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Displacement response analysis of base-isolated buildings subjected to near-fault ground motions with velocity pulse

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Abstract

In order to study the influence of the velocity pulse to seismic displacement response of base-isolated buildings and the differences of the influent of the two types of near-fault ground motions with velocity pulse to seismic response of base-isolated buildings, the seismic responses were analyzed by three dimensional finite element models for three base-isolated buildings, 4 stories, 9 stories and 14 stories. In this study, comparative analyses were done for the seismic displacement responses of the base-isolated structures under 6 near-fault ground motion records with velocity pulse and no velocity pulse, in which, 6 artificial ground motion time histories with same elastic response spectrum as the 6 near-fault ground motion records were used as the ground motion with no velocity pulse. This study indicates that under the ground motions with velocity pulse the seismic displacement response of base-isolated buildings is significantly increased than the ground motions with no velocity pulse. To the median-low base-isolated buildings, the impact of forward directivity pulses is bigger than fling-step pulses. To the high base-isolated buildings, the impact of fling-step pulses is bigger than forward directivity pulses. The fling-step pulses lead to large displacement response in the lower stories.
文章编号1005-0930201401-0001-013 中图分类号TU352. 1 文献标识码A
doi10. 3969 / j. issn. 1005 -0930. 2014. 01 001
收稿日期2013-03-20修订日期2013-08-30
基金项目国家重点基础研究发展计划2011CB013601 国家科技重大专项2011 ZX06002-010-15 中央级公益性
科研院所基本科研业务专项DQJBDB28
作者简介贺秋梅1978
助理研究员 E-mailheqiumei06@ 126 com
近断层速度脉冲型地震动作用基础
隔震建筑位移反应分析
贺秋梅
1
李小军
12
3
1. 中国地震局地球物理研究所
北京 1000812 北京工业大学建筑工程学院
北京 1000223. 环境保护部核
与辐射安全中心
北京 100082
摘要49层和 14 3个基础隔震结构为计算模型
选取了3条向前方向
性效应速度脉冲及3条滑冲效应速度脉冲地震动记录
并以这些速度脉冲型地
震动的弹性反应谱作为目标谱分别合成 6条无速度脉冲的地震动时程样本
比分析了在有
无速度脉冲的地震动激励下基础隔震结构的位移反应探讨了地
震动的速度脉冲对基础隔震结构位移反应的影响
并详细分析了两类不同产生
机制的速度脉冲对基础隔震建筑结构地震位移反应的影响差异研究结果表明
速度脉冲使基础隔震结构位移反应明显增大
对于中低层基础隔震建筑的位移
反应滑冲效应速度脉冲的影响更大一些
而向前方向性速度脉冲对高层建筑位
移反应影响更大
滑冲效应速度脉冲使得结构底部变形更大
导致结构可能发生
底层倒塌破坏
关键词近断层速度脉冲地震动记录基础隔震建筑位移反应
近几十年来的多次大地震
Kobe 地震1995Mw7. 2Kocaeli 地震1999Mw7. 4
