镇江市某饭店于1974年施工,为高六层的混合结构,主楼梯采用预制预应力悬挑踏步板结构,踏步板断面尺寸如图1所示。踏步板压入墙体尺寸,底层为370毫米,二～六层为240毫米,挑出墙外的最大尺寸为1800毫米。踏步板由混凝土构件厂预制,混凝土设计标号为400号。采用φ5冷拔预应力 A hotel in Zhenjiang City was constructed in 1974. It was a six-story hybrid structure. The main staircase was prefabricated with pre-stressed cantilevered treads. The dimensions of the tread plate are shown in Figure 1. The step board is pressed into the wall size, the bottom layer is 370 mm, the second to sixth layers are 240 mm, and the largest size outside the wall is 1800 mm. The tread board is prefabricated by a concrete member factory, and the concrete design number is No. 400. Use φ5 cold drawn prestress