基于AASHTO规范的预应力T形梁桥优化设计

Optimal Design of Prestressed T-beam Bridge Based on AASHTO Specification

依托孟加拉达卡-阿苏利亚高架快速路项目(DAEEP),根据AASHTO规范确定约束条件,考虑经济性指标,采用遗传算法对预应力混凝土T形梁桥进行优化计算,并应用Midas Civil建立有限元模型对优化前后设计方案进行校核对比。结果表明:主梁控制弯矩减小,边梁-中梁弯矩更加均匀合理,各项指标满足规范要求;不同跨径桥梁优化后,上部结构造价降低10.3%~14.5%,经济效益明显;T梁截面跨高比增大,其值在16.6~19.2之间,当跨径大于40m后,比值基本不变。DAEEP项目采用矮T梁方案是经济合理的,可为类似海外工程项目设计提供参考。

Based on the Dhaka-Ashulia elevated expressway project in Bangladesh an optimal design was presented for the prestressed concrete T-beam bridge by using genetic algorithm according to AASTHO specification which considered economic indicators.Meanwhile Midas Civil was applied to establish finite element model to check the design schemes.The optimization results showed that governing moment of beams are reduced and the moments of interior beams and exterior beams are more uniform.All the design indexes can meet the requirements of AASTHO specification.After optimization of bridges with different spans the cost of the superstructure is reduced by 10.3%~14.5%.The span-depth ratio increases and its value is between 16.6 and 19.2.The ratio is basically kept the same when the span is more than 40m.The lower T-beam scheme is appropriate and economic for the DAEEP project.It can provide reference for the design of similar overseas projects.