摘 要

现如今，随着桥梁的设计水平与施工技术的不断提高，连续梁桥的跨径越来越大，然而数据反映，由于跨径的增加，梁体开裂和跨中过度下挠的问题日益突出。而超高性能混凝土UHPC因其优良的力学性能引起了广泛关注，这种材料的抗压、抗拉性能和耐久性能较传统混凝土均有显著的提升，能够很好地解决主梁开裂和挠度过大的问题，目前在世界上已得到广泛的应用。

本设计以广东省英德市省道S292线北江四桥为工程背景，根据任务书所给地质资料，初步拟定出三个可行比选方案：UHPC新型连续梁桥、普通预应力混凝土连续梁桥、预应力混凝土斜拉桥，从安全、经济、环保、美观等多方面进行综合比选，最后选取UHPC新型连续梁桥作为设计推荐方案。

本次设计先介绍了UHPC材料以及UHPC密集横隔板薄壁箱梁结构，在方案比选后，详细说明了孔径布置，拟定主梁上、下部结构尺寸，确定桥面铺装层，最后通过有限元软件进行结构验算。

本设计利用有限元软件Midas Civil进行结构分析计算，根据桥梁设计的横截面尺寸、桥跨布置建立桥梁模型，然后施加荷载，计算各阶段主梁恒载内力和活载内力；根据抗裂性要求，结合Midas软件估算并布置预应力筋，计算预应力由于管道摩擦、锚具变形等引起的预应力损失；再根据内力组合原则，计算两种极限状态下的作用效应组合，后进行主梁截面验算，主要包括正截面抗弯验算、斜截面抗剪验算、抗裂验算、挠度验算以及持久和短暂状况构件应力验算；最后进行行车道板应力验算。

关键词：超高性能混凝土（UHPC）；预应力混凝土；连续梁桥；结构分析

Abstract

Nowadays, with the continuous improvement of the design level and construction technology of bridges, the span of continuous beam bridges is getting larger and larger. However, data shows that due to the increase in the span, the problem of cracking of the main beam and excessive deflection of the midspan is becoming increasingly prominent. Therefore Ultra-High Performance Concrete (UHPC) has attracted wide attention because of its excellent mechanical properties. The compressive strength, tensile strength and durability of this material are significantly higher than those of conventional concrete, which can solve the problems of cracking and deflection of the main beam. Currently UHPC has been widely used in the world.

This design is based on the Beijiang Fourth Bridge of the S292 line of Yingde City, Guangdong Province. According to the geological conditions of the bridge site, three alternatives are proposed:Ultra-High Performance Concrete(UHPC) continuous beam bridge with novel prestressed box-girder, ordinary prestressed concrete continuous beam bridge and prestressed concrete cable-stayed bridge. Through the comprehensive comparison of safety, economy, environmental protection, aesthetics, and other aspects, the UHPC continuous beam bridge was selected as the recommended design scheme.

In this design, Ultra-High Performance Concrete material and UHPC novel prestressed box-girder are first introduced. After determining the optimal scheme in the design, the layout of the span is explained in detail. Then the size of the super and substructure of the main beam is drawn up, and the deck pavement is determined. Finally, the structural calculation is performed by the finite element software.

The design uses finite element software Midas Civil for structural analysis and calculation. According to the cross-sectional dimensions of the bridge design and the bridge span layout, a bridge model is established. Then apply load to calculate the dead load internal force and live load internal force of the main beam at each stage. According to the requirements of crack resistance, Midas software is used to estimate and arrange the prestressed tendons. Then the prestress loss caused by pipeline friction, anchorage deformation and other factors is calculated. Based on the principle of internal force combination, the load effect combinations under two limit states are calculated. In addition, cross section checking of the main girder are carried out, which mainly includes the checking of the bending resistance of the cross section, the checking of shear carrying capacity, the checking of crack resistance, the checking of deflection, and the checking of stress in the permanent and transient conditions. Last, the checking of stress of bridge deck is completed.

Key Words: ultra-high performance concrete（UHPC）；prestressed concrete；continuous beam bridge；structural analysis

目 录

第1章 绪论 1

1.1 超高性能混凝土UHPC概述 1

1.2 大跨径UHPC新型梁桥结构 1

1.3 本文主要研究内容 2

第2章 设计基本情况说明 3

2.1 设计标准 3

2.2 地质条件 3

2.3 主要材料 3

2.4 主要规范 4

第3章 桥型方案比选 5

3.1 方案比选的意义及原则 5

3.2 初选方案 6

3.3 设计方案一：UHPC新型预应力混凝土连续梁桥 6

3.4 设计方案二：普通预应力混凝土连续梁桥 11

3.5 设计方案三：混凝土斜拉桥 15

3.6 方案比选 20

第4章 UHPC连续梁桥总体布置 22

4.1 桥型布置 22

4.1.1 孔径布置 22

4.1.2 桥梁截面形式 22

4.1.3 桥面铺装 23

4.1.4 桥梁下部结构 24

4.1.5 使用材料 24

第5章 Midas计算模型的建立 26

5.1 材料特性 26

5.2 全桥结构单元的划分 26

5.2.1 划分单元原则 26

5.2.2 桥梁具体单元划分 26

5.3 荷载的定义 27

5.4 全桥施工节段划分 27

5.4.1 桥梁划分施工阶段原则 27

5.4.2 施工阶段划分 27

第6章 主梁内力计算 30

6.1 恒载内力计算 30

6.1.1 自重及二期恒载 30

6.1.2 悬臂拼装阶段内力 30

6.1.3 边跨合龙阶段内力 31

6.1.4 中跨合龙阶段内力 31

6.1.5 桥面铺装阶段内力 32

6.1.6 支座位移引起的内力 32

6.2 活载内力计算 33

6.2.1 自振频率及横向分布系数 33

6.2.2 移动荷载引起的内力 34

6.3 温度荷载引起内力 35

第7章 预应力钢束的估算与布置 37

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