现浇盒状内模空心楼盖的直接设计法

Direct Design Method for Cast-in-Situ Box-Filler Hollow Floor

为研究直接设计法对盒状内模空心楼盖的适用性,以典型的四角柱支撑盒状内模空心楼盖为分析对象,在校核分析模型后,用ABAQUS软件完成了224个算例分析。考察了具有相同参数的空心楼盖和对照实心楼盖的截面弯矩分布的异同,进而分析了空心率、板格边比、柱跨比、梁板相对抗弯刚度比和边梁抗扭刚度比等5个因数对空心楼盖弯矩分布的影响,得到了内板格和端板格各弯矩控制截面的一次弯矩分配系数以及各控制截面内柱上板带板、跨中板带和柱上板带梁的二次弯矩分配系数,并与规范建议的直接设计法系数做了对比。分析结果表明:空心楼盖与实心楼盖在边计算单元和中计算单元间以及各计算单元内的弯矩分布规律类似,差异主要体现在跨中正弯矩的分配上;当板格边比不大于1以及柱跨比不大于0.2时,柱(或柱帽)的尺寸效应对截面弯矩一次分配的影响可以忽略;规范中直接设计法的分配系数与计算值在部分截面有较大差距,需对柱上板带负弯矩、柱上板带正弯矩、柱上板带梁的弯矩分配做相应调整。根据分析结果,文章最终提出了直接设计法一次弯矩分配系数表和二次弯矩分配系数表供研究和设计应用。

To analyze the applicability of the direct design method to the box-filler hollow floor , 224 specimens of cast-in-situ box-filler hollow floor and solid floor supported by columns were computed by ABAQUS .Both a hollow core floor and the corresponding solid floor were analyzed and the section moments were achieved .Then parametric analysis of the hollow floor was carried out .The column size ratio ,hollow ratio ,span ratio ,beam relative flexural stiffness and beam relative torsional stiffness were all considered as analysis parameters . T he first-round and second-round moment distribution coefficients in both interior and edge panel were obtained .The results show that ：for the hollow floor and solid floor ,the moment distribution in interior computational strip and edge computational strip are similar ,the difference of moment distribution mainly lies in the positive moment .When the span ratio ≤1 .0 and the column size ratio≤0 .2 ,the impact caused by support size can be ignored ;There is still a relatively large gap between calculated value in moment distribution coefficient and codes in some part of the critical sections ,some coefficient must be adjusted . From the analysis results , the first-round and second-round moment＆nbsp;distribution coefficient tables were presented for research and engineering design .