Experimental study on seismic behaviors of steel-concrete composite frames

Steel-concrete composite frames are seeing increased use in earthquake region because of their excellent structural characteristics, including high strength, stiffness, and good ductility. However, there exist gaps in the knowledge of seismic behavior and the design provisions for these structures. In order to better understand the seismic behaviors of composite frame systems, eight steel-concrete composite frames were designed. These composite frames were composed of steel-concrete composite beams and concrete filled steel tube columns. The axial compression ratio of column, slenderness ratio and linear stiffness ratio of beam to column were selected as main design parameters. The low reversed cyclic loading tests of composite frame system were carried out. Based on test results, the seismic behaviors of composite frames such as failure mode, hysteresis curve, strength degradation, rigidity degradation, ductility and energy dissipation were studied. Known from the test phenomenon, the main cause of damage is the out-of-plane deformation of steel beam and the yielding destruction of column heel. The hysteretic loops of composite frame appear a spindle shape and no obvious pinch phenomenon. The results demonstrate that this type of composite frame has favorable seismic behaviors. Furthermore, the effects of design parameters on seismic behaviors were also discussed. The results of the experiment show that the different design parameter has different influence rule on seismic behaviors of composite frame.

Mechanical performance of shear studs and application in steel-concrete composite beams

This work experimentally investigates the effects of shear stud characteristics on the interface slippage of steel-concrete composite push-out specimens. ABAQUS is used to establish a detailed 3D finite element(FE) model and analyze the behavior of push-out specimens. The modeling results are in good agreement with the experimental results. Based on parametrical analysis using the validated FE approaches, the effects of important design parameters, such as the diameter, number, length to diameter ratio, and yield strength of studs, concrete strength and steel transverse reinforcement ratio, on the load-slip relationship at the interface of composite beams are discussed. In addition, a simplified approach to model studs is developed using virtual springs with an equivalent stiffness. This approach is demonstrated to be able to predict the load-displacement response and ultimate bearing capacity of steel-concrete composite beams. The predicted results show satisfactory agreement with experimental results from the literature.

Bending Stiffness of Truss-Reinforced Steel-Concrete Composite Beams

This paper is concerned with a special steel-concrete composite beam in which the resisting system is a truss structure whose bottom chord is made of a steel plate supporting the precast floor system. This system works in two distinct phases with two different resisting mechanisms: during the construction phase, the truss structure bears the precast floor system and the resisting system is that of a simply supported steel truss;once the concrete has hardened, the truss structure becomes the reinforcing element of a steel-concrete composite beam, where it is also in a pre-stressed condition due to the loads carried before the hardening of concrete. Within this framework, the effects of the diagonal bars on the bending stiffness of this composite beam are investigated. First, a closed-form solution for the evaluation of the equivalent bending stiffness is derived. Subsequently, the influence of geometrical and mechanical characteristics of shear reinforcement is studied. Finally, results obtained from parametric and numerical analyses are discussed.

The Study of Force and the Mechanical Characteristic of Incremental Launching Construction Method on a Steel-Concrete Continuous Beam Bridge

The usage of steel-mixed composite beams is quite extensive today.During an event of constructing steel-mixed composite bridges,the incremental launching construction method is generally adopted.This paper mainly analyzes the force of incremental launching construction on a steel-concrete continuous beam bridge,the classification of incremental launching construction,the application of incremental launching construction in steel-mixed composite beams,the temporary facilities existing in incremental launching construction as well as their existing problems.Lastly,the analysis of the stress of composite beams in incremental launching construction is described by using the reference for the construction of mixed composite continuous beam bridges provided.

