沉箱頂版受垂直力及彎矩之應力分佈

Abstract

在本文中，將以3D模型來模擬沉箱頂版在不同厚度、不同載重狀況以及上方柱子之不同長度半徑影響下，最大應力斷面內部之應力分佈情形，並且與工程界的設計方式進行比較。 由分析結果可以知道，沉箱頂版上方柱子長度增加時，頂部壓力區之正應力集中現象會變小，而底部拉力區正應力集中則會增大，進而變成由拉力區及壓力區平均分攤的分部情況，而剪應力也會由頂部的應力集中漸漸趨於沿斷面呈現較為均佈的狀態。頂版厚度的增加則會使斷面最大剪應力發生處由斷面中心往下偏移。柱子半徑小的話，斷面的應力集中現象會很高。由於混凝土抗拉強度不高，所以很有可能會在由於底部應力集中的現象而受拉開裂。

In this study, 3D model is used to discuss the stress distribution at the cross-section of the maximum stress under variety of thickness of plate, loading condition and radius of column above plate. The results were compared with the design method used in industry. By the result, we could know that if the length of the column above the cover plate increased, the phenomenon of normal stress concentration will decrease at the top and increase at the bottom. The shear stress will distribute more uniformly along the cross-section, and the position on which the maximum shear stress occurs will shift down form the center of cross-section as the thick of the cover plate increased. The lower tensile strength of concrete, probably produce cracks at the bottom of the cover plate due to the stress concentration.