新型组合梁板连接中板的抗弯性能

在高层建筑结构设计中,由于上部荷载较大或梁的跨度较大,使得梁的截面高度较高,通常会影响建筑的有效层高和建筑的总体高度。为了减小各层梁板结构高度,有效增大各层净高,提出了一种钢箱梁嵌入现浇板的新型组合梁板连接方式。针对这种新型连接方式,对6个钢箱梁混凝土板组合连接区域进行了板承受支座负弯矩的单调加载试验,对比分析了采用钢箱梁嵌入混凝土板组合楼盖与传统栓钉连接组合楼盖中板抵抗支座负弯矩的性能差异;并利用ABAQUS对试件进行了有限元分析。试验与有限元分析结果表明:采用钢箱梁嵌入板连接组合方式,其混凝土板抵抗支座负弯矩的能力与传统连接方式板抵抗支座负弯矩能力没有明显差异。     

竖向荷载作用下整浇梁板的空间效应试验研究

对2个空间整浇梁板试件进行了竖向静力加载试验,并通过与不带板的梁试件及平面截断梁板试件的对比和非线性有限元分析,研究了竖向荷载作用下整浇梁板的空间效应对梁受力性能的影响。非线性有限元分析结果与试验结果基本吻合。试验与分析结果表明:空间梁板试件的边支座直交梁出现扭转裂缝,楼板上的裂缝多斜向分布,梁边支座截面及直交方向梁、板截面均存在一定的弯矩,空间梁板试件存在明显的空间传力路线;空间梁板试件的梁跨中先出现塑性铰,而在支座截面出现塑性铰之前,发生梁支座截面受压区混凝土压碎或支座附近剪切破坏,这种破坏模式与平面截断梁板试件基本相同,而与不带板的梁试件的破坏模式完全不同;整浇梁板的空间效应大幅度提高了梁的刚度和承载能力。     

简支钢板-混凝土组合板抗弯承载性能的有限元分析

主要分析钢板-混凝土组合板各参数对简支组合板抗弯承载性能的影响。利用有限元软件ANSYS软件对4组影响钢板-混凝土组合板性能的主要参数进行了分析,包括栓钉间距、钢板厚度、剪跨比、试件的长宽比等。模拟了构件加载的全过程,并将其计算结果与采用截面分析法的计算结果作对比。分析结果表明,提高剪力连接程度可以使钢和混凝土的材料性能得到充分发挥;钢板厚度的增加会对抗弯承载力有不同程度的提高作用;加载点越靠近支座,组合板的长宽比越小,组合板的抗弯承载力越大。截面分析法对于分析完全剪力连接的钢板-混凝土组合板效果良好。     

体外预应力混凝土连续梁的弯矩重分布试验研究

进行了3根体外预应力混凝土两跨连续梁受力全过程试验。试验表明,自加载至受拉区混凝土开裂前,连续梁处于弹性阶段,边支座、中支座反力、跨中截面和中支座截面弯矩的实测值与采用弹性理论计算值接近。受拉区混凝土开裂后至非预应力受拉钢筋屈服,边支座反力及跨中截面弯矩实测值开始向大于弹性理论计算值的方向偏离;而中支座反力及中支座截面弯矩实测值则向小于弹性理论计算值的方向偏离。当梁内受拉非预应力筋屈服后,边支座、中支座反力的实测值以及跨中截面弯矩和中支座截面弯矩实测值与弹性理论计算值的偏差进一步增大,这种偏差在试验梁破坏时达到最大。3根试验梁中支座截面弯矩重分布值分别为12.8%、16.9%及14.6%。试验实测值还与4个不同设计规范的弯矩重分布计算值进行了比较。结果表明:采用美国ACI 318-95规范及中国GB 50010-2010规范计算的中支座截面弯矩重分布值均小于试验实测值;除一根编号为B5的梁外,加拿大A23.3-M84规范的预测值与试验值最为接近;而英国BS8110规范则偏于不安全。实际设计中,可按中国规范公式来计算体外预应力混凝土连续梁的弯矩重分布,但必须合理确定体外预应力筋的极限应力。     

