腹板開孔之冷軋不鏽鋼槽型斷面腹板皺曲強度

Abstract

本研究以實驗方式探討在端點雙翼板(End Two-Flange, ETF)受集中載重下之具腹板開孔冷軋不鏽鋼槽型斷面之腹板皺曲強度及行為，材料選用SUS 304型沃斯田不鏽鋼，開孔為圓形孔位於腹板正中央，上下支承墊與試體翼板間無固定，以48支不同腹板細長比、不同開孔直徑、不同開孔位置的試體實驗。本研究並以有限元素分析試體，與實驗結果互相驗證。實驗結果顯示在不同試體條件下腹板開孔強度折減係數皆不相同。本研究根據實驗結果提出了在載重條件為ETF下折減係數建議值公式。根據提出之折減係數，影響具腹板開孔之冷軋不鏽鋼腹板皺曲強度的主要因素為開孔大小，其次為開孔距離。建議值與實驗結果比較顯示，開孔直徑越大與開孔位置距離支承墊越接近，折減係數越難預測。有限元素分析結果顯示可以有效地模擬試體破壞行為和腹板皺曲強度。

This study experimentally investigates the web crippling strength of cold-formed stainless steel channel sections with hole on the web under the end two-flange (ETF) loading condition. The channels were austenitic type 304 stainless steel. The holes were located at mid-depth of the webs. Flanges of the channel sections were not fastened to the supports. This experiment included 48 test specimens with different web slenderness ratio, hole diameter, and hole location. Finite element analyses were further conducted and the results were compared with test data. Test results demonstrated that the web crippling strength reduction factors were different for various specimens. According to the test results, strength reduction factors were proposed for the ETF loading conditions. Based on the strength reduction factors, the major factors influencing the web crippling strength of the cold-formed stainless steel with web hole was the hole size and, the next, the distance between the hole and the edge of the bearing. Both the proposed strength reduction factors and the test results showed that the larger the hole diameter and closer the hole to the bearing resulted in the more difficult to predict the strength reduction factor. The finite element analysis can effectively predict the specimen behavior and web crippling strength.