预应力混凝土T形梁设计(计算示例).

预应力混凝土T形梁设计计算示例

预应力混凝土T形梁设计计算示例 ----------------------------------------------------------------------------------------- 1

1 设计资料及构造布置--------------------------------------------------------------------------------------------------- 3

1.1桥梁跨径及桥宽-------------------------------------------------------------------------------------------------------- 3

1.2 设计荷载 ---------------------------------------------------------------------------------------------------------- 3

1.3 材料及施工工艺------------------------------------------------------------------------------------------------- 3

1.4 设计依据 ---------------------------------------------------------------------------------------------------------- 3

1.5 横截面布置------------------------------------------------------------------------------------------------------- 3

1.6 横截面沿跨长的变化 ------------------------------------------------------------------------------------------ 5

1.7 横隔梁的设置---------------------------------------------------------------------------------------------------- 5

2 主梁内力计算 ------------------------------------------------------------------------------------------------------------ 5

2.1 恒载计算 ---------------------------------------------------------------------------------------------------------- 5

2.2可变作用计算------------------------------------------------------------------------------------------------ 6

2.2.1冲击系数和车道折减系数--------------------------------------------------------------------------- 6

2.2.2.计算主梁的荷载横向分布系数-------------------------------------------------------------------- 7

2.2.

3. 车道荷载取值 ---------------------------------------------------------------------------------------10

2.2.4.计算可变作用效应 ---------------------------------------------------------------------------------- 11

2.3 主梁作用效应组合 --------------------------------------------------------------------------------------------14

3 预应力钢束的估算及其布置 ----------------------------------------------------------------------------------------15

3.1跨中截面钢束的估算和确定--------------------------------------------------------------------------------15

3.2预应力钢束的布置 --------------------------------------------------------------------------------------------16

4．计算主梁截面几何特征 ---------------------------------------------------------------------------------------------19

4.1截面面积及惯矩计算 --------------------------------------------------------------- 错误！未定义书签。

4.1.1净截面几何特征计算--------------------------------------------------------------------------------19

4.1.2换算截面几何特征计算-----------------------------------------------------------------------------21

4.1.3有效分布宽度内截面几何特征计算 -------------------------------------------------------------21

4.1.4截面静矩计算 -----------------------------------------------------------------------------------------22

5.主梁截面承载力与应力验算 -----------------------------------------------------------------------------------------26

5.1正截面承载力验算 --------------------------------------------------------------------------------------------26

5.1.1确定混凝土受压区高度：--------------------------------------------------------------------------26

5.1.2验算正截面承载力：--------------------------------------------------------------------------------27

5.1.3验算最小配筋率----------------------------------------------------------------------------------------27

5.2. 斜截面承载力验算 ------------------------------------------------------------------------------------------28

5.2.1斜截面抗剪承载力验算： ---------------------------------------------------------------------------28

5.2.2箍筋计算： ----------------------------------------------------------------------------------------------29

5.2.3抗剪承载力计算----------------------------------------------------------------------------------------30

5.3持久状况正常使用极限状态抗裂验算 --------------------------------------------------------------------31

5.3.1．正截面抗裂验算------------------------------------------------------------------------------------31

5.3.2．斜截面抗裂验算------------------------------------------------------------------------------------32

5.4持久状况构件的应力验算------------------------------------------------------------------------------------37

5.4.1．正截面混凝土压应力验算 -----------------------------------------------------------------------37

5.4.2．预应力筋拉应力验算------------------------------------------------------------------------------38

5.4.3．截面混凝土主压应力验算 -----------------------------------------------------------------------39