集地震1999Mw7 6 和汶川地震2008Mw7 9
在断层附近都产生了严重的
震害这些地震之所以对周围工程结构产生如此严重的破坏
与近断层区域的地震动
强烈有关
更与近断层地震动所具有的长周期
大位移和速度脉冲等特性有关
这些特性对工程结构反应影响的探讨成为目前相关研究的热点问题已有究表
断层的破裂向前方向性效应和滑冲效应都可致使近断层地震动具有明显的速度脉冲
从而在振幅
频谱和持时3方面与远场地震动有明显的差别
速度脉冲加重了对工程结
构的破坏1-5然而
目前很多学者研究速度脉冲地震动作用下工程结构的动力响应
并没有区分两种不同产生机制的速度脉冲运动对结构动力响应产生何种不同的不
利影响4-5直到最近Kalkan 等分析了这两种不同速度脉冲对 3度分 46
层和 13 层的钢框架建筑结构地震响应的影响6杨迪雄等利用广义层间位移谱方法
22 1
2014 2应用基础与工程科学学报
JOURNAL OF BASIC SCIENCE AND ENGINEERING
Vol. 22No. 1
February 2014
将高层建筑等效化为一个弯剪型悬臂梁
从地面输入理想的简单脉冲
前方向性效应脉冲
滑冲效应脉冲和无脉冲3组近断层地震动记录
对弯剪组合梁进行
了层间变形分析7以上研究结果表明
滑冲效应脉冲主要激起抗弯框架体系的基本
振型响应
导致结构的最大层间变形发生在较低楼层破裂向前方向性效应脉冲能够
激起框架结构高阶振型的响应
中国许多重要的城市如北京
成都
西
乌鲁木齐和昆明等有大型活动断层穿越
或位于附近8
在这些近地区
采用基础隔震等减震措施已经修建了一些体育场
馆以及多层
中高层民基础隔震结构通过在建筑物或构筑物基底设置控制机
构来隔离地震能量向上部结构传输
使结动减
避免地震破坏基础隔震结构在
中远震场地减震效果良好
但近断层地震动明显的长周期速度和位移脉冲运动可能对
隔震建筑的抗震性能和设计带来不利影响
这种不利影响究竟有多严重
还需要深入
探讨 Jangid EDFElectricite-de-France隔震系统可能是近断层基底隔
震设计的最佳选择9杨迪雄等的研究表明
经参数优化设计的考虑近断层速度脉冲
型地震动作用的隔震结构
能同时满足近断层速度脉冲型和非速度脉冲型地震动作用
下的结构设计需求10然而
相比传统的抗震结构而言
两种产生机制不同的速度脉冲
型地震动对基础隔震建筑结构位移反应的影响差异研究还较少开展
且两种速度脉冲
对基础隔震建筑结构位移反应的影响差异究竟多大
还需要进行更详细的量化分析
另外
在分析速度脉冲对结构动力反应的影响时
很多学者一般采用有
无速度脉冲的
两组实际地震动记录作为输入
但无论怎样挑选地震记录
这些记录的反应谱特性之
间仍将存在很大的差异
地震动反应谱之间的差异对结构反应必定会带来影响
结果的差异将不能真实反映地震动的速度脉冲等特殊特性的影响
从而会影响到研究
结果的可信程度311
本文结合 3栋基础隔震建筑
选取多条不同产生机制的速度脉冲型地震动记录
以这
些实际的含有速度脉冲的地震动记录作为地震动输入
同时以人工模拟的具有相同加速
度反应谱而具有不同峰值速度的无速度脉冲地震动时程作为地震动输入进行比较
3
栋基础隔震建筑进行不同地震动输入下的地震位移反应计算
探讨地震动的速度脉冲对
基础隔震建筑位移反应的影响
以及两类不同产生机制的速度脉冲对基础隔震建筑地震
位移反应的影响差异
1计算模型概况
1. 1 上部结构模型
采用框架结构
采用 C30 混凝土
计算模型参数见表 1
房屋柱
梁布置见图1.
层平面如图 1所示基于以下两个应用广泛的假定进行隔震建筑结构的动力分析上部
结构处于弹性范围楼板平面内无限刚
平面外刚度为零将钢筋混凝土梁
柱等效为均质
的杆单元
将楼板等效为均质的壳单元
其材料特性以混凝土特性为主考虑了梁单元的
弯曲变形
剪切变形
柱单元的弯曲变形
剪切变形和轴向变形假设楼板在自身平面内为
绝对刚性
在平面外的刚度忽略不计
2应用基础与工程科学学报 Vol. 22
1计算模型参数
Table 1 Parameters of calculation model
模型 梁宽 ×/mm 柱截面/ mm 楼板厚/ mm / m 总层数
模型一 350 × 500 550 × 550 100 3. 6 4
模型二 400 × 600 650 × 650 100 3. 6 9
模型三 400 × 700 700 × 700 150 3. 6 14
1某办公楼标准层平面图单位mm
Fig. 1 An office building standard floor planunitmm
1. 2 铅芯橡胶隔震支座模型
计算模型采用的铅芯橡胶隔震支座
在非线性分析中采用双轴非线性滞回单元来模
它对于两个剪切变形的自由度有耦合的塑性属性
而对于其它4个变形自由度有线性
的有效刚度和有效阻尼属性12-13 3 个模型分别采用 35 个铅芯橡胶隔震支座
框架结构
每个柱基础与柱之间设置一个隔震垫形成隔震支座
布置见 1 3为设置隔震支座前
后模型自振周期
2铅芯橡胶支座参数
Table 2 Parameters of leader rubber bearing
模型 支座型 参数
竖向刚度
/ kN /m 等效刚度
/ kN /m 屈服前刚度
/ kN /m 屈服后刚度
/ kN /m 屈服力/kN 等效阻尼比
/%
模型一 GZY400 1629000 1325 4647 715 41. 9 27. 2
