下肋U型钢-混凝土组合空腹夹层板的动力特性分析

Dynamic Characteristics Analysis of Open-web Sandwich Plate of U-shaped Steel-concrete Composite on Bottom Ribs

为了解下肋为混凝土外包U型钢的组合空腹夹层板的动力特性,将下肋U型钢按轴向刚度等效为混凝土,采用8节点弹性块体单元应用子空间迭代法求解自振方程计算了50个算例。结果表明：组合空腹夹层板的频率具有密集分布特点,振型与相同支承条件的实心平板类似;支承梁刚度增大有利于提高结构基频,但梁截面高度不宜大于跨度的1/14;基频随楼盖高跨比的提高而增大,结构高跨比可采用1/25-1/20;过大的肋刚度将使结构基频降低,因此肋截面高度可按网格尺寸的1/14-1/8采用;增大下肋U型钢的厚度对提高结构基频是有利的;过小的网格划分频数将降低结构整体刚度,网格长度不宜超过2.5 m;支承条件明显影响楼盖的动力特性,振动舒适度分析时应计及支座刚度影响,提高支座刚度是增大楼盖基频的有效措施。

In order to study dynamic characteristics of open-web sandwich plate of U-shaped steel-concrete composite on bottom ribs,the 50 structures whose U-shaped steel of bottom ribs are replaced to concrete by equal axial stiffness were calculated according to 8 node elastic block element and subspace iteration method. The results show that mode of composite open-web sandwich plate are similar with plate under same supporting conditions,and its frequency is of dense distribution.Its supporting beam section height should not be greater than its span of1 / 14,while improving stiffness of supporting beams is beneficial to increasing structure frequency.The fundamental frequency increases along with the improving of structure height-span ratio which could use 1 / 25 ~ 1 / 20. The ribs section height should use the 1 / 14 ~ 1 / 8 of the grid size,because larger rib stiffness will reduce the structural fundamental frequency.Increasing bottom ribs U-shaped steel thickness is advantageous to improving fundamental frequency.Grid length which is too long to reduce the structural stiffness should not be more than 2. 5 m. The measure used for improving bearing stiffness is very effective to increase floor fundamental frequency,and vibration comfort analysis must consider its influence,while the dynamic characteristics of the floor is obviously affected by supporting conditions.