摘 要

本桥为溧水经济技术开发区25号路三山湖主河道上的一座桥，初步设计为3×30m的预应力混凝土简支T形梁桥。该桥采用并列双幅布置，左、右幅桥等长。上部为装配式全预应力钢筋混凝土简支T梁。预制T梁高2.0m，主梁间距2.0m。为降低主梁高度，减少预应力引起的上拱度，后张法预应力混凝土T梁在设计荷载下按全预应力混凝土构件设计，主梁配筋采用预应力筋和非预应力筋混合配筋。锚具采用OVM15—6型锚具，锚具变形钢筋回缩按3mm计。预制件在张拉钢绞线时混凝土的强度应达到85%以上方可张拉。下部桥墩为钢筋混凝土圆形双柱式墩，墩柱直径1.0m；桥墩基础为钻孔灌注桩基础，桩径1.2m。桥墩盖梁为连续墩盖梁，按简支梁计算盖梁内力及墩柱顶竖向反力。桩基为单排桩形式，采用正循环泥浆护壁成孔。设计时应满足不同设计状况下规范规定的控制条件要求，例如承载力、抗裂性、变形及应力等要求。因此，预应力混凝土桥梁设计时，一般情况下，首先根据结构在正常使用极限状态要求正截面抗裂性或裂缝宽度限制确定预应力钢筋的数量，再由构件的承载力极限状态总要求确定普通钢筋的数量，然后进行持久状况截面承载力极限状态的计算，以及计算预应力钢筋的损失，最后进行应力验算、抗裂性验算、变形计算等，确定构件满足在承载力极限状态和正常使用极限状态下的各方面的各方面要求。

关键词：T梁；预应力；后张法；设计计算；钻孔灌注桩

Construction Drawing Design of Sanshan Lake Bridge

ABSTRACT

This study involves a 3×30m prestressed concrete simply supported T-beam bridge, designed for the Sanshan Lake of the No. 25 Road of the Lishui Economic and Technological Development Zone. The bridge adopts a parallel double layout, with left and right bridges as the same length. The upper part is a fabricated prestressed reinforced concrete T-beam with simply supported at the boundaries. The prefabricated T-beam is 2.0m in high and 2.0m in span. In order to reduce the height of the main beam and the camber caused by the pretension, the post-tensioned prestressed concrete T-beam is designed as a full prestressed concrete member under the design load. Both prestressed rebars and non-prestressed rebars are used as the main beam reinforcement. The anchors adopt OVM15-6 typed anchors, and the retracting of anchorage deformed bars is calculated by 3mm. The tensile strength of the prefabricated members should be 85% above the tensile strength of the preform before the tensioning construction. The bottom pier is a reinforced concrete circular double-column pier with a diameter of 1.0m; the pier foundation is a bored pile foundation with a diameter of 1.2m. The cover beam is a continuous beam, and the internal force of the cover beam and the vertical reaction force of the pier column top are calculated as simply supported beams. The pile foundation is designed as the form of a single row of piles. The design should meet the requirements of the controlling conditions, specified in the specifications, under different design conditions, such as the requirements of bearing capacity, crack resistance, deformation and stress. Therefore, during the designing, the number of prestressed steel bars is firstly determined according to the requirements of the normal use limit state of the structure in the normal section crack resistance or crack width, and then the total limit of the bearing capacity of the components is determined. After that, the number of steel rebars are dertermined through the calculation of the ultimate state of the bearing capacity of the cross-section under sustained conditions, and then the loss of prestressed steel rebars I dertermined. Finally, the stress checking, crack resistance checking, deformation calculation, etc., is performed to meet the limit state and normal use limit of the bearing capacity.

Key words: T-beam; prestress; post-tensioning; structural design; bored pile

目 录

第一章 设计资料 1

1.1 工程概况 1

1.2 设计依据 3

1.3 设计规范 4

1.4 设计标准 4

1.5 设计主要材料 4

1.6 基本计算数据表 5

第二章 桥型方案比选 6

2.1 方案对比 6

第三章 上部结构 7

3.1 设计参数与构造布置 7

3.1.1 设计参数 7

3.1.2 构造布置 7

3.2 行车道板计算 9

3.3 主梁内力计算 9

3.3.1 截面几何特性的计算 9

3.3.2 主梁恒载内力计算 9

3.3.3 荷载横向分布系数计算 11

3.3.4 计算活载内力 14

3.3.5 荷载内力计算 14

3.3.6 主梁荷载内力组合 22

3.4 主梁配筋计算（全预应力混凝土梁钢束布设和计算） 23

3.4.1 预应力钢筋的确定及布设 23

3.4.2 预应力钢筋的纵断面设计 24

3.4.3 普通钢筋数量的确定及布置 25

3.5 主梁截面几何特性计算 26

3.6 承载能力极限状态计算 28

3.6.1 正截面承载力计算 28

3.6.2 斜截面抗剪强度计算 29

3.7 预应力损失计算 31

3.8 正常使用极限状态计算 36

3.8.1 短暂状态应力验算 36

3.8.2 持久状况应力验算 37

3.8.3 混凝土主应力验算 38

3.9 预应力混凝土构件抗裂性验算 38

3.1 主梁变形（挠度）计算 42

3.10.1 使用阶段的挠度计算 42

3.10.2 预加力引起的反拱计算及预拱度的设置 43

3.11 横隔梁内力计算 43

3.11.1 确定中横隔梁上的计算荷载 43

3.11.2 横隔梁配筋 46

3.11.3 横隔梁裂缝验算 47

3.12 支座的设计计算 47

3.12.1 确定支座平面尺寸 48

3.12.2 确定支座厚度 49

3.12.3 支座偏转情况验算 49

第四章 下部结构 50

4.1 盖梁计算 50

4.1.1 荷载计算 50

4.1.2 双柱反力Gi计算 58

4.1.3 内力计算 59

4.2 截面配筋设计与承载力效核： 62

4.2.1 正截面抗弯承载力验算 62

4.2.2 斜截面抗剪承载能力验算 63

4.2.3 全梁承载力校核 65

4.3 桥墩墩柱计算 65

4.3.1 荷载计算 65

4.3.2 荷载组合 67

4.3.4 截面配筋计算及应力验算 68

4.4 钻孔灌注桩计算 70

4.4.1 荷载计算 70

4.4.2 桩长计算 72

4.4.3 桩的内力计算 74

4.4.4 桩身截面配筋及承载力验算 74

4.4.5 墩顶纵向水平位移验算 76

结论 78