鋼骨鋼筋混凝土構件扭矩強度與行為研究

Abstract

本研究以實驗方式探討鋼骨鋼筋混凝土(Steel Reinforced Concrete, SRC)梁構件承受純扭矩作用之強度與行為與SRC梁構件扭矩強度之計算模式。設計16組SRC梁試體，試體之設計參數有鋼骨、橫向扭力筋與縱向主筋。試驗結果顯示SRC試體包覆H型鋼骨，因鋼骨之扭矩強度甚小，故SRC試體較RC試體於極限扭矩強度僅有些微的提昇；然而SRC試體之扭矩-扭轉角行為異於RC試體，SRC試體於達到極限扭矩強度後，強度呈現較緩慢之下降，能有較佳的韌性行為。SRC試體內之橫向扭力筋量之增大將提昇試體之扭矩強度，配置#3@10 cm橫向扭力筋系列試體之實驗值幾乎皆高於規範計算值，然而配置雙排#3@10 cm之橫向扭力筋試體之實驗值遠小於規範之計算值。包覆不同鋼骨深度的SRC試體之極限扭矩強度無一致性的試驗結果。增加縱向扭力筋能提昇SRC試體的極限扭矩強度，惟於橫向扭力筋量越高之情況下，縱向扭力筋於SRC試體的扭矩強度之影響越小。SRC梁試體於達到其極限扭矩強度時，H型鋼骨尚未降伏，其於扭矩強度之貢獻相對於RC梁甚小，於實務設計上可保守的忽略H型鋼的扭矩強度。

This study experimentally investigates the strength, behavior and calculation of torsional strength of steel reinforced concrete (SRC) members subjected to pure torsion. Sixteen beam specimens were designed to include design parameters of structural steel, closed stirrup, and longitudinal reinforcement. Test results indicate that the SRC beams, enclosed the H-shaped structural steel, reached slightly higher torsional strength than reinforced concrete beams did due to the low torsional resistance of the H-shaped structural steel. However, the torque-twist curves for SRC specimens were different from those for RC specimens. The torsional strength of the SRC specimens gradually decreased and possessed better toughness after reached the peak strength as indicated in the torque-twist curves. Increasing the amount of closed stirrups can enhance the torsional strength of the SRC specimens. Specimens with No. 3@10 cm closed stirrups can develop higher torsional strength than calculated strength followed the code, while specimens with 2-No. 3@10 cm closed stirrups can not even attain the strength calculated by the code. Specimens enclosed different size of the structural steel did not achieve consistent test results. In addition, increasing the amount of longitudinal reinforcement can increase the torsional strength. Nevertheless, the effect becomes little for specimens with higher amount of closed stirrups. The structural steel did not yield while the SRC specimens reached the ultimate torsional strength. Because the negligible contribution to the torsional strength compared with RC beam, the H-shaped structural steel can be conservatively neglected to calculate the torsional strength of SRC beam in practical design.