装配式型钢混凝土叠合框架梁连接节点构造设置与安全分析

住房和城乡建设部印发《“十四五”建筑业发展规划》提出大力发展装配式建筑、推动生产和施工智能化升级的主要任务。而国内目前采用的预制叠合框架梁存在着跨度大自重大吊装成本高、预制梁柱节点位置易发生钢筋碰撞吊装定位难度大等问题,限制了装配式建筑结构的发展。结合实际工程项目,提出一种新型的装配式型钢混凝土叠合框架梁,并对该叠合梁的构造设置、连接方式及安全性进行分析,从而为装配式框架结构、框架—剪力墙结构等装配式建筑中框架梁的深化设计提供一种新的拆分方案。

PEC柱-钢梁摩擦耗能部分自复位组合框架抗震试验研究

为系统研究梁柱采用自复位连接组合框架的抗震机理,选取预拉杆长度设置、PEC柱截面强弱轴布置和柱脚连接方式3个设计参数,设计制作了4榀PEC柱-钢梁梁柱摩擦耗能部分自复位连接组合框架1∶2缩尺试件并进行拟静力抗震试验。通过试验现象观察和数据分析,对试件的滞回特性、抗侧刚度退化、复位能力、滞回耗能等抗震性能进行研究。结果表明:摩擦耗能部分自复位连接通过T形件长圆孔合理设置实现了“设计地震水平阶段实现复位,大震设计水平阶段自复位连接连接转化为伴随出现螺栓承压型受力实现部分自复位”的性能化设计目标;设计地震阶段,试件主要通过辅助摩擦耗能件耗能,且卸载残余侧移小于自复位结构侧移限值(0.3%),在大震作用阶段,试件通过辅助摩擦耗能件与结构构件损伤联合耗能,承载能力仍继续增大,且仍具有部分自复位能力;预拉杆设置有限长度可显著增强结构整体性,PEC柱弱轴布置一定程度上降低了结构整体性,而PEC柱脚采用铰接可显著削弱结构整体性。

PK梁板在装配整体式框架结构中的应用

针对PK预应力混凝土叠合梁、预应力混凝土叠合梁同时在一个工程中应用遇到的模板设计与计算、起重设备的选型和吊具选择以及施工工艺等问题,结合工程实际情况,形成了PK预应力混凝土叠合梁板组合的施工工艺流程,确保PK预应力混凝土叠合板吊装的精确定位及受力性能,满足工程质量要求。

钢混组合梁连续刚构桥施工控制影响因素研究

以浙江省宁波市舟山港跨海大桥北通航孔桥工程为项目背景,采用Midas civil软件建立桥梁有限元模型,选取结构几何形态参数、截面特征参数、时间特性参数、荷载参数和材料特性参数作为施工控制参数,并考虑桥梁施工工艺进行施工控制参数敏感性分析。分析结果表明,采用支座顶升施工工艺的钢混组合梁连续刚构桥,在成桥阶段结构线形和结构应力易受预应力钢束初始控制预应力和混凝土重度这两类施工控制影响因素的影响;在施工过程中采用支座顶升施工工艺调整桥梁结构线形,会导致初始控制预应力参数和年平均相对湿度参数敏感性分析结果在支座顶升位置处发生突变。研究结果可为钢混组合梁连续刚构桥的施工控制提供参考依据。

Field validation of UHPC layer in negative moment region of steel-concrete composite continuous girder bridge

Improving the cracking resistance of steel-normal concrete(NC)composite beams in the negative moment region is one of the main tasks in designing continuous composite beam(CCB)bridges due to the low tensile strength of the NC deck at pier supports.This study proposed an innovative structural configuration for the negative bending moment region in a steel-concrete CCB bridge with the aid of ultrahigh performance concrete(UHPC)layer.In order to investigate the feasibility and effectiveness of this new UHPC jointed structure in the negative bending moment region,field load testing was conducted on a newly built full-scale bridge.The newly designed structural configuration was described in detail regarding the structural characteristics(cracking resistance,economy,durability,and constructability).In the field investigation,strains on the surface of the concrete bridge deck,rebar,and steel beam in the negative bending moment region,as well as mid-span deflection,were measured under different load cases.Also,a finite element model for the four-span superstructure of the full-scale bridge was established and validated by the field test results.The simulated results in terms of strains and mid-span deflection showed moderate consistency with the test results.This field test and the finite element model results demonstrated that the new configuration with the UHPC layer provided an effective alternative for the negative bending moment region of the composite beam.

