摘 要
清水河小桥是一座新建的预应力混凝土空心板简支梁桥,跨径为1x20m,设计交角90°。此种类型的桥是常见桥型,具有自重轻、工艺成熟、制作安装方便等优点。
本计算书的主要内容就是对该桥的上部结构及下部结构进行计算和验算。清水河小桥的横断面布置为:10m=0.5m(护栏) 9m(行车道) 0.5m(护栏)。根据这个断面形式,结合相关设计规范,初步拟定上部结构的设计思路和设计方法。本设计采用的是后张法预应力混凝土空心板,在设计的时候要满足梁的承载能力、抗裂性能、变形情况、应力状况等规范规定的梁在各种情况下的控制性要求。在荷载计算时要按不同的状况进行组合,根据结果配置预应力钢筋和普通钢筋,并进行预应力损失的计算和各种性能的验算。上部结构的最后还要进行铰缝、支座的计算和验算,所有的构件都要满足规范要求。下部结构按照任务书的要求,采用桩柱式基础、桩接盖梁桥台,桥台桩基采用Φ120cm钻孔灌注桩。结合上部结构荷载,桥墩立柱和桥台桩基按偏心受压计算,根据土层计算桩长;计算内力,设置钢筋并进行校核。
关键词:后张法;空心板梁;应力损失;偏心受压;钻孔灌注桩
Construction Design of Qingshui River Bridge
ABSTRACT
Qingshuihe Bridge is a newly built simply supported prestressed concrete hollow slab beam bridge with a span of 1 x 20m and a design angle of 90 degrees. This type of bridge is a common bridge type, which has the advantages of light weight, mature technology, easy fabrication and installation.
The main content of this calculation book is to calculate and check the upper and lower structures of the bridge. The cross section of Qingshui River Bridge is arranged as follows: 10m = 0.5m (guardrail) 9m (lane) 0.5m (guardrail). According to this section form and the relevant design specifications, the design ideas and methods of superstructure are preliminarily drawn up. This design adopts post-tensioned prestressed concrete hollow slab, which meets the control requirements of beams in various situations stipulated in the code of bearing capacity, crack resistance, deformation and stress conditions. When calculating the load, it should be combined according to different conditions. According to the results, the prestressing steel bar and ordinary steel bar should be allocated, and the calculation of prestressing loss and checking of various properties should be carried out. At the end of the superstructure, the calculation and checking of the hinges and supports are also carried out, and all the components should meet the requirements of the code. According to the requirements of the task book, the lower structure adopts pile-column foundation, pile-capped beam abutment, and the pile foundation of abutment adopts 120cm bored pile. Combined with the load of superstructure, the pile foundation of pier and abutment is calculated according to eccentric compression, the pile length is calculated according to soil layer, the internal force is calculated, the reinforcement bar is set up and checked.
Key word: Post tensioning method; Hollow slabs; Stress loss; Eccentric compression; Drilled grouting pile.
目 录
1 设计资料 1
1.1 任务概况 1
1.2 跨度和桥面宽度 1
1.3 技术标准 1
1.4 设计方案 1
1.5 主要材料 1
1.5.1 混凝土 1
1.5.2 钢材 2
1.5.3 伸缩缝 2
1.5.4 支座 2
1.5.5 桥台防护 2
1.6 设计要点 2
1.6.1 结构设计 2
1.6.2 设计参数 3
2 上部结构设计 4
2.1 空心板截面几何特性计算 5
2.1.1 截面面积 5
2.1.2 截面重心位置 5
2.1.3 空心板毛截面对其重心轴的惯性矩计算 5
2.2 作用效应计算 6
2.2.1 永久作用效应计算 6
2.2.2 可变作用效应计算 7
2.2.3 作用效应组合 14
2.3 预应力钢筋数量估算及布置 14
2.3.1 预应力钢筋数量的估算 14
2.3.2 预应力钢筋的布置 16
2.3.3 普通钢筋数量的估算及布置 16
2.4 换算截面几何特性计算 18
2.4.1 换算截面面积 18
2.4.2 换算截面重心位置 19
2.4.3 换算截面惯性矩 19
2.4.4 换算截面弹性抵抗矩 19
2.5 承载能力极限状态计算 20
2.5.1 跨中截面正截面抗弯承载力计算 20
2.5.2 斜截面抗剪承载力计算 21
2.6 预应力损失计算 22
2.6.1 摩擦损失 23
2.6.2 锚具变形、回缩引起的预应力损失 23
2.6.3 混凝土弹性压缩引起的预应力损失 23
2.6.4 钢筋松弛引起的应力损失 24
2.6.5 混凝土收缩和徐变引起的应力损失 24
2.6.6 预应力损失组合设计 27
2.7 正常使用极限状态计算 27
2.7.1 正截面抗裂性验算 27
2.7.2 斜截面抗裂性验算 31
2.8 变形验算 37
2.8.1 正常使用阶段挠度计算 37
2.8.2 预加应力引起的反拱计算及预拱度设置 38
2.9 应力验算 40
2.9.1 持久状况应力验算 40
2.9.2 短暂状况应力验算 45
2.10 最小配筋率校核 51
2.11 铰缝计算 52
2.11.1 铰缝剪力计算 52
2.11.2 铰缝抗剪强度验算 54
2.12 支座 55
2.12.1 选定支座的平面尺寸 55
2.12.2 确定支座厚度 56
2.12.3 验算支座的偏转情况 57
2.12.4 验算支座的抗滑稳定性 58
3 下部结构设计 59
3.1 桥梁下部结构设计资料 59
3.2 桥台盖梁计算 59
3.2.1 荷载计算 59
3.2.2 内力计算 68
3.2.3 截面配筋设计 70
3.2.4 承载力校核 72
3.3 桥台桩基计算 77
3.3.1 荷载计算 77
3.3.2 桩长计算 80
3.3.3 桩身内力计算 82
结 论 95
致 谢 96
参考文献 97
清水河小桥施工图设计计算书
1 设计资料
1.1 任务概况
清水河小桥上部结构的构造形式为后张法预应力混凝土空心板,桥面宽度:。下部结构采用桩柱式基础。设计荷载:公路-Ⅱ级;环境标准:I类环境。安全等级:二级。
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