鋼筋混凝土梁之扭力破壞機率

The Probability of Torsion Failure of Reinforced Concrete Beams

呂文堯(Wen-Yao Lu) ； 林英俊(Ing-Jaung Lin)

《建築學報》 44期 (2003/10) Pp. 35-47

https://doi.org/10.6377/JA.200310.0004

摘要

本文旨在探討根據ACI規範設計的筋混凝土梁之扭力破壞機率。本文將Hsu的軟化桁架模型加以修正，以作為鋼筋混凝土梁扭力強度之理論模型，並在考慮混凝土強度、鋼筋強度，斷面尺寸，扭力強度之模型誤差及載重等皆為隨機變數之情形下以蒙地卡羅法分析鋼筋混凝土梁之扭力破壞機率。研究結果顯示，採用Grade 40鋼筋為扭力鋼筋之梁，其扭力破壞機率皆在可接受之範圍，但對於採用 Grade 60鋼筋為扭力鋼筋且混凝土強度較低的梁其破壞機率偏高，較有安全之顧慮。研究結果亦顯示，扭力破壞機率會隨著混凝土強度的提高而降低，也會隨著扭力箍筋間距的增加而降低。混凝土強度對於梁之扭力破壞機率並使高強度混凝土梁之扭力設計不致有過於保守的現象。

關鍵字

扭力破壞機率 ； 蒙地卡羅法 ； 扭力強度 ； 鋼筋混凝土

並列摘要

In this study, the Monte Carlo technique is used to investigate the probability of torsion failure of reinforced concrete beams designed based on ACI Code. The strength of concrete and steels, the cross-section dimensions, the model error of torsional strength and the loads are all considered as random variables. In this study, the theoretical torsional strength is based on the modified softened truss model theory. The results show that the probability of torsion failure for beams with Grade 40 reinforcement is acceptable. For beams with Grade 60 reinforcement and low-strength concrete, the failure probability is relatively high. The results also show that the probability of torsion failure decreases with the increase of concrete strength and spacing of trosional reinforcement.

並列關鍵字

probability of torsion failure ； Monte Carlo technique ； torsional strength ； reinforced concrete beams

參考文獻

American Concrete Institute Committee 318(2002).Building Code Requirements for Structural Concrete (ACI 318-02) and Commentary (ACI 318R-02).Detroit:American Concrete Institute.

American Institute of Steel Construction(1993).Commentary on the Load and Resistance Factor Design Specification for Structural Steel Buildings.Chicago:American Institute of Steel Construction.

ASCE-ACI Committee 445 on Shear and Torsion(1998).Recent Approaches to Shear Design of Structural Concrete.Journal of Structural Engineering.124(12)

Bartlett, F. M., MacGregor, J. G.(1996).Statistical Analysis of the Compressive Strength of Concrete in Structures.ACI Material Journal.93(2)

Bradburn, J. H.(1968).An Investigation of Combined Bending and Torsion in Rectangular Reinforced Concrete Members.Raleigh:Department of Civil Engineering, North Carolina State University.