摘要
本桥位于云南昭通市钟鸣至彝良县三级公路K2+963处，桥梁平面线为直线，与水流方向正交，桥纵向坡度为0%，桥面横坡采用2.5%的双向横坡。
根据所给资料，拟定了预应力混凝土简支T形梁桥、预应力混凝土连续T形梁桥、预应力混凝土连续小箱梁桥三个桥型方案。通过方案比选，推荐方案为T形连续梁桥，孔径布置3×30m，桥梁全长103.85m。桥墩采用钢筋混凝土柱式桥墩，采用刚性扩大基础，桥台采用U型桥台。
上部结构的设计与计算，进行了结构细部尺寸拟定、静活载内力计算、配筋设计及控制截面强度、应力验算，活载变形验算等。经分析比较及验算表明该设计计算方法正确，内力分布合理，符合设计规范的要求。
下部结构计算，计算由上部荷载到桥台的台帽的内力。最后，进行下部结构验算以及地基承载力验算。
关键词：预应力、连续梁桥、柱式桥墩、刚性扩大基础
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Abstract
The bridge is located in zhongmingluoze river of zhongming to yiliang yunan province highway K2+963.Bridge horizontal alignment is the straight-line and it is orthogonal to the flow direction. Bridge vertical gradient is 0%. The bridge cross using a 2.5% slope.
According to the given data, three bridge options are developed.The first program is the prestressed concrete simply supported bridge, the second program is the prestressed concrete continuous girder bridge, the third program is the prestressed concrete
continuous small scale box girder bridge. Through the
comparison, the second program is recommended to be chose,which the total length is 103.85metes and
the aperture aperture layout：30+30+30meters. The bridge use column bridge pier .according to bearing layer of foundation, bridge use the expansion of pile. The abutment is U-abutment abutment.
In the
superstructures，through drawing up of structure’s dimension, internal force
calculation of dead and living load, prestressed steel design, hypoforce calculation, assessment of prestressing loss, checking computation of key section intension, stress, living load distortion, The conclusion can be drawn that the design is up to the design codes for
bridge.
In the substructure，the load, which is transfered from the superstructures ,are calculated. Finally, the bearing capacity of substructure and the ground also be checked.
Key Words:P restress force;Continuous girder bridge;Columnar pier; Rigid spread foundation
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毕业设计说明书
目 录
第一章 桥型方案比选 .............................................................................................................. 1
1.1 设计桥型的确定 ......................................................................................................... 1 1.2 设计方案比较 ............................................................................................................. 2 第二章 推荐方案尺寸拟 .......................................................................................................... 3
2.1 方案简介 ..................................................................................................................... 3 2.2截面细部尺寸的拟定 .................................................................................................. 3
2.1.1 T形梁的尺寸拟定............................................................................................ 3 2.1.2 横隔梁尺寸拟定 .............................................................................................. 3 2.3 桥面铺装 ..................................................................................................................... 4 2.4 本桥的主要材料 ......................................................................................................... 4 2.5 施工方式 ..................................................................................................................... 4 第三章 行车道板计算 .............................................................................................................. 5
3.1悬臂板荷载效应计算 .................................................................................................. 5
3.1.1永久作用 ........................................................................................................... 5 3.1.2可变作用 ........................................................................................................... 6 3.1.3承载能力极限状态作用基本组合 ................................................................... 6 3.2单向板荷载效应计算 .................................................................................................. 7
3.2.1永久作用 ........................................................................................................... 7 3.2.2可变作用产生的效应 ....................................................................................... 8 3.2.3作用效应组合 ................................................................................................... 9 3.3截面设计、配筋与承载能力验算 ............................................................................ 10 第四章 主梁内力计算 ............................................................................................................ 12
4.1 截面特性计算 ........................................................................................................... 12
4.1.1 梁截面的划分 ................................................................................................ 12 4.1.2 分块面积法计算预制中主梁跨中截面几何特性 ........................................ 12 4.1.3 跨中截面各单元截面特性 ............................................................................ 13 4.1.4 跨中截面的全截面几何特 ............................................................................ 14
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毕业设计说明书
4.1.5 主梁各截面几何特性 .................................................................................... 14 4.2 恒载内力计算 ........................................................................................................... 15
4.2.1 计算恒载集度 ................................................................................................ 15 4.2.2 内力计算 ........................................................................................................ 18 4.3 汽车荷载作用效 ....................................................................................................... 25
