拉-压杆模型合理性量化评价指标研究

QUANTIFICATION INDEX RESEARCH FOR THE RATIONALITY OF STRUT-AND-TIE MODEL

目前在国内进行混凝土应力非规则区域设计时,一般按照经验或构造要求进行配筋设计,这不可避免地会影响该区域的设计质量,而国外规范在进行混凝土应力非规则区域设计时多采用以拉-压杆理论为基础的设计方法。虽然拉-压杆理论已经被多国规范所采纳,但对拉-压杆模型合理性问题尚没有量化的评价指标。为此,以最小余能原理为基础,提出以余能偏差系数作为拉-压杆模型合理性量化指标,并以牛腿和深梁为例,按不同的拉-压杆模型设计配筋,进行极限承载力分析,对所提量化指标的可行性进行验证。结果表明:余能偏差系数对拉-压杆模型合理性比较敏感,可以作为拉-压杆模型合理性的量化评价指标,在此基础上推导了拉-压杆模型的叠加算法,得到了一些有意义的结论。

The design for the stress discontinuous region in concrete members mainly bases on the experience or requirement of construction in China. It inevitably affects the design quality of concrete. Nowadays, the design method for the concrete stress discontinuous region is based on strut-and-tie model theory in overseas. Concrete design codes for strut-and-tie theory have been adopted by many countries. But there are no quantification indices for the rationality of strut-and-tie models. Bases on the principle of minimum complementary potential energy, propose to take the factor of a complementary potential energy deviation as the quantification index of the rationality of strut-and-tie models. In order to verify the feasibility of the quantification index, take a corbel and a deep beam as examples, the reinforcements design according to different strut-and-tie models. And the feasibility is verified by the examples. The analysis result shows that the factor of the complementary potential energy deviation is very sensitivity to the rationality of strut-and-tie models. It can be taken as a quantification index of the rationality of strut-and-tie models. The superposition algorithm of strut-and-tie models is derived. Some signification conclusions are obtained.