钢-闭口型压型钢板轻骨料混凝土组合梁受力性能试验研究

完成了8个钢-闭口型压型钢板轻骨料混凝土组合梁试件的静力试验,对组合梁受力性能进行了研究。试验中详细考察了钢-闭口型压型钢板轻骨料混凝土组合梁在不同名义剪跨比、不同栓钉布置形式下的受力过程、裂缝发展、破坏形态和型钢、钢板与混凝土应变发展过程、跨中弯矩与跨中挠度以及型钢与组合板端部滑移发展情况;根据对试验结果与现行规范所建议方法计算结果的对比分析,提出了钢-闭口型压型钢板轻骨料混凝土组合梁的受弯承载能力以及受剪承载能力计算方法。研究结果表明,钢-闭口型压型钢板轻骨料混凝土组合梁试件的破坏形态主要表现为弯曲剪切破坏,组合梁具有较好的承载能力和延性,在80%Pu后,组合梁界面才表现出明显的滑移现象,截面不满足平截面假定。研究还表明,即使组合梁试件按照我国现行规范计算所得连接程度较小时,也具有较高的受弯承载能力。同时,为考察组合梁动力特性,对8个组合梁试件的前三阶自振频率和阻尼比进行了试验测试,测试结果表明组合梁阻尼比较     

缩口型压型钢板-混凝土组合板的承载力及变形(一):试验研究及纵向抗剪承载力

共进行了8块组合板试验,研究了缩口型压型钢板-混凝土组合板的破坏特征、纵向抗剪、抗弯等力学性能。试验结果表明,对组合板承载力起控制作用的是纵向剪切破坏和弯曲破坏,对于端部无栓钉的组合板,随剪跨比Ls/dp的增大,破坏形态会逐渐由纵向剪切破坏向弯曲破坏过渡;端部栓钉可以有效改善组合板在极限状态时的受力性能。在试验研究的基础上,分别采用m-k法和部分剪力连接法回归得到了计算该类型压型钢板组合板纵向抗剪承载力的必要参数,同时分析了端部栓钉的有利作用。两种方法均能较准确地预测板的极限承载力。     

钢板-混凝土组合板受弯性能试验研究

以钢板代替受力钢筋,通过栓钉将外侧钢板与内部混凝土板相连,二者共同作用形成钢板-混凝土组合板。根据钢板布置形式的不同,可将钢板-混凝土组合板分为单面钢板-混凝土组合板（SSC）和双面钢板-混凝土组合板（DSC）。通过对4个SSC试件和3个DSC试件的受弯试验研究,分析了不同钢板厚度、抗剪连接程度以及构造钢筋配置对组合板受弯性能和破坏形态的影响。试验结果表明,按完全抗剪连接设计的试件破坏形态与适筋梁相似,具有良好的受弯承载能力和延性;当受拉区钢板采用部分抗剪连接设计时,剪跨区栓钉易剪断导致承载力明显降低;当受压区钢板采用部分抗剪连接设计时,顶层钢板易发生局部屈曲,导致试件承载力和延性有所降低。基于试验结果,给出了钢板-混凝土组合板的受弯承载力计算式,计算值与试验值吻合较好。     

两跨无粘结预应力混凝土连续板抗火性能试验与分析

完成了9块两跨无粘结预应力混凝土连续单向板抗火试验。通过布置于试验板内的热电偶,获得了试验板截面的温度场分布。通过布置于无粘结筋锚固端的力传感器和试验板上的位移传感器,获得了试验板中无粘结筋应力和试验板新增变形在火灾下的变化过程。通过布置于各试验板边支座上的压力传感器,获得了两跨连续板支座反力在火灾下的变化过程。受火过程中试验板背火面经历了水分溢出、水蒸气形成和发展、溢出水干涸及水蒸气消失的过程。基于不同试件不同时刻的无粘结钢丝应力实测值、边支座反力实测值、跨中新增变形实测值,拟合出了考虑各关键参数影响的火灾下两跨连续板中无粘结钢丝应力计算公式、边支座反力计算公式和跨中新增变形计算公式。针对在抗火试验中有4块试验板板顶负弯矩的钢筋截断处出现了贯穿裂缝的现象,提出了火灾下两跨连续板中支座两侧负弯矩钢筋的截断建议。     

