楼面边主梁次扭矩的计算

大跨度预应力混凝土次梁楼盖结构体系中,就设计者所关心的边主梁预应力次扭矩问题进行了讨论,并给出了计算方法和计算实例.     

等代均布荷载法在不等跨预应力次梁结构中的简化计算

利用预应力次梁等效荷载对边主梁的有利影响,在不等跨预应力连续梁结构体系中降低非预应力边主梁扭矩,解决了中间支座不平衡弯矩分配问题,从而方便了楼盖结构的设计。     

大跨预应力次梁楼盖结构的边主梁扭矩简化计算

利用预应力次梁等效荷载对边主梁的有利影响,降低非预应力边主梁扭矩,并对多段预应力布筋形式产生的多段等效荷载进行了改进,利用实用等效荷载方法把多段均布荷载转化为满跨均布荷载,从而方便了楼盖结构的设计。     

某铁路站房大跨楼盖结构分析设计

某铁路站房候车大厅为24m×24m双向大跨钢筋混凝土结构,楼盖结构分析了井字梁方案和单向次梁方案,按本工程情况选用第2种方案.单向大跨次梁搁置在大跨度主梁上,在主梁上形成较大扭矩,主梁验算不满足截面条件.本工程通过布置次梁预应力筋,预应力等效荷载平衡部分竖向荷载,并控制次梁梁端预压力弯矩,减少主梁扭矩,保证了结构安全,...     

大跨度预应力混凝土次梁结构体系中的边梁受扭问题浅析

本文就大跨度预应力混凝土次梁楼盖结构体系中 ,设计者所关心的边梁受扭问题进行了讨论。文中根据空间弯扭协调理论 ,按弹性分析得出了次梁与边梁的弯 扭变化规律 ,并对预应力的扭转效应进行了研讨 ,得到了一些有意义的结论     

大跨度双向正交部分预应力混凝土梁的设计与分析

大跨度预应力次梁对主梁产生的扭矩与结构施工顺序有关。对武汉国际会展中心主楼32.0m×17.0m跨构成的双向正交部分预应力混凝土梁进行各个施工阶段的内力计算,表明主梁的抗扭设计不能简单地对主梁的扭矩乘以扭矩折减系数后进行配筋,而应先计算次梁在每个施工阶段对主梁产生的扭矩,然后进行叠加。同时也提出主梁所施加的预压力Np0对主梁抗扭是有利的,在设计中可考虑这一有利因素。     

阶梯教学楼大跨度预应力次梁楼盖结构设计

介绍了重庆邮电学院教学楼楼盖结构和预应力次梁的详细设计过程 ,探讨了边主梁抗扭的问题 ,并提出了一些工程处理办法。另外还对主梁与预应力次梁斜交的节点构造作了介绍 ,可供类似工程参考     

重庆美心门业集团厂房预应力楼盖结构设计

以一个3层4跨工业厂房为实例,介绍了大跨度预应力次梁楼盖结构体系的设计。对结构方案的选择做了相关的分析和比较,对预应力梁选定截面尺寸、跨度、施工方案及构造措施做了介绍,对主梁的抗扭设计、配筋方式及柱的截面选取和轴压比控制等关键问题进行了介绍。     

大跨预应力次梁楼盖结构体系设计

介绍与传统设计手法不同的“大跨预应力次梁楼盖结构体系”，并对该体系结构中结构布置、主梁设计、预应力次梁设计予以介绍说明。     

大跨度无粘结预应力交叉梁楼盖的设计及施工

介绍了某大学教学楼大跨度无粘结预应力交叉梁楼盖的结构布置方案,结构计算方法及预应力钢筋的布置,并提出了预应力的施工方案,以推广大跨度无粘结预应力交叉梁楼盖的应用。     

武昌火车站大跨钢—混凝土组合楼盖承载力试验研究

对武昌火车站候车厅大跨钢-混凝土组合楼盖进行了分级实荷试验,实测各级荷载作用下关键构件的应变及挠度,以检验其承载力.试验结果表明,实测与理论分析结果基本一致,结构承载性能良好,为同类结构的设计应用提供了可靠的试验依据.     

基于加速度响应的体育馆大跨度楼盖竖向振动有限元分析

结合某实际工程,设计11种楼盖方案,并通过5种不同荷载工况下的人致跳跃荷载所致楼盖竖向振动有限元模拟分析研究,得到有关人致荷载下大跨度楼盖结构竖向振动的主要结论:类共振、二分频类共振有可能成为体育馆大跨度楼盖竖向振动舒适度评价中的控制工况;增大楼盖自振频率可避免发生二分频类共振,但调整后应防止三分频类共振或者其他高频非类共振工况成为控制工况;采用峰值加速度对类共振工况下的舒适度评价较为适用,而非类共振工况下则应同时考虑峰值加速度及其持续时间的综合评价方法;增加梁高及增设平梁底板能有效控制大跨度楼盖结构在人致荷载作用下的竖向振动,在增设平梁底板的情况下增大底板厚度的效果更为明显,而增加楼板板厚则效果不明显。     

跳跃荷载作用下体育馆大跨预应力次梁楼盖振动模拟分析

以某小学体育馆为工程背景,通过ANSYS建立有限元模型,考虑不同跳跃频率、跳跃人数和跳跃次数的荷载作用,对大跨度预应力混凝土次梁楼盖结构进行竖向振动模拟分析,并进行现场实测,结果表明:修正半正弦平方荷载模型模拟单人跳跃荷载所得分析结果与实测值相对误差为12.98%,比较接近;多人同步跳跃所导致的楼盖竖向振动加速度随人数的增加而增加,近似呈正比关系;考虑多人跳跃难以严格同步,引入倍增因子对跳跃荷载模型进行修正,与实测值验证较为接近。     

