高強度鋼管混凝土柱梁柱行為探討

Abstract

由於鋼管混凝土具有高勁度、強度及韌性之特性，且又於澆置混凝土時，不須額外模版；因此，其在現代建築構造中，已逐漸佔有一席之地。 本研究首先以實驗方式探討填充高強度混凝土之加勁與未加勁CFT柱在同時承受軸力與彎矩作用下之行為。本研究共製作28支試體，考慮參數有鋼管之截面形狀（圓形和方形）、B/t（40及70），及加勁方式，和軸力比（P/Pn=0，0.1，0.2，0.3，0.5）。另外，再以斷面法配合傳統鋼筋混凝土中常用混凝土應力與應變模式估算鋼管混凝土梁柱行為。 結果顯示在不同軸力下受彎矩之行為方面，八角形加勁方式對極限彎矩強度及韌性上均有良好增益。試驗結果與各規範比較顯示，B/t (D/t)=70之試體並無法達到規範要求之彎矩強度；B/t (or D/t)=40之試體則超過規範許多；所施加之軸力比愈大，其韌性則愈差。而斷面分析法亦可以初步模擬實驗試體之行為趨勢。

This study investigates the beam-column behavior of high-strength concrete-filled tube. Twenty-eight specimens were tested to study the effects of the width-to-thickness ratio (B/t= 40 and 70), the axial load level (P/Pn = 0.0, 0.2, 0.3, 0.4, 0.5), cross section shape (round or rectangular), and proposed stiffening scheme on the stiffness, ultimate strength, and ductility of CFT columns. Moreover, sectional analysis method with different confined concrete models was also used to compute moment to curvature curves with the comparison to the experimental results. The experimental results indicate that the proposed stiffening scheme can significantly enhance the ultimate strength and ductility of square CFT columns. Current specifications (AIJ, EuroCode4) overestimate the ultimate strength, Mu, of the specimens with B/t = 70 but underestimate that for B/t = 40. The ductility of the specimens significantly decreases with the increase of the applied axial load level. The results obtained from sectional analysis method could well match with the experimental results by choosing appropriate parameters in Saenz’s concrete model.