到10度时,层间位移角大约1/46,降低柱的轴压比,提高柱的破坏延性,增大结构的极限抗侧能力,起到抗震第一道防线的作用,避免整体屈服破坏。

超高车辆与箱梁立交桥碰撞简化计算模型评估分析

为了考察受超高车辆撞击装配式钢筋混凝土箱梁跨线桥的冲击动力和破坏行为,以一起近来发生的实际工程事故为案例进行精化有限元数值分析,并提出了双质量-并联弹簧(double mass-parallel spring,DM-PS)简化车辆模型,以有效地模拟超高车辆与桥梁的非对心碰撞行为。所建议DM-PS简化模型的有效性通过与两种广泛使用的车辆模型包括全尺(full scale,FS)模型和简单刚体(simple rigid,SR)模型的比较而得到充分地评估。计算结果表明:采用FS模型可得到与事故现场照片基本一致的跨线桥撞击区域破坏特征;SR模型高估结构的局部破坏,弱化结构的整体变形;DM-PS模型对于预测结构破坏具有较高的准确性。因此,所提出的DM-PS模型为超高车辆撞击桥梁结构防护设计提供了一个简单有效的分析手段。在此基础上,利用DM-PS模型进行了详细的结构行为参数分析,深入考察了车辆撞击速度、撞击质量、撞击位置以及结构形式等效应。所得到的结论为:相比撞击质量,结构的冲击动力行为对于撞击速度有更高的敏感性;跨中受撞和边跨受撞的变形和破坏模式有较大差异,边跨受撞对于单侧支座损伤更严重;箱梁内的箱板以及底板可以有效提高结构的抗冲击性能。