模型二 GZY600 2614000 1859 6519 1003 94. 2 27. 2
模型三 GZY700 4065000 2531 8873 1365 128. 2 27. 2
3设置隔震支座前后模型自振周期
Table 3 The natural vibration period of before and after setting leader rubber bearing
模型 自振周期/ s
1 2 3
模型一 设置隔震支座前 0 518 0. 505 0. 468
设置隔震支座后 1 431 1. 348 1. 244
3
No. 1 贺秋梅等近断层速度脉冲型地震动作用基础隔震建筑位移反应分析
续表 3
模型 自振周期/ s
1 2 3
模型二 设置隔震支座前 1 066 1. 034 0. 962
设置隔震支座后 1 980 1. 712 1. 593
模型三 设置隔震支座前 1 477 1. 422 1. 311
设置隔震支座后 2 498 2. 465 1. 877
2基础输入地震动的选取
目前对于速度脉冲型地震动似乎没有明确
统一的定义
本文倾向于以下判断速度脉
冲的标准如果速度时程中具有急剧的
突起
并满足 1速度脉冲持时在0. 5s
2速度时程中最大峰值是第二大峰值的两倍以上 3如果有两个峰值较为接近
则二
者中峰值稍小者是其余最大峰值的两倍以上
根据速度脉冲产生的机理不同
可以将速度脉冲分为以下两类
1由于破裂传播的多普勒效应引起的方向性速度脉冲即当满足以下条件断层
破裂方向朝向场地或夹角较小 断层破裂速度接近场地剪切波速方向性效应使能
量在短时间内累积
进而引起冲击型的地面运动
反映在时程上表现为大的幅值
明显的
脉冲波形和短的地震动持时这个速度脉冲多表现为一个双向速度脉冲
2由滑冲效应引起的速度脉冲滑冲效应的产生原因是断层两盘的相对运动
面出现阶跃式的不可恢复的永久位移滑冲效应引起的速度脉冲与永久位移的大小
它主要表现在平行于断层滑动方向的分量上
呈单向
参照以上要求
本文选择6条地震动加速度记录作为脉冲型地震动记录输入
所选地
震动记录参数见表4
加速度时程与速度时程见图2.
4近断层速度脉冲型地震动记录参数
Table 4 Parameters of the near-fault ground motions with velocity pulse
产生机制 代号 震名称 震级 台站 分量 场地 持时/s
方向性效应
A1 Northridge19947. 1 Newhall-W. Pico Canyon Rd comp046 B/ C 20. 48
A2 Imperial Valley19796. 5 E07 compSN B / C 20. 48
A3 Imperial Valley19796. 5 E04 compSN B / C 20. 48
滑冲效应
B1 CHI-CHI19997. 6 TCU75 compEW D 40 96
B2 CHI-CHI19997. 6 TCU76 compEW D 40 96
B3 CHI-CHI19997. 6 TCU129 compEW D 40 96
针对每一条带有速度脉冲的实际地震动记录
根据记录的计算加速度反应谱分别拟
合反应谱合成6条人工地震动
地震动记录 A1 对应的人工地震动记为 aa11aa12
aa13aa14aa15 aa16
地震 A2 对应的人工地震动记为 aa21aa22aa23aa24
aa25 aa26
地震动记录 A3 对应的人工地震动记为 aa31aa32aa33aa34aa35 aa36
地震动记录 B1 对应的人工地震动记为 bb11bb12bb13bb14bb15 bb16
地震动记录
B2 对应的人工地震动记为 bb21bb22bb23bb24bb25 bb26
地震动记录 B3 对应的人
4应用基础与工程科学学报 Vol. 22
2速度脉冲型地震动记录加速度时程与速度时程
Fig. 2 Acceleration and velocity time histories of
the ground motions with velocity pulse
工地震动 bb31bb32bb33bb34bb35 bb36. 人工地震动加速度和速度时程的部
分样本如图3所示这些人工地震动时程不再具有速度脉冲特性
但具有相同的加速度反
应谱和相近的时程强度包络将人工地震动时程和原地震动记录一起作为输入地震动
以排除不同反应谱的影响作用而分析速度脉冲是否会对基础结构建筑地震反应产生影
从而考察近断层地震动的两类速度脉冲特性对基础隔震建筑结构位移反应的影响
差异
5
No. 1 贺秋梅等近断层速度脉冲型地震动作用基础隔震建筑位移反应分析
3人工地震动的加速度和速度时程
Fig. 3 Acceleration and velocity time histories of the artificial ground motion
3计算过程与结果分析
输入表1的各地震动时程及人工地震动时程进行结构动力反应分析
上部结构的模
态阻尼比取为0. 05 计算时X向加速度峰值分别调整为220cm / s2
相当于罕遇地震的
大小
时间步长为0. 01s
计算结构的前30 个模态基础隔震结构的非线性时程分析采用
快速非线性分析法FNA FNA 方法是一种非线性分析的有效方法
在这种方法中
非线
性被作为外部荷载处理
形成考虑非线性荷载并进行修正的模态方程
