摘要
本文研究了橡胶支座基础隔震结构的高宽比限值。研究基于保证隔震结构在强震中不倾覆的两个充分条件,一个是橡胶隔震支座不能产生拉应力,另一个是隔震支座压应力不超过容许值。本文推导了隔震结构高宽比限值的显式并给出了针对不同建筑类别、不同设防烈度、不同场地条件和不同隔震层阻尼比的高宽比限值。在支座的轴力计算中,还考虑了竖向地震作用和荷载的最不利组合。研究发现,当控制条件为支座不产生拉应力时,高宽比限值随隔震结构周期的增加而增加;当控制条件为支座压应力不超过容许值时,高宽比限值随隔震结构周期的增加而减小。因此,存在一个临界周期使高宽比限值取得极大值。研究还发现,存在一个最大的隔震结构周期使高宽比限值等于零或隔震层位移超过容许值。将隔震结构的周期与临界周期和最大隔震周期比较,就可以得到相应高宽比限值的表达式。最后,按照简单、安全的原则,将各种工况下的高宽比限值进行了归并,给出了高宽比限值的设计建议值。同时,还按设计规范提供的结构周期计算公式计算了隔震结构的高度限值。
The limit of height-width ratio of base-isolated structure with rubber bearings is investigated. Two sufficient conditions that could keep the base-isolated structure from overturning during strong earthquake are considered. One is that rubber beatings should not be subjected to tensile stress, and the other is that the compressive stress in rubber bearings should not exceed the allowable value. The derivation of limit ratio formulas are performed and the results are presented corresponding to different building categories, earthquake fortification intensities, site classifications, and damping ratios of isolated story. In the formulas for the axial force in rubber bearings, vertical seismic action and the most unfavorable load combinations are considered. It is found that, the limit ratio increases with the isolation period when it is confined by the first sufficient condition, and decreases when confined by the second one. So there exists a critical period, at which, the limit ratio reaches its maximum value. It is also found that there exists a maximum isolation period, at which, the limit ratio is zero or the horizontal displacement of the rubber bearing exceeds the allowable value. By comparing the isolation period with the critical and maximum periods, the limit ratio can be obtained by using the corresponding formulas. In conformity to the principle of simplicity and safety, the calculated limit ratios were summarized to obtain the suggested values. The limit height of base-isolated structures are also calculated by using the period formulas of non-isolated structures as suggested in the design code.
出处
《土木工程学报》
EI
CSCD
北大核心
2007年第4期13-20,共8页
China Civil Engineering Journal
基金
国家自然科学基金(50378020)
福建省科技重点项目(2006Y0018)
关键词
隔震结构
高宽比
竖向地震作用
最不利组合
周期
base-isolated structure
height-width ratio
vertical seismic action
the worst combination
period
