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 ----------------------------------------------------------------------------------------- 11 设计资料及构造布置--------------------------------------------------------------------------------------------------- 21.1桥梁跨径及桥宽-------------------------------------------------------------------------------------------------------- 31.2 设计荷载 ---------------------------------------------------------------------------------------------------------- 31.3 材料及施工工艺------------------------------------------------------------------------------------------------- 31.4 设计依据 ---------------------------------------------------------------------------------------------------------- 31.5 横截面布置------------------------------------------------------------------------------------------------------- 31.6 横截面沿跨长的变化 ------------------------------------------------------------------------------------------ 51.7 横隔梁的设置---------------------------------------------------------------------------------------------------- 52 主梁内力计算 ------------------------------------------------------------------------------------------------------------ 52.1 恒载计算 ---------------------------------------------------------------------------------------------------------- 52.2 可变作用计算------------------------------------------------------------------------------------------------ 62.2.1冲击系数和车道折减系数 ---------------------------------------------------------------------------- 62.2.2.计算主梁的荷载横向分布系数 ---------------------------------------------------------------------- 72.2.3. 车道荷载取值 ----------------------------------------------------------------------------------------- 112.2.4.计算可变作用效应------------------------------------------------------------------------------------- 112.3 主梁作用效应组合 --------------------------------------------------------------------------------------------143 预应力钢束的估算及其布置-----------------------------------------------------------------------------------------153.1跨中截面钢束的估算和确定---------------------------------------------------------------------------------153.2预应力钢束的布置 ---------------------------------------------------------------------------------------------164．计算主梁截面几何特征 ---------------------------------------------------------------------------------------------174.1截面面积及惯矩计算 ------------------------------------------------------------------------------------------174.1.1净截面几何特征计算----------------------------------------------------------------------------------174.1.2换算截面几何特征计算 ------------------------------------------------------------------------------184.1.3有效分布宽度内截面几何特征计算---------------------------------------------------------------194.1.4截面静矩计算-------------------------------------------------------------------------------------------205.主梁截面承载力与应力验算 -----------------------------------------------------------------------------------------245.1正截面承载力验算 ---------------------------------------------------------------------------------------------245.1.1确定混凝土受压区高度： ---------------------------------------------------------------------------245.1.2验算正截面承载力：----------------------------------------------------------------------------------255.1.3验算最小配筋率----------------------------------------------------------------------------------------255.2. 斜截面承载力验算--------------------------------------------------------------------------------------------265.2.1斜截面抗剪承载力验算： ---------------------------------------------------------------------------265.2.2箍筋计算： ----------------------------------------------------------------------------------------------275.2.3抗剪承载力计算----------------------------------------------------------------------------------------285.3持久状况正常使用极限状态抗裂验算 --------------------------------------------------------------------305.3.1．正截面抗裂验算 -------------------------------------------------------------------------------------305.3.2．斜截面抗裂验算 -------------------------------------------------------------------------------------305.4持久状况构件的应力验算------------------------------------------------------------------------------------355.4.1．正截面混凝土压应力验算-------------------------------------------------------------------------355.4.2．预应力筋拉应力验算 -------------------------------------------------------------------------------365.4.3．截面混凝土主压应力验算-------------------------------------------------------------------------375.5短暂状况构件的应力验算------------------------------------------------------------------------------------415.5.1．预加应力阶段的应力验算-------------------------------------------------------------------------416.主梁变形验算 ------------------------------------------------------------------------------------------------------------426.1荷载引起的跨中挠度 ------------------------------------------------------------------------------------------426.2结构刚度验算 ---------------------------------------------------------------------------------------------------431 设计资料及构造布置1.1桥梁跨径及桥宽后张预应力混凝土T形截面梁标准跨径：40m（墩中心距离）主梁全长：39.96m计算跨径：39.00m桥面净空：净-14+2×1.75m=17.5m1.2 设计荷载公路—II级，人群荷载3.0kN/m2，每侧人行栏、防撞栏的每延米重量分别为1.52kN/m和4.99kN/m。