4.3.1 冲击系数和车道折减系数 ............................................................................ 25 4.3.2 主梁的荷载横向分布系数计算 .................................................................... 26 4.4 温度次内计算 ........................................................................................................... 33 4.5 内力组合 ................................................................................................................... 34
4.5.1 内力组合 ........................................................................................................ 34
第五章 预应力钢束估算及布置 ............................................................................................ 42
5.1 钢束估算 ................................................................................................................... 42
5.1.1 按正常使用极限状态的正截面抗裂验算要求估束 .................................... 42 5.1.2 按承载能力极限状态的应力要求计算 ........................................................ 45 5.1.3 估算结果 ........................................................................................................ 48 5.2 钢束布置 ................................................................................................................... 49
5.2.1 钢束各控制点位置的确定 ............................................................................ 49 5.2.2 钢束平弯段的位置及平弯角 ........................................................................ 51 5.2.3 主梁截面上缘配筋 ........................................................................................ 51 5.3 主梁净截面换算截面几何特性计算 ....................................................................... 51 第六章 预应力损失计算 ........................................................................................................ 58
6.1 基本原理 ................................................................................................................... 58 6.2 预应力损失计算 ....................................................................................................... 58
6.2.1 后张法由预应力钢筋与管道之间摩擦引起的应力损失 ............................ 58 6.2.2 后张法由锚具变形、钢筋回缩和接缝压缩引起的应力损失 .................... 61 6.2.3 后张法由混凝土弹性压缩引起的应力损失 ................................................ 65 6.2.4 后张法由钢筋松弛引起的预应力损失终极值 ............................................ 69 6.2.5 后张法由混凝土收缩、徐变引起的预应力损失值 .................................... 71 6.2.6 截面预应力损失合计和有效预应力 ............................................................ 73
第七章 预加力次内力计算及组合 ........................................................................................ 75
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毕业设计说明书
7.1 次内力计算 ............................................................................................................... 75 7.2 内力组合 ................................................................................................................... 76 第八章 主梁截面强度验算 .................................................................................................... 79
8.1 基本理论 ................................................................................................................... 79 8.2 计算公式 ................................................................................................................... 79 第九章 主梁抗裂验算 ............................................................................................................ 84
9.1 正截面抗裂验算 ....................................................................................................... 84 第十章 持久状况构件的应力验算 ........................................................................................ 88
10.1 正截面混凝土压应力验算 ..................................................................................... 88 10.2 预应力筋拉应力验算 ............................................................................................. 90 第十一章 短暂状况构件的应力验算 .................................................................................... 92
11.1 预加力阶段的应力验算 ......................................................................................... 92 11.2 吊装验算 ................................................................................................................. 93 第十二章 主梁变形验算 ........................................................................................................ 94
12.1 汽车荷载作用下主梁边跨和中跨的最大截面挠度计算 ..................................... 94
12.1.1 边跨最大挠度计算 ...................................................................................... 94 12.1.2 中跨最大挠度计算 ...................................................................................... 95 12.2 温度效应作用下主梁边跨和中跨的最大截面挠度值。 ..................................... 95 12.3 消除结构自重后长期挠度验 ................................................................................. 96 第十三章 桥台计算 ................................................................................................................ 98
13.1 桥台及基础构造和拟定尺寸 ................................................................................. 98 13.2 荷载计算 ................................................................................................................. 98
13.2.1 上部构造恒载反力及桥台台身、基础上土重力计算 .............................. 98 13.2.2 土压力计算 .................................................................................................. 99 13.2.3 支座活载反力计算 .................................................................................... 102 13.2.4 支座摩阻力计算 ........................................................................................ 103 13.3 按承载能力极限状态设计时效应组合 ............................................................... 103 13.4 地基承载力验算 ................................................................................................... 104
13.4.1 台前、台后填土对基底产生的附加应力 ................................................ 104 13.4.2 基底压应力计算 ........................................................................................ 105
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