不同三维尺寸双层柱面网壳的行波效应影响

Traveling wave effect of double-layer cylindrical latticed shells with different three-dimensional sizes

为了探究高通滤波的最佳截止频率及大跨空间结构三维尺寸与行波效应的关系,采用时程分析法对不同三维尺寸双层柱面网壳进行多点输入与一致输入的对比分析,研究结构间的地震响应规律。结果表明:截止频率不小于0.1Hz的高通滤波可有效消除原始地震记录的零线漂移现象,而引起结构最大地震响应的最佳截止频率各不相同;行波效应对横杆及腹杆无明显不利影响,对纵杆不利影响较大,下弦纵杆内力普遍极小而上弦纵杆内力较大;结构高度或跨度增大会减小行波效应的影响程度,但行波效应与结构高跨比无直接关系,且行波效应影响范围与结构高度有关而与跨度基本无关;结构长度增加会增大行波效应的影响程度及影响范围。可见,高通滤波的最佳截止频率在不同应用中需具体分析但不宜小于0.1Hz,分析此类结构行波效应仅需针对上弦纵杆,而行波效应对结构的影响与三维尺寸及支承方式均有关。

In order to research the best cut-off frequency of high-pass filtering and the relation between three-dimensional sizes of large-span spatial structure and traveling wave effect,the time-history method was used to investigate seismic response of double-layer cylindrical latticed shells with different three-dimensional sizes under multiple-support excitation and single excitation.The results show that the deviation of zero-line of original seismic records can be removed effectively by high-pass filtering with cut-off frequency of no less than 0.1 Hz,and the best cut-off frequency of various seismic records which result in the maximum seismic response of the structure are different.The traveling wave effect has no obviously disadvantaged effect on transverse and web members,and has greatly disadvantaged effect on longitudinal members,which internal force is usually small at the bottom chord and large at the top chord.The increase of height or span of structure decreases the degree of the traveling wave effect,which is irrelevant with height-span ratio,and the range of the traveling wave effect is not related to the span but height.The increase of length of structure increases the degree and range the traveling wave effect affects.It is concluded that the best cut-off frequency of high-pass filtering should be analyzed specially in different practices but not be less than 0.1 Hz,and only the longitudinal members at the top chord are needed for the research of the traveling wave effect,and the influence traveling wave effect results in is both related to the three-dimensional sizes and supporting form.