钢筋桁架楼承板及其在装配式混凝土框架结构体系中的应用研究

为更好地在装配式混凝土框架结构中应用钢筋桁架楼承板,提出一种钢筋桁架楼承板的设计方法。对比分析钢筋桁架板与预制叠合混凝土板的特点,钢筋桁架楼承板可以在板底不做竖向支撑的情况下跨空浇筑混凝土,底钢板及钢筋笼自重较轻,与钢筋桁架叠合板相比,更易于装配,可以节约施工能耗。其板底铁皮影响外观,适用跨度较小,且成板较厚,在住宅类建筑中不太受欢迎,但在非住宅工程中,综合效果显著优于预制叠合混凝土板。根据实际工程设计经验,提出:钢筋桁架楼承板采用钢次梁,用于装配式混凝土框架结构体系的构造做法,以弥补其跨度小,板太厚造成浪费的缺点。

高速铁路大跨度混合梁连续刚构设计关键技术研究

广湛高铁采用(109+2×200+109)m混合梁连续刚构跨越西江主航道,主梁采用预应力混凝土梁+钢混结合梁的混合梁形式,与预应力混凝土连续刚构相比,减轻了结构自重,降低了主梁弯矩和剪力,提高了桥梁跨越能力;跨中采用钢混结合梁,减小了因混凝土收缩徐变对结构后期变形的影响,改善了结构受力和高速行车条件。钢混结合段为钢主梁与预应力混凝土主梁的连接构造,是混合梁桥关键传力部位,根据刚构桥的钢混结合部受力模式,设置于主梁受力较小位置,采用有格室后承压板式结合部构造。通过对钢梁截面分析比选,采用符合结构受力特点、经济性较好的槽形钢箱混凝土结合梁,并对槽形钢梁超高腹板稳定性、空腹桁架式横隔板构造等关键技术进行研究。建造方案推荐采用挂篮悬臂浇筑混凝土梁,钢梁采用整体吊装安装,混凝土桥面板采用分块预制,可有效保证施工工期。

西安某空间曲面混合框架结构设计与分析

西咸空港综合保税区事务服务办理中心结构高度29m,为不规则空间曲面混合框架结构。采用一系列沿球面经线放射状布置的箱形曲线钢管承重钢肋,实现了建筑空间曲面造型;利用屈曲约束支撑灵活布置的特点,解决了南北建筑不规则平面的刚度不均匀问题;采用金属摩擦摆全向滑动支座,解决了南北建筑独立单元地震作用下相互影响问题。采用YJK和MIDAS Gen软件分别对结构进行小震弹性及中震弹性、中震不屈服分析。结果表明,结构受力性能满足要求,可以达到抗震性能的设计目标。

上跨平交口型钢现浇板钢混叠合梁施工技术研究

在传统钢混叠合梁施工技术基础上,研发了上跨平交口型钢现浇板钢混叠合梁施工技术。论文对此技术进行详细介绍。该技术解决了平交口施工效率及施工安全问题。

宜城汉江铁路特大桥主桥方案设计研究

研究目的:宜城汉江特大桥为新建襄阳至荆门高速铁路的关键控制性工程,主桥采用2×200 m双主跨跨越汉江通航水域。通过研究主桥桥跨布置及支承体系,从技术性、经济性等方面综合比选斜拉加劲刚构连续梁和钢-混组合(混合)梁刚构连续梁两种桥式方案。研究结论:(1)两种方案均为适用方案,斜拉加劲刚构连续梁方案在刚度条件、长期线形稳定性、技术成熟性、工程实践经验、维修养护和景观效果等方面有优势;(2)斜拉加劲刚构连续梁方案通过采用“高中塔、低边塔”的桥塔布置,保证合理结构受力并避免边支座负反力;(3)结构计算表明结构受力安全可靠,列车行车安全性、旅客乘坐舒适性均满足要求;(4)本设计成果可为类似铁路桥梁提供参考。