为了衡量速度脉冲对基础隔震结构位移反应的影响效果
引入位移反应脉冲影响系
其值根据基础隔震结构各层位移反应的最大值定义
kc
ij =dc
imax
dc
ij max
6应用基础与工程科学学报 Vol. 22
式中dc
ij dc
i分别为速度脉冲型地震动时程 AiBi和合成地震动 AijBij引起的
基础隔震结构第 c层的最大位移反应kc
ij 为第 c层的位移反应脉冲影响系数
计算 6组地震动作用下各模型的各层最大位移反
并计算其位移反应脉冲影响系
以模型二各层最大位移反应及脉冲影响系数计算结果为示例
见表 510 因篇幅
所限
模型一及模型三的计算结果不再一一展示
5 A1 组地震动时程作用下各层最大位移模型二
Table 5 Maximum displacement of each layer under A1 group of earthquake ground motionsmodel 2
时程 位移/cm 0 1 2 3 4 5 6 7 8 9 均值
A1 d116. 06 17 27 18. 59 19 82 20. 90 21 80 22. 52 23 06 23. 44 23 66 /
A11 d11 17. 68 18 86 20. 13 21 30 22. 32 23 18 23. 87 24 39 24. 74 24 96 /
k11 0. 91 0. 92 0. 92 0. 93 0. 94 0. 94 0 94 0. 95 0. 95 0. 95 0 93
A12 d12 16. 12 17 38 18. 76 20 03 21. 14 22 07 22. 82 23 39 23. 78 24 01 /
k12 1. 00 0. 99 0. 99 0. 99 0. 99 0. 99 0 99 0. 99 0. 99 0. 99 0 99
A13 d13 14. 23 15 31 16. 57 17 78 18. 85 19 74 20. 46 21 00 21. 37 21 59 /
k13 1. 13 1. 13 1. 12 1. 11 1. 11 1. 10 1 10 1. 10 1. 10 1. 10 1 11
A14 d14 15. 29 16 51 17. 83 19 05 20. 11 21 00 21. 72 22 26 22. 63 22 85 /
k14 1. 05 1. 05 1. 04 1. 04 1. 04 1. 04 1 04 1. 04 1. 04 1. 04 1 04
A15 d15 10. 77 11 59 12. 49 13 33 14. 07 14 69 15. 20 15 58 15. 84 16 00 /
k15 1. 49 1. 49 1. 49 1. 49 1. 49 1. 48 1 48 1. 48 1. 48 1. 48 1 48
A16 d16 12. 99 13 83 14. 74 15 58 16. 31 16 93 17. 43 17 81 18. 07 18 22 /
k16 1. 24 1. 25 1. 26 1. 27 1. 28 1. 29 1 29 1. 29 1. 30 1. 30 1 28
均值 k1. 14 1. 14 1. 14 1. 14 1. 14 1. 14 1. 14 1. 14 1 14 1. 14 1 14
归一化 k1 00 1. 00 1. 00 1 00 1. 00 1. 00 1. 00 1. 00 1 00 1. 00 /
6 A2 组地震动时程作用下各层最大位移模型二
Table 6 Maximum displacement of each layer under A2 group of earthquake ground motionsmodel 2
时程 位移/cm 0 1 2 3 4 5 6 7 8 9 均值
A2 d210. 19 10 72 11. 29 11 82 12. 29 12 68 12. 99 13 24 13. 41 13 51 /
A21 d21 6. 39 6. 97 7. 62 8 23 8. 78 9. 26 9. 64 9. 94 10. 14 10. 26 /
k21 1. 60 1. 54 1. 48 1. 44 1. 40 1. 37 1 35 1. 33 1. 32 1. 32 1 41
A22 d22 11. 23 11 97 12. 80 13 59 14. 32 14 94 15. 45 15 84 16. 11 16 27 /
k22 0. 91 0. 90 0. 88 0. 87 0. 86 0. 85 0 84 0. 84 0. 83 0. 83 0 86
A23 d23 7. 11 7 74 8. 44 9. 08 9 64 10. 11 10. 48 10 77 10 97 11 08 /
k23 1. 43 1. 38 1. 34 1. 30 1. 28 1. 25 1 24 1. 23 1. 22 1. 22 1 29
A24 d24 8. 49 9 07 9. 71 10 32 11. 02 11 62 12. 11 12 48 12. 73 12. 88 /
k24 1. 20 1. 18 1. 16 1. 15 1. 11 1. 09 1 07 1. 06 1. 05 1. 05 1 11
