均布荷载作用下等截面连续梁最佳支座布置研究及工程应用

Optimal Support Arrangements for Continuous Beams with a Uniform Cross Section Subjected to Uniformly Distributed Loads and Its Application

均布荷载作用下等截面连续梁,如何通过改变支座间距使梁内弯矩绝对值最小,分析这一问题在工程实践中有重要意义。定性分析可知连续梁两端悬挑一定长度可以减小边跨跨中弯矩;基于力法的定量分析得到了1~7跨连续梁在三种支座布置条件下的最优方案:带悬挑最佳、带悬挑等跨度最佳及无悬挑最佳;通过对比,当跨数≥5时,带悬挑最佳支座和带悬挑等跨度最佳支座布置时梁内最大弯矩相差较小,此时最佳支座布置方案可近似采用带悬挑等跨度布置方案;进一步分析可得到带悬挑等跨度连续梁的支座间距统计公式,可用于带悬挑等间距多跨(跨数≥2)连续梁的支座布置。最后将带悬挑连续梁及无悬挑连续梁最佳支座布置应用于光伏支架檩条和连续梁桥的支座布置分析中,对比表明:采用优化布置支座节约了8.9%的光伏支架檩条量钢量,优化布置的连续梁桥相比传统布置,梁内最大弯矩减小了约16.8%。

Continuous beam with a uniform cross section subjected to uniformly distributed loads is widely used in engineering.It is of great importance to study the support arrangements because proper support placements can decrease beam moment and thus reduce material.Based on qualitative calculation,beam with overhang will reduce moment of the first midspan.In this paper,continuous beams with 1 to 7 spans are studied.Arrangements of beam support are optimized under three conditions:beams with overhang,beams with overhang and equal spans and beam without overhang.The study indicates that there is little difference in moment between optimized span and equal span for continuous beam with overhang when span number N≥5.The empirical formula of support placements for beam with overhang and equal span is deduced and is applicable for beams with span number N≥2.Then,the optimized continuous beam is applied in the design of PV supporting purlin and continuous bridge.Comparing with traditional support placements,it is demonstrated in the example that optimized beam can reduce 8.9% steel purlin consumption and decrease 16.8% moment in continuous bridge.