装配式先张法预应力叠合梁设计及应用

介绍了施工免支撑先张法预应力混凝土框架叠合梁两阶段设计的方法,并以贵阳市某AA级装配式工业厂房为背景,与常规装配整体式框架结构进行了对比分析。结果表明:采用装配式先张法预应力混凝土框架梁的梁端负弯矩显著降低,跨中正弯矩显著增大;可大幅度减少梁支座钢筋用量,并充分利用高强度钢绞线降低梁高和跨中钢筋用量,有效降低建筑材料用量和碳排放量,同时大幅减少进入梁柱节点核心区的钢筋数量,提高建造速度,降低建造风险和建造成本。对于大荷载大跨度大层高的工业厂房建筑,采用免支撑先张法预应力混凝土框架叠合梁,可实现比常规装配整体式框架结构更低的造价和更快的建造速度,具有很好的推广应用价值。

圆形截面柱组合框架中非对称钢梁截面框架梁梁端极限状态有效翼缘宽度研究

楼板有效翼缘宽度是组合框架梁梁端极限承载力验算的关键参数之一,已有的有效翼缘宽度计算公式存在荷载模式不匹配、等效准则不匹配、无法考虑钢梁截面的非对称性等不足。为此,该文重点讨论了侧向荷载作用下采用圆形截面柱的组合框架中非对称钢梁截面框架梁端的承载力极限状态有效翼缘宽度的计算方法。在有限元软件MSC.MARC(2018)中建立精细化数值模型,通过单变量分析筛选出对有效翼缘宽度有显著影响的关键变量。在合理的取值范围内对这些关键变量进行充分的排列组合,得到一系列的数值算例结果。对这些数值结果进行回归分析,基于前人得出的对称钢梁截面情况的计算公式,保留其基本框架而修改其中相关参数,得出侧向荷载作用下非对称钢梁截面组合框架梁有效翼缘宽度的计算方法。

高速铁路钢-混混合梁连续刚构桥一体化建造技术研究

本文以某高速铁路双主跨钢-混混合梁连续刚构桥施工为背景,经过深入分析研究,创新性地研发了大跨径T构大吨位悬臂浇筑+钢混结合段吊装及混凝土浇筑+整节段钢梁吊装一体化装备;研发了大型浮吊提升边跨整节段钢梁,结合一体化装备实现体系转换架梁关键技术;研发了双主跨钢-混混合梁部分配载分步合龙关键技术等一系列大跨双主跨钢-混混合梁建造新技术,提高了施工效率,确保了施工质量,创造了良好的经济及社会效益,为同类桥梁施工提供了有益借鉴。

绥芬河青云市场套(扩)建工程结构设计与施工措施研究

结合绥芬河青云市场套(扩)建改造工程实践,提出了在施工阶段只在原房屋结构顶侧实现新增套(扩)建框架与原房屋框架的类链杆连接,待新增套(扩)建结构沉降充分后,再实现新旧结构在各层的链杆连接的设计思路。通过在原结构顶与外套框架柱间设置混凝土垫块,并在二外套框架柱间布置并张拉预应力筋,来实现施工阶段外套框架柱与原结构顶的类链杆连接。在新增结构施工完成后,将原结构顶上皮标高处二外套框架柱中预埋钢筋焊接连通,并浇筑一定厚度混凝土,来实现在原结构顶标高处新旧结构间的永久性可靠连接。将原框架节点的后植钢筋与外套框架柱的预埋钢筋焊接连接,来实现新旧结构在各层的链杆连接。为确保施工过程中原房屋的正常使用,提出了用挂模钢桁架来承托内置钢桁架-混凝土组合框架梁施工阶段荷载,用挂模钢箱来承托内置钢箱-混凝土组合次梁施工阶段荷载,用垂直于次梁内置钢箱焊接的型钢主楞来承托楼板荷载的施工阶段自承重混凝土楼盖设计与施工方法。

带组合扁梁多层轻型钢框架结构体系分析

结合某多层钢结构住宅示范楼的设计 ,着重讨论了组合扁梁楼盖在大开间住宅体系中的应用及设计方法。分析结果表明 ,对于大开间住宅 ,采用组合扁梁楼盖不仅能够很好地满足建筑方面的要求 ,显著地降低建筑的层高 ,减少围护结构的费用和减轻基础压力 ,而且能够减少结构的总用钢量 。