火害對自充填混凝土握裹力影響之研究

Abstract

本研究在於探討自充填混凝土(SCC)火害後握裹強度折減的狀況並且與普通混凝土(OPC)作一比較，並同時觀察抗壓與劈裂強度折減的情形；此外，在常溫的部分並埋置鋼筋應變計以觀察兩種混凝土在拉拔過程當中握裹應力分佈的情況。 本研究升溫方式採用CNS 12514的建議值而在火害溫度的部分採用四種高溫300、500、600、750℃，且在爐溫達目標溫度時即恆溫直至試體中心亦達此溫度為止。 就本研究結果來看，(1)常溫下SCC握裹應力分佈的情況較OPC要來的平均，由此現象可看出SCC較均質。(2)常溫下SCC確實能夠提供較OPC要來的好的握裹力。(3) 火害後SCC的抗壓強度折減的情況與OPC差不多。(4) 火害後SCC的握裹強度與劈裂強度折減的情況則較OPC要來的稍差一點(約低5~7%)。(5)混凝土強度對於火害後強度的折減影響不大，折減的多寡反倒是決定於火害溫度。(6)在相同埋設深度（29cm）時，D19的鋼筋折減程度與D25的鋼筋大致相同。

The objective of this research is to study the residual bond strength of self-compacting concrete (SCC) and compare with that of ordinary property concrete (OPC) after fire. At the same time, we also observe the residual compressive strength and the residual split-cylinder strength of SCC and OPC. At room temperature, we use strain gages for observing the bond stresses distribution of SCC and OPC. The temperature rise follows CNS 12514 and the target temperatures are 300℃, 500℃, 600℃,750℃. From this studying, it is found that (1) at room temperature, bond stresses distribution of SCC is more uniform than OPC, (2) at room temperature, the bond strength of SCC is better than that of OPC, (3) the residual compressive strength of SCC and OPC after fire is about the same, (4) the decrease of residual bond strength and residual split-cylinder strength of SCC after fire are more than OPC, (5) the decrease of strength after fire damage depends on the fire temperature rather than concrete strength, (6) the residual bond strength for bars of D19 and D25 after fire is about the same.