摘要桥梁在设计过程中，上部结构（桥跨结构和支座系统）设计的合理性，影响整座桥梁的安全性、耐久性。通过一系列数据分析，对桥梁上部结构的一系列方案进行对比，选出最佳的上部结构设计方案，以达到满足交通需求、安全性且尽可能降低成本的目的。T型截面桥梁两肋处的混凝土很大程度上被挖空，桥体自重大幅减轻。混凝土本身抗压能力远远大于其抗拉能力，因此下部受拉钢筋提供了抗拉部分的绝大部分拉力，下部钢筋的受拉作用得到了充分地发挥。所以预应力T型梁混凝土用量少，桥体自重小，上部的压力又混凝土来承担，下部的拉力由预应力钢筋来承担，结构和受理性因此能都能达到理想的状态。由于其混凝土简支T梁桥有构造简单、施工方便、受力明确，能充分发挥材料特性等特点，已经成为了中小跨桥梁形式的首选方案。预应力混凝土T形梁是一种简支T形梁桥结构，具有构造简单，造价低廉，具有较好的跨越能力现在被越来越多的中型、大型桥梁桥梁作为首选方案，而且因为其便于维护，也成为了国防建设的首选桥梁。关键词：简支梁桥：预应力：方案比选：有限元模型。ABSTRACTThe rationality of superstructure (bridge span structure and support system)design affects the safety and durability of the whole bridge in the process of bridgedesign.A series of schemes of bridge superstructure are compared,whilst the bestsuperstructure design scheme is selected to meet the traffic demand,safety andeconomy through a series of data analysis.The concrete at the two ribs of T-section bridge is largely hollowed out,so theself weight of the bridge body is greatly reduced.The compressive capacity ofconcrete itself is far greater than its tensile capacity,so the tensile force of the tensilepart is provided by the lower tensile reinforcement.Therefore,the amount of concreteused in prestressed T-beam is small,the weight of bridge body is small too.Theupper pressure is borne by concrete,and the lower tension is borne by prestressedsteel,so the structure and acceptability can reach the ideal state.The concrete simplysupported T-section bridge has become the preferred option for medium and smallspan bridges,because of its simple structure,convenient construction,clear force andfull use of material characteristics.T-beam bridge structure include prestressedconcrete T-beam,which has good spanning ability,simple structure and low cost.Now,more and more medium-sized and large bridges are the first choice.Because itis easy to maintain,prestressed concrete T-beam has also become the first choice fornational defense construction.Keywords:Finite element model;Simply supported beam bridge;Prestressed;Scheme comparison.目录摘要ABSTRACT目录…1基本资料1.1地质条件1.2水文条件1.3气象条件1.4工程意义-22方案设计2.1方案比选2.2设计资料…2.3基本计算数据3尺寸设计…3.1主梁尺寸…-53.2截面的几何特性3.2.1跨中截面3.2.2支座截面.…3.2.3检验跨中截面效率指标p3.3预应力施加阶段的截面几何特性3.3.1跨中截面3.3.2支座截面-8-3.3.3检验跨中截面效率指标p4主梁内力计算4.1永久作用效应计算4.1.1永久作用集度.…4.1.2永久作用效应..-11-4.2可变作用效应计算(G-M法)4.2.1冲击系数和车道折减系数.-12-4.2.2主梁的荷载横向分布系数-12-