钢-部分预应力混凝土连续组合梁内力重分布研究

本文报道了10榀钢-部分预应力混凝土连续组合梁和1榀钢-普通混凝土连续组合梁的极限承载力试验结果。试件为两跨连续梁,主要试验参数为负弯矩区部分预应力比PPR、综合力比Rp及栓钉连接程度。试验采用跨中单调一次加载。试验发现,在负弯矩区施加预应力的钢-部分预应力混凝土连续组合梁可产生较充分的内力重分布,其主要影响因素为截面相对受压区高度ξu和负弯矩区综合力比Rp。本文通过试验研究和理论分析,提出了钢-部分预应力混凝土连续组合梁满足承载力要求的弯矩调幅限值犤β犦的计算公式,其计算结果与试验结果吻合较好。     

钢板混凝土板平面外弯剪性能试验研究

对5片剪跨比范围在2~5、距厚比为100和150的钢板混凝土板进行简支单点加载的平面外抗剪性能试验。试验结果表明:钢板混凝土板的破坏形式与钢筋混凝土结构类似;栓钉的间距对钢板混凝土(简称"SC")板的刚度有很大影响;随着剪跨比的增大,抗剪承载力下降,试件破坏呈现脆性破坏;当试件截面高度增加时,试件破坏形式为剪切破坏。同时采用ACI 349和JEAG 4618对试件弯曲承载力和抗剪承载力进行计算,计算值与试验值吻合较好。     

Strengthening multiple span simply-supported girder bridges using post-tensioned negative moment connection technique

A post-tensioned negative moment connection technique is proposed to strengthen old multiple span simply-supported T-section reinforced concrete (RC) girders. In this technique, old concrete is removed from girder ends and flanges, a diaphragm is placed between the two adjacent girder ends over the interior support and negative moment steel strands are installed in new cast-in-place concrete and post-tensioned to make continuity. A total of six two-span simply-supported T-section RC girders were cast and five of them strengthened using the provision of the proposed post-tensioned negative moment connections. Both laboratory tests and nonlinear finite element (FE) analysis were conducted to investigate the structural performance of the strengthened RC girders. The moment redistribution in the strengthened continuous RC girders was also measured and is discussed. It is shown that the proposed post-tensioned moment connection technique can reliably transfer the negative moment over the support and markedly increase member stiffness and the load-carrying capacity of existing multiple span simply-supported RC girders. The validity of the FE analysis was also demonstrated through comparisons with experimental results.     

Experimental study on inelastic mechanical behaviour of composite girders under hogging moment

Negative bending moments acting on the support regions of continuous composite girders generate tensile stresses in the concrete slab and compressive stresses in the lower steel profile. As a result, the mechanical behaviour of these girders becomes strongly nonlinear, which needs special study. In this paper, static experimental tests on four half-scale models of steel and concrete composite girders with different shear connectors such as studs and Perfo-Bond Strips (PBLs) under hogging moments are cautiously conducted in order to investigate the reduction of flexural stiffness and the inelastic behaviour after cracking. In the test results, crack development, crack widths and strains of the composite section before and after cracking were observed. The crack width evaluation methods based on design codes for steel and concrete composite girders under negative bending moment were compared. Crack widths should be controlled appropriately within an allowable value in the slab under service load. The strains in reinforcing bars obtained through the static tests agreed well with the values calculated through the application of the existing tension stiffening theory. The test specimens could be assumed to be a full composite section until the ultimate state on the basis of load and slip relationship results of shear connectors. It follows that analytical and experimental studies can be served as a basis for the design of continuous composite bridges.     

