公路工程

为在一定程度上填补钢-混混合梁桥主梁算法优化方面的空白，探寻比传统桥梁设计方法更为精确和高效的参数分析及优化设计方法。依托云南某连续刚构桥，基于正交试验及Midas/Civil有限元试验设计的混合梁桥，以关键截面内力、位移及主梁自重为优化指标，选取钢箱梁长度、梁高比、梁底抛物线幂次、墩双肢间距为因素并各设置5个水平，构建L₂₅(5⁴)的正交表对主梁参数进行优化。通过单指标极值分析表明：钢箱梁长度在45～60 m、梁高比在2.5～3.0、梁底抛物线幂次在1.8～2.0次方、墩双肢间距在5～7 m内为宜；通过多指标综合分析得出最优参数组合：钢箱梁长度取53 m,梁高比取2.857,梁底抛物线幂次取1.7次方，墩双肢间距取7 m,且影响因素依次排序为钢箱梁长度→梁高比→梁底抛物线幂次→墩双肢间距。基于熵权法评估体系，经正交试验优化后的桥梁性能在挠度、应力及自重方面均得到整体改善，其中又以主梁中跨钢混结合梁段所属截面优化效果最为显著；客观权重量化分析结果表明：优化前的钢-混结构得分0.441,优化后的钢-混结构得分0.712,涨幅高达61.45%,证明优化后的钢-混结构综合性能更为出色且提升效果可观，而所采取的正交试验优化设计行之有效且可信度较高。

To some extent fill the gap in algorithmic optimization of main beams for steel-concrete hybrid beam bridges, and to explore parameter analysis and optimization design methods that are more accurate and efficient that traditional bridge design approaches. Relying on a continuous rigid frame bridge in Yunnan, based on the hybrid beam bridge designed by orthogonal test and Midas/Civil finite element trial, with the internal forces and displacement of key sections, as well as the main beam weight, serving as the optimization indexes, the length of steel box beam, beam height ratio, parabolic power of beam bottom, and double-limb pier spacing were selected as the factors, each set with five levels, to construct an L₂₅(5⁴) orthogonal table for optimizing the parameters of the main beam. Through single-index extreme value analysis, it is shown that: the length of steel box beam should be in the range of 45～60 m, beam height ratio in 2.5～3.0, parabolic power of beam bottom in 1.8～2.0,and double limb pier spacing in 5～7 m; through multi-index comprehensive analysis, the optimal parameter combination is obtained: steel box beam length of 53 m, beam height ratio of 2.857, parabolic power of beam bottom of 1.7, and double-limb pier spacing of 7 m, with the order of influence factors being: steel box beam length →beam height ratio→parabolic power of beam bottom→double-limb pier spacing. Based on the entropy weight method evaluation system, the performance of the bridge after orthogonal test optimization has been comprehensively improved in terms of deflection, stress, and self-weight, with the most significant optimization effect observed in the sections of the steel-concrete composite segment of the mid-span main beam; objective weight quantitative analysis results show that: the score of the steel-concrete structure before optimization is 0.441, and after optimization it is is 0.712, representing an increase of 61.45%, demonstrating that the optimized steel-concrete structure has superior comprehensive performance with considerable improvement, and the adopted orthogonal test optimization design is effective and highly reliable.