考量二次變位理論之拋物線型鋼鍵混凝土梁預力預測

Prestress Force Prediction for Concrete Beams with Parabolic Tendon considering Second-Order Deflections

薩安莫(AHMED ABDELFATAH SADDEK)

指導教授 ： 林子剛

國立交通大學/工學院/土木工程系所/碩士(2019年)

摘要

後拉混凝土梁中，若能準確地預測其預應力，可增加其安全性。目前，由於現有理論之間的矛盾，導致理論分析之預力混凝土梁變位與實驗結果不一致。因此，本研究利用「壓縮－軟化」理論，可將宋等人(2000)所推導之公式應用於拋物線型鋼腱混凝土梁，試著使分析之位移更趨於實驗所得，提高其精確度。此外，本研究也對具有拋物線粘合肌腱的高強度混凝土PC梁進行了一系列長達2.5個月的實驗，尤其針對漸進式短期預應力損失的PC簡支梁進行靜力試驗。相反地，若考量到割線彈性模數，壓縮－軟化理論的放大係數公式能很好地描述靜態撓取變形量和預應力之間的關係。最後，透過本文的修正，即可更輕易地預測出拋物線型鋼腱混凝土之撓曲變位，進而求得其預應力，改善安全性。

關鍵字

混凝土梁 ； 「壓縮－軟化」理論 ； 拋物線型鋼腱 ； 抗彎剛度

並列摘要

The deflected shape of a post–tensioned concrete beam with a parabolic tendon, subjected to an additional vertical load, was short-term measured in several laboratory experiments. The “compression–softening” theory was applied in this study. Currently, due to the conflicts among existing theories, the analytical solution for properly considering the structural behavior of these prestressed members is not clear. Thus, more ways had been tried to make the analytical displacements more similar to the experimental displacements. A series of experiments were conducted on a PC beam specimen of high strength concrete with a parabolic bonded tendon for a period of approximately 2.5 months. Specifically, the simply supported PC beam was subjected to the static tests under progressive short–term prestress losses. Conversely, the relationship between static deflection shape and prestress force is well described by the magnification factor formula of compression–softening theory taking into account the secant elastic modulus. Furthermore, according to the “compression-softening” theory, the Song’s formula (2000) was applied on the concrete beam with a parabolic tendon. Finally, after all these modifications, it has been possible to predict the flexural displacements for the concrete beam with a parabolic tendon.

並列關鍵字

Concrete beam ； “compression–softening” theory ； parabolic tendon ； flexural rigidity

參考文獻

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