预应力混凝土连续梁桥毕业设计

摘 要

本设计所设计的是预应力混凝土连续梁桥的设计，该桥位于宁夏王洼到原州区段，

为单线铁路桥梁，主要设计桥梁的上部结构，设计荷载采用中—活载。

本设计采用预应力混凝土连续梁桥，其孔径布置为48+80×2+48m，全长为256m，主梁采用变高度变截面的单箱单室箱型截面，施工方法采用对称悬臂施工法。本设计使用midas 软件分析，考虑施工过程体系转换和混凝土收缩徐变因素进行恒载内力计算。计算各控制截面内力影响线，并按最不利情况进行加载，求得活载内力包络图。定义基础沉降组，按最不利组合求得基础沉降引起的最不利内力。依据规范选取截面梯度温差模式，并计算温差引起的结构内力。分别按主力组合和主力附加力进行荷载组合，并得到结构组合内力包络图。根据各控制截面内力进行了估束和配筋计算，并绘制了梁体钢束布置图。最后，对各控制截面进行了强度、抗裂性、应力和变形验算，各项检算均满足规范对全预应力结构的要求。

关键词：连续梁； 内力计算； 预应力混凝土； 检算；

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Abstract

What I designed at the undergraduate design is a prestressed concrete continuous beam bridge .It lies in Wangwa to Yuanzhou， Ningxia province .It is a single line railway .I mainly designed the superstructure of the bridge. The load for design is the “zhonghuo”load. I adopt a prestressed concrete continuous beam bridge with four spans of 48+80×2+48m ，Its total span is 256m . First the size of girder is determined； highly variable for the variable beam cross-section single-Box Single girder and balanced cantilever construction is used . Then the Midas program is used to calculate the internal force caused by dead load of the first stage ，considering the construction stage ， after imposing the second stage dead load on the complete system . The internal force of the stage is calculated . The internal force influence lines of the control section is calculated ， then the live load is imposed according to the most adverse circumstances to get the Force Envelope .The program is used to determine the most adverse circumstances and calculate the internal force after defining the settlement groups of the basis.The temperature load is imposed consider the shrinkage and creep of the concrete . Then combination of load effects is made acoording to the Main force combination and the Main force plus additional force combination .According to the internal force of control sections ， the number of per-stressing steel stands is estimated and the per-stressing steel stands are arranged in the bridge . Finally a check is made of the bearing capacity ， the ability to resist crack and the sterss of the control section ， all the requirements can be met .

Internal force calculation；Checking Keywords: Continuous beam； Prestressed concrete ；computation；

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目录

第一章 绪论 ........................................................................................................................ 1 第二章 结构尺寸拟定 ............................................................................................................ 2

第一节 总体布置 ............................................................................................................ 2 第二节 细部尺寸拟定 ...................................................................................................... 2

一、主梁梁高 ............................................................................................................ 2 二、截面尺寸 ............................................................................................................ 2 三、各截面细部尺寸 ................................................................................................ 3 第三节 本桥主要材料 .................................................................................................... 3

一、混凝土： ............................................................................................................ 3 二、预应力钢绞线： ................................................................................................ 4 三、箍筋： ................................................................................................................ 4 四、应力管道： ........................................................................................................ 4 第四节 施工方法 .............................................................................................................. 4

一、桥墩与零号块施工 ............................................................................................ 4 二、悬臂施工到最大悬臂状态 ................................................................................ 4 三、边跨膺架现浇 .................................................................................................... 4 四、边跨合拢 ............................................................................................................ 5 五、中跨跨中合拢 .................................................................................................... 5 六、桥面铺装 ............................................................................................................ 5

第三章 预应力混凝土连续梁桥内力计算 ............................................................................ 5

第一节 计算模型建立 .................................................................................................... 5 第二节 毛截面几何特性计算 ........................................................................................ 6 第三节 恒载内力计算 .................................................................................................... 7

一、计算方法 ............................................................................................................ 7 二、控制截面选择 .................................................................................................... 8 三、恒载取值 ............................................................................................................ 8 四、各施工阶段的内力计算 .................................................................................... 8 五、控制截面恒载内力 ............................................................................................ 9 第四节 活载内力计算 .................................................................................................. 10

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一、活载动力系数的计算 ...................................................................................... 10 二、各控制截面在最不利活载作用下的弯矩影响线及加载 .............................. 11 三、各控制截面在最不利活载作用下的剪力影响线及加载 .............................. 16 四、控制截面的活载内力 ...................................................................................... 19 第五节 温度及支座沉降次内力计算 .......................................................................... 21

一、温度次内力计算 .............................................................................................. 21 二、支座沉降次内力 .............................................................................................. 22 第六节 主梁作用效应组合 .......................................................................................... 24

一、主力组合和主力加附加力组合下各控制截面的内力 .................................. 24 二、各截面在作用效应组合下弯矩包络图 .......................................................... 26 三、各截面在作用效应组合下剪力包络图 .......................................................... 27

第四章 配筋计算 .................................................................................................................. 27

第一节 钢束估算 .......................................................................................................... 27

一、估束方法 .......................................................................................................... 27 二、预应力筋估算 .................................................................................................. 30 第二节 预应力钢束布置 .............................................................................................. 34

一、布束原则 .......................................................................................................... 34 二、钢束的布置 ...................................................................................................... 34

第五章 检算 .......................................................................................................................... 38

第一节 抗裂性检算 ...................................................................................................... 38

一.正截面抗裂性检算 ............................................................................................. 38 二、斜截面抗裂性检算 .......................................................................................... 42 第二节 强度检核 ............................................................................................................ 45

一、受弯构件正截面强度检算 .............................................................................. 45 二、受弯构件斜截面承载能力计算 ...................................................................... 49 第三节 结构的应力检算 .............................................................................................. 50

一、压应力检算 ...................................................................................................... 50 二、拉应力检算 ...................................................................................................... 52 第四节 挠度验算 ...................................................................................................... 53 结论 .......................................................................................................................................... 54 致 谢 .................................................................................................................................. 55

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主要参考文献 .......................................................................................................................... 56 附录 .......................................................................................................................................... 57

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