高強度混凝土充填箱型鋼柱於高軸力下之耐震試驗

Seismic Tests of High Strength Concrete Filled Box Columns under Large Axial Loads

周中哲(Chung-Che Chou) ； 吳松城(Sung-Cheng Wu)

《結構工程》 32卷1期 (2017/03) Pp. 25-48

https://doi.org/10.6849/SE.201703_32(1).0002

摘要

高樓建築結構中的低樓層柱常會因載重要求及尺寸的限制而有使用高強度材料的需求， 因此本研究探討高強度混凝土充填高強度箱型鋼柱（Concrete Filled Box Column, CFBC）於高及低軸力(40%及20%軸力強度)下之耐震行為，主要試驗參數包括鋼柱寬厚比、軸力大小及斷面配置，共計有六組試體，試驗方式為對柱施加固定軸力並進行反覆側推試驗。鋼柱方形斷面寬分別為420、400 及280 mm，寬厚比分別為11、18 及30，試體使用高強度SM 570M 鋼材（實際降伏強度520~580MPa）及高強度混凝土（實際f_c^'= 80 MPa）。研究結果顯示寬厚比增加會小幅降低柱韌性，但柱軸力大小對柱韌性之影響非常顯著，於高軸力下柱的韌性低，而銲接箱型柱斷面內充填混凝土與否對韌性並無明顯影響。本研究也將實驗所得的強度與各國規範進行比較，發現歐洲EC 規範及日本AIJ 規範對於高強度混凝土充填箱型鋼柱之強度預測較為準確，美國AISC、ACI 及台灣規範均過於保守；各規範對於高強度箱型鋼柱之強度預測均偏於保守，對於寬厚比較小之柱試體，預測誤差較大。

關鍵字

高強度材料 ； 混凝土充填箱型鋼柱 ； 高軸力梁柱構件 ； 耐震試驗

並列摘要

The cyclic behavior of high strength Concrete Filled Box Column (CFBC) under large axial loads was experimentally investigated. The parameters in the study included the width-to-thickness (b/t) ratio, axial load level and section type. Total six beam-column specimens were tested under a constant axial load and an increasing cyclic loading. The CFBC specimens were 280 to 420 mm in width and 2000 mm in height. Nominal b/t ratios varied from 11 to 30. All specimens were made of high strength steel SM 570M with a nominal yield strength of520~580 MPa.Three specimens were filled with high strength (80 MPa) concrete. Experimental results indicated that ductility decreases significantly with an increase in either axial load level or b/t ratio of the steel. The ductility does not change significantly whether concrete is infilled in the steel box column. Eurocode (EC 2004) and Architectural Institute of Japan (AIJ 2010) have good prediction in the flexural strength of high strength CFBC. AISC-LRFD (2010), ACI 318 (2011) and Taiwan Steel Design Code (2010) are too conservative in predicting the flexural strength of high strength CFBC. All the design codes are conservative in predicting high strength steel column moment capacity, especially for small b/t ratios.

並列關鍵字

High strength material ； Concrete filled box column ； High axial load beam-column specimen