Experimental study on double composite action in the negative flexural region of two-span continuous composite box girder

In the negative flexural region of continuous composite girder, cracking of concrete slab results in a reduction in the sectional stiffness and may affect the durability of reinforcement. Double composite action defined as attaching additional concrete to steel bottom flange to improve local buckling strength can be a way to increase the sectional stiffness. It has many advantages for construction while disadvantages also exist. In this case, two continuous composite girders, both of which had two 9 m long spans with 300 mm extension at each edge support and were 0.55 m high, were designed to study the mechanical properties in concrete crack, formation of sectional plastic hinge, load-carrying capacity, etc. One was a conventional composite girder named CCG and the other one was designed with double composite action in the negative flexural region named DCG. Moreover, evaluations of concrete crack width, based on different design codes, and cracking moment were compared with test results and agreed with each other. It indicated double composite action made concrete crack development slower in service load stage. The evaluation of sectional bending-carrying capacity of CCG in the negative flexural region based on the mechanical model with full plastic section of Euro Code 4 and an analogous method was found to evaluate that of DCG. The evaluation results coincided with test results proved the summation which can be drawn from test results.     

钢板-混凝土空心组合板受力性能与设计方法研究

钢板-混凝土空心组合板是一种新型组合板形式,由下部平钢板、纵向开孔钢板(肋板)、矩形空心内模和上部混凝土面层组合而成。该新型板由于使用空心内模,具有自重轻,隔声,节能的优点,并且具有施工免模板、免临时支撑等特点,具有广泛的应用前景。为研究组合板静力受剪和受弯性能,对6块钢板-混凝土空心组合板试件进行了两点对称集中加载静力试验研究。研究组合板随名义剪跨比变化的破坏形态及受力行为的变化规律。通过试验研究,考察6个组合板试件的破坏形态、钢板与混凝土应变发展情况、裂缝发展情况及组合板承载能力。结果表明:空心组合板具有良好的受力性能,钢板与混凝土组合良好,界面之间无明显滑移;组合板受弯承载能力计算可以采用平截面假定,底部钢板强度可以得到充分发挥;组合板具有较高的受弯承载能力和刚度,并具有良好延性。根据试验研究结果,建立钢板-混凝土组合板受弯承载能力计算公式,为该新型组合板在工程实践中的推广应用提供技术依据和理论支持。     

带钢板-混凝土组合桥面板的组合梁疲劳性能试验研究

为研究带钢板-混凝土组合桥面板的组合梁在疲劳荷载下的受力性能,对2个试件进行静力试验研究,并对6个试件进行等幅疲劳试验研究。疲劳试验试件按承受正弯矩和承受负弯矩两组类型试件分别考虑,在各组试件中均主要考察疲劳荷载上、下限值及疲劳荷载幅值等因素对带钢板-混凝土组合桥面板组合梁的疲劳破坏模式及疲劳累积损伤的影响。疲劳试验过程中对组合梁试件在各主要循环加载次数下的动挠度、残余挠度、混凝土应变、底部钢板应变、试件钢梁应变及试件受弯刚度进行试验测量和分析。疲劳试验结果表明:正弯矩组合梁试件的疲劳破坏形态为组合梁底部钢梁疲劳断裂破坏,进而受压区混凝土压碎破坏,试件疲劳寿命主要与试件疲劳应力幅有直接关系,而疲劳荷载的上、下限值对疲劳寿命影响较小;负弯矩组合梁试件在200万次循环荷载下均未发生疲劳破坏且仍具有较高承载能力和刚度,表现出了良好疲劳性能。研究成果可为该类型组合梁设计应用提供依据。     

