带腹板开洞连续组合梁的受力性能及承载力研究

Continuous composite beam has been more and more widely used in the high-rise buildings. If web openings are provided on continuous composite beams, storey height of buildings can be reduced by letting pipes pass through web openings, and as the result that the overall cost can be reduced. However, the introduction of web openings can significantly affect beam behavior by decreasing stiffness and strength, and increasing deflection of composite beams. Where plastic hinge firstly emerges, in the intermediate support or in the corner of the opening region? What kind of types of plastic hinge will be formed (axial force hinge, shear force hinge or moment hinge)? Whether plastic analysis method of the moment redistribution or kinematic mechanism method can be used to calculate the ultimate strength of continuous composite beam with web openings? These questions remain unanswered at present. In addition to material strength reserve of section the structural strength reserve can be utilized by applying plastic analysis method. The main topic of the project is to investigate bearing behaviors of continuous composite beam with web openings and conditions for application of plastic analysis method. A lot of construction funds can be doubly saved by reducing of storey height of buildings and by using the material strength reserve with applying plastic analysis method. In addition from a scientific and theoretical sense, it will be an extension of application of plastic analysis method that if the plastic analysis method can be applied to continuous composite beam with web opening.

连续组合梁在高层建筑中运用越来越多，在连续组合梁的腹板上开洞，让水、暖、电管道穿过，可降低层高，节省大量的建设资金。但开洞后，梁的受力性能（刚度、强度、变形能力、破坏模式等）会受到很大影响，中间支座处是否还会先出现塑性铰？还是在洞口处先出现塑性铰以及会出现什么类型的塑性铰（轴力铰、剪力铰还是弯矩铰）？是否还可用弯矩调幅或塑性铰链法（机构法）等塑性分析方法来计算带腹板开洞的连续组合梁？这是目前尚待解决的问题。采用塑性分析除可挖掘截面的强度储备外，还可挖掘由于超静定而具有的结构强度储备。本课题的研究内容就是要弄清带腹板开洞连续组合梁的受力特性以及运用塑性分析的前提和条件，以实现双重（腹板开洞降低层高；塑性分析和计算以充分挖掘材料的塑性强度储备）节省大量建设资金的目的。另外，从科学和理论意义上看，若将塑性分析方法的运用范围从无腹板开洞扩大到带腹板开洞的连续组合梁，将是塑性理论的扩展和完善。

组合梁腹板上开洞可让各种管道设备管道穿过，降低层高，有好的经济效益，但会带来组合梁抗剪承载力的大大降低，为此本项目从实验、数值分析和理论计算三个方面进行了研究，取得了以下一些成果：.（1）弄醒了负弯矩区组合梁腹板开洞后的受力行为，如洞口区域截面不再符合平截面假定；破坏表现为洞口角部出现塑性铰，洞口区的部分栓钉连接件出现了拔脱现象；.（2）洞口上方混凝土翼板具有较大抗剪承载力，完全可以加以利用。另外增加纵向钢筋配筋率还可以进一步提高其变形能力；.（3）最有效的洞口加强方式与传统的有所不同，斜向设置最为有效。.（4）根据极限状态下洞口四个角截面上的塑性应力分布推导了次弯矩函数，建立了负弯矩作用下腹板开洞组合梁的极限承载力计算方法，该方法考虑了洞口上方混凝土板的抗剪作用，更接近实际情况，可改变目前缺乏工程实用计算方法的局面。