扁梁楼盖中组合节点的试验研究

进行组合扁梁楼盖中梁柱钢节点及组合节点的足尺试验。试件由钢管混凝土组合柱及轴对称钢梁与组合柱通过剪切钢板连接的组合楼盖组成。进行部分包裹混凝土组合梁的试验,确定扁梁楼盖锚钉的布置点。试验结果表明:组合节点和钢节点均为半钢性节点,且各自单独锚固;楼盖对提高节点抗弯承载力起重要作用。     

大跨预应力次梁楼盖结构体系经济性分析

根据几类已建工程的调查统计、分析对比,对与传统设计手法不同的大跨预应力次梁楼盖结构体系的经济合理性做了详细分析,结果表明这种体系方案合理,综合经济效果显著.     

Composite connections in slim-floor system: An experimental study

This paper reports the results of full-scale tests in beam-to-column connections for composite slim floor systems, including tests on Bare Steel connection and composite connection. The tested system consists of a concrete-filled composite column and a composite floor where an asymmetric steel beam is connected to a composite column by shear steel plates. Tests results previously obtained on partially encased composite beams were used to define the position of the headed studs in the slim floor system. Based on the obtained results of connections, the composite and Bare Steel connection behaved as semi-rigid and nominally pinned respectively. The tests results also indicated a significant contribution of the slim floor to the moment capacity of the connection.     

Vibration serviceability of pre-stressed concrete floor system under human activity

A comprehensive research was undertaken to study the vibration serviceability of a long-span pre-stressed concrete floor system intended to be used in an indoor badminton court, using the field test and finite element method. Specifically, heel-drop was adopted to capture the natural frequencies and modal damping ratios of the floor system and the tests for jumping impact and different types of human excitations (walking, running and hopping) were performed to capture the acceleration responses. The floor system is found to have low frequency and modal damping ratio. The comparison of the experimental results with the published values from China’s design code, AISC design guide and PCI design handbook indicates that the pre-stressed concrete floor system exhibits satisfactory vibration perceptibility overall. The acceleration threshold value given in the China’s code and AISC design guide may be conservative for the pre-stressed concrete floor under hopping excitation. For determining the fundamental natural frequency analytically, fixed-pinned support condition is recommended for accounting for the effect of adjacent structures on floor stiffness. Coefficients β_rp is proposed to calculate the RMS acceleration conveniently by hand.     

民大广场A楼结构抗震设计

民大广场A楼为带转换层的型钢框架-剪力墙结构体系,因建筑功能的需要,结构外框架不设框架梁,外框架柱为纺锤状斜柱,转换层采用新型组合结构转换梁。所采用的结构通过基于性能的抗震分析、拟静力试验和振动台试验等验证是可行的,其破坏机制遵循"强柱、弱梁、更强转换梁、最强节点区"的原则。双型钢混凝土转换梁具有较强承载能力和较好耗能性能。     

行走激励下大跨度空腹夹层板结构振动舒适度分析

随着大跨结构的发展,舒适度已成为评价楼盖结构性能的重要指标。针对大跨度空腹夹层板楼盖,考虑行走路线和步行频率影响进行了振动响应计算。分析表明,空腹夹层板的自振特性类似于实心平板,低阶振型主要表现为竖向振动;采用行走路线法评价楼盖舒适度时,应根据实际情况采用较长的路线并使其通过低阶振型中心;定点激励法计算的峰值加速度要低于通过低阶振型中心行走路线的计算结果,据此评价楼盖舒适度是有局限性的;楼盖上不同感受点的加速度响应峰值是不同的,较大的加速度响应峰值只出现在低阶振型中心周围。     

Nonlinear behaviour of unprotected composite slim floor steel beams exposed to different fire conditions

An efficient nonlinear 3D finite element model has been developed to investigate the structural performance of composite slim floor steel beams with deep profiled steel decking under fire conditions. The composite steel beams were unprotected simply supported with different cross-sectional dimensions, structural steel sections, load ratios during fire and were subjected to different fire scenarios. The nonlinear material properties of steel, composite slim concrete floor and reinforcement bars were incorporated in the model at ambient and elevated temperatures. The interface between the structural steel section and composite slim concrete floor was also considered, allowing the bond behaviour to be modelled and the different components to retain its profile during the deformation of the composite beam. Furthermore the thermal properties of the interface were included in the finite element analysis. The finite element model has been validated against published fire tests on unprotected composite slim floor steel beams. The time–temperature relationships, deformed shapes at failure, time–vertical displacement relationships, failure modes and fire resistances of the composite steel beams were evaluated by the finite element model. Comparisons between predicted behaviour and that recorded in fire tests have shown that the finite element model can accurately predict the behaviour of the composite steel beams under fire conditions. Furthermore, the variables that influence the fire resistance and behaviour of the unprotected composite slim floor steel beams, comprising different load ratios during fire, cross-section geometries, beam length and fire scenarios, were investigated in parametric studies. It is shown that the failure of the composite beams under fire conditions occurred for the standard fire curve, but did not occur for the natural fires. The use of high strength structural steel considerably limited the vertical displacements after fire exposure. It is also shown that presence of additional top reinforcement mesh is necessary for composite beams exposed to short hot natural fires. The fire resistances of the composite beams obtained from the finite element analyses were compared with the design values obtained from the Eurocode 4 for composite beams at elevated temperatures. It is shown that the EC4 predictions are generally conservative for the design of composite slim floor steel beams heated using different fire scenarios.