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对混凝土箱梁墩顶横隔梁的拉压杆模型构形及其配筋设计方法进行了研究。首先讨论横隔梁力学边界条件的合理简化,提出了等效计算图式。根据深梁典型拉压杆模型并结合荷载传递路径的分析,给出了实心及开洞两种横隔梁的拉压杆模型。进一步研究揭示了该区域拉压杆模型构形有以下特点:对于高宽比为0.5―1.2的双支承横隔梁,高宽比及支承间距决定了模型中水平方向拉压杆间力臂长度及斜压杆倾角;对于高宽比为1.2―2的双支承横隔梁,模型可由双支承典型深梁及小高宽比双支承横隔梁模型组合而成,且构形不再受支承间距的影响;此外,洞口大小及位置会改变荷载传递路径,从而也影响到模型中斜压杆的倾角。以该文提出的横隔梁拉压杆模型为基础,并结合美国AASHTO公路桥梁设计规范,给出了墩顶横隔梁配筋设计方法。设计示例表明该方法具有良好的实用性,可供工程设计参考。
The tension and compression bar model of the diaphragm of concrete box girder piers and its reinforcement design method are studied. First of all, a reasonable simplification of the mechanical boundary conditions of the diaphragm is discussed, and an equivalent calculation scheme is proposed. According to the model of typical tension and compression beam of deep beam and the analysis of load transfer path, the tension and compression beam model of two types of beams with solid and open holes is given. Further studies revealed the following characteristics of the tension and compression rod model in this region: For double-support beams with aspect ratios of 0.5-1.2, the aspect ratio and the spacing of the support determines the length of the arm in the model And the inclination angle of bar; for the double-support beam with aspect ratio of 1.2-2, the model can be composed of double-supported typical deep beam and small aspect ratio double-supported beam model, and the configuration is no longer affected by the bearing spacing In addition, the size and location of the hole will change the load transfer path, which will also affect the inclination of the bar in the model. Based on the model of transversal beam tension-compression bar proposed by this paper, and combining with the design code of AASHTO highway bridge in the United States, the design method of the diaphragm of pier top diaphragm is given. The design example shows that the method has good practicability and can be used as reference for engineering design.