高速铁路常用跨度32m预应力混凝土简支箱梁优化设计研究

Study on Optimal Design of Simply-supported Box Beam with 32 m Span in High-speed Railway

我国高速铁路桥梁以常用跨度32 m预应力混凝土简支梁桥为主,在充分吸收前期设计、工程实践和科研成果的基础上,对时速350 km和时速250 km系列的32 m跨度简支箱梁,从梁高、预应力体系、细部构造尺寸等方面进行优化设计研究。通过优化箱梁结构尺寸、应用高强度预应力钢绞线和大吨位锚具等方法,减小了箱梁的腹板厚度,减少了梁体的材料用量和梁体质量,同时也简化了箱梁的施工工序;对优化前后的简支箱梁进行车桥耦合计算及对比,在德国低干扰谱下,梁高3.0 m满足1.2倍设计速度的检算要求,梁高2.8 m满足1.1倍设计速度的检算要求;对不同梁高箱梁在设计时速400 km高速铁路下的适应性进行分析,仅3.0 m梁高方案可满足1.1倍设计速度的检算要求;开展经济性对比研究,一孔32 m简支箱梁优化后造价减少5万元左右,减少7.17%~7.46%,梁高2.8 m的造价略低于梁高3.0 m的造价。

China's high-speed railway bridges are mainly prestressed concrete simply-supported bridges with a span of 32 m.On the basis of fully absorbing previous designs,engineering practices and scientific research achievements,the optimal design of 32 m simply supported box beam for 350 km/h and 250 km/h is studied from the aspects of beam height,prestressing system and detail structure size.By optimizing the structural size of box beam,applying high-strength prestressed steel strand and large-tonnage anchorage,the web thickness of box beam is reduced,the material consumption and weight of box beam are cut down,and the construction process of box beam is simplified as well.The vehicle-bridge coupling calculation and comparison of the simply-supported box beam before and after optimization are carried out.In the low interference spectrum of Germany,the beam height of 3.0 m meets the checking requirement of 1.2 times the design speed,and the beam height of 2.8 m meets the checking requirement of 1.1 times the design speed.The adaptability of box beam with different beam heights for the design speed of 400 km/h high-speed railway is analyzed.Only the 3.0 m beam height scheme can meet the checking requirements of 1.1 times the design speed.A comparative study on economy is conducted.After optimization,the cost of a 32 m simply supported box beam is reduced by about 50,000 yuan,7.17%~7.46%reduction,and the cost of 2.8 m height beam is slightly lower than that of 3.0 m height beam.