装配式内置双钢套管混凝土组合#br# 剪力墙的抗震性能试验研究

提出一种可适用于高层建筑的装配式内置双钢套管混凝土组合剪力墙,通过6个剪跨比为2.86的两层组合剪力墙试件的拟静力抗震试验,考察试件的装配整体性,研究组合墙体的破坏机理和抗震性能。结果表明：试件的破坏形态整体为弯剪复合破坏,特征表现为约束边缘构件的竖向钢筋和外钢管受拉屈服、混凝土压溃、外钢管有压鼓曲,剪切斜裂缝明显;连接坐浆层和预制墙体均有裂缝发展和分布,两者之间无相对错动;试件滞回曲线有捏拢现象,峰值荷载后骨架曲线有平缓承载力下降段,塑性变形和延性能力良好,表现出良好的装配整体性;螺栓径向固结内、外钢管可实现钢套管间的约束和连接;平面外荷载偏心对滞回性能有重要影响,较大偏压矩试件仍有较好的变形和延性能力,内置钢管混凝土芯柱发挥了可靠连接作用,可提高装配墙体的面外压弯能力;钢管混凝土截面含量比小的试件有较大的位移延性,预制组合墙的参数组合还需优化。     

Analysis of deflections of composite slabs with profiled sheeting up to the ultimate moment

This paper deals with an investigation of the deflections of composite slabs. The deflection of composite slabs depends directly on the shear stiffness of the connection between profiled steel sheeting and concrete. A method for calculating deflections of slabs is presented in this paper. This method is based on a theory of built-up bars, which allows one to take into account directly the shear stiffness of the connection. Influences on the stiffness of the structure of normal cracks in the concrete layer and plastic deformations of concrete that has been subjected to compression are also taken into account in the analysis method. The method gives one an opportunity to assess variations of these factors at all stages of the slab’s behaviour from the start of loading up to the ultimate moment. Results of the experimental investigations of a connection (contact) between steel profiled sheeting (Holorib type) and concrete are presented in this paper. In the results of these investigations, three stages of behaviour of the contact are distinguished. A connection shear characteristic is determined for each stage, which is used for calculating the deflection of the slab.Experimental investigations were performed on deflections of composite slabs with a Holorib type of profiled sheeting. Variations in experimental deflections of slabs were explored from the beginning of loading up to the ultimate moment.Theoretical calculations of deflections for the experimental slabs were made. Calculations were performed according to the method proposed by the authors. A comparison of experimental and theoretical values of deflections revealed that agreement between these values was sufficiently good at all stages of the slab’s behaviour.     

Experimental study on semi-rigid composite joints with steel beams and precast hollowcore slabs

The concept of semi-rigid composite connection has been widely researched in the past; however, most of the researches are limited to composite joints with metal deck flooring and solid concrete slabs. Composite construction incorporating precast concrete hollowcore slabs (HCU) is a recently developed composite floor system for buildings. The research on the structural behaviour of the semi-rigid composite joints with HCU is new and without any previous experimental database. In this paper, eight full-scale tests of beam-to-column semi-rigid composite joints with steel beams and precast hollowcore slabs are reported. The variables are stud spacing, degree of the shear connections, area of the longitudinal reinforcement and slab thickness. The test set-up and instrumentation is described in detail. The experimental behaviour is analysed and based on the test data the structural behaviour of these semi-rigid composite joints is discussed. Based on the experimental data, a simplified method to predict rotation and moment capacity for this type of composite connection is proposed.     

压型钢板-混凝土组合楼板的承载能力研究

压型钢板-混凝土组合楼板的承载能力受楼板叠合面的纵向抗剪能力控制。本文通过3组组合楼板的荷载试验,研究了单跨简支组合楼板和两跨连续组合楼板的极限抗剪和抗弯性能。试验结果表明:组合楼板的极限承载能力受叠合面的纵向抗剪能力控制;与简支组合楼板相比,连续组合楼板承载能力有明显提高,跨中挠度显著减小,端部支座剪力出现滑移时与简支板端部剪力值相近,显示了连续组合板的端部滑移与剪力的关系与简支板的情况相似。但与简支组合板不同的是,连续组合板端部出现滑移后,其极限承载能力明显高于相同跨度简支板极限承载力。根据试验结果,得到了组合楼板叠合面纵向抗剪能力的计算公式。在组合楼板的承载力设计中,应对支座端部的竖向剪力进行叠合面的纵向抗剪能力验算,文中提出了连续组合楼板的承载力计算方法。