铁路桥墩台顶帽之主要作用,是将支座反力均匀地传递于桥墩台。因此顶帽系一受力构件,其强度及构造均有一定要求。同时,顶帽之平面构造还要满足安装支座、架梁、养护的需要。在先后四本铁路桥涵设计规范中,均对顶帽构造作了规定,现将其演变情况概述如下。一在1951年发布和施行的《铁路桥涵设计规程》中,作了如下规定: “第291条梁桥桥墩及桥台顶部其支座以下部分应修建钢筋混凝土之顶帽,其厚度 The main function of railway bridge pier top hat is to transmit the bearing reaction force evenly to the bridge pier. Therefore, the top cap is a force component, its strength and structure have certain requirements. At the same time, the top hat of the plane structure but also to meet the installation of bearings, beams, conservation needs. In the four railway bridges and culverts design standards, the structure of the top hat has been stipulated, and the evolution of the bridge is summarized as follows. A “Railway Bridge Culvert Design Code,” promulgated and implemented in 1951, made the following provisions: "Article 291 beam bridge piers and abutments at the top of its support should be built under the top of reinforced concrete top hat, the thickness of its