A25 d25 8. 77 9 41 10 11 10. 75 11 32 11. 80 12 18 12. 47 12 67 12. 79 /
k25 1. 16 1. 14 1. 12 1. 10 1. 09 1. 07 1 07 1. 06 1. 06 1. 06 1 09
A26 d26 6. 25 6. 76 7. 34 7 91 8. 45 8. 93 9. 32 9. 62 9 82 9. 94 /
k26 1. 63 1. 59 1. 54 1. 49 1. 45 1. 42 1 39 1. 38 1. 37 1. 36 1 46
均值 k1. 32 1. 29 1. 25 1. 23 1. 20 1. 18 1. 16 1. 15 1 14 1. 14 1 20
归一化 k1 16 1. 13 1. 10 1 07 1. 05 1. 03 1. 02 1. 01 1 00 1. 00 /
7
No. 1 贺秋梅等近断层速度脉冲型地震动作用基础隔震建筑位移反应分析
7 A3 组地震动时程作用下各层最大位移模型二
Table 7 Maximum displacement of each layer under A3 group of earthquake ground motionsmodel 2
时程 位移/cm 0 1 2 3 4 5 6 7 8 9 均值
A3 d311. 21 12 11 13. 27 14 34 15. 27 16 05 16. 67 17 15 17. 47 17 66 /
A31 d31 7. 73 8 47 9. 30 10 08 10. 78 11 36 11. 83 12 18 12. 43 12. 57 /
k31 1. 45 1. 43 1. 43 1. 42 1. 42 1. 41 1 41 1. 41 1. 41 1. 40 1 42
A32 d32 8. 61 9 28 10 00 10. 66 11 24 11. 73 12 12 12. 42 12 62 12. 74 /
k32 1. 30 1. 31 1. 33 1. 34 1. 36 1. 37 1 38 1. 38 1. 38 1. 39 1 35
A33 d33 7. 14 7 87 8. 69 9. 46 10 13 10. 70 11. 16 11 51 11 75 11 89 /
k33 1. 57 1. 54 1. 53 1. 52 1. 51 1. 50 1 49 1. 49 1. 49 1. 49 1 51
A34 d34 7. 54 7 97 8. 45 8. 90 9 34 9 82 10 20 10. 49 10 69 10. 81 /
k34 1. 49 1. 52 1. 57 1. 61 1. 63 1. 63 1 63 1. 63 1. 63 1. 63 1 60
A35 d35 7. 95 8 74 9. 62 10 45 11. 17 11 78 12. 27 12 64 12. 90 13. 05 /
k35 1. 41 1. 39 1. 38 1. 37 1. 37 1. 36 1 36 1. 36 1. 35 1. 35 1 37
A36 d36 10. 12 10 67 11. 27 11 86 12. 42 12 92 13. 33 13 66 13. 88 14 02 /
k36 1. 11 1. 14 1. 18 1. 21 1. 23 1. 24 1 25 1. 26 1. 26 1. 26 1 21
均值 k1. 39 1. 39 1. 40 1. 41 1. 42 1. 42 1. 42 1. 42 1 42 1. 42 1. 41
归一化 k1 00 1. 00 1. 01 1 02 1. 02 1. 02 1. 02 1. 02 1 02 1. 02 /
8 B1 组地震动时程作用下各层最大位移模型二
Table 8 Maximum displacement of each layer under B1 group of earthquake ground motionsmodel 2
时程 位移/cm 0 1 2 3 4 5 6 7 8 9 均值
B1 d116. 42 17 39 18. 46 19 46 20. 33 21 07 21. 66 22 11 22. 42 22 61 /
B11 d11 8. 28 8 92 9. 62 10. 29 10. 87 11. 37 11 78 12. 09 12 30 12. 43 /
k11 1. 98 1. 95 1. 92 1. 89 1. 87 1. 85 1 84 1. 83 1. 82 1. 82 1 88
B12 d12 16. 51 17 45 18. 47 19 42 20. 27 20 99 21. 59 22 05 22. 36 22 55 /
k12 0. 99 1. 00 1. 00 1. 00 1. 00 1. 00 1 00 1. 00 1. 00 1. 00 1 00
B13 d13 8. 65 9 29 9. 98 10. 61 11. 17 11. 63 12 00 12. 28 12 48 12. 59 /
k13 1. 90 1. 87 1. 85 1. 83 1. 82 1. 81 1 80 1. 80 1. 80 1. 80 1 83
B14 d14 11. 00 11 79 12. 65 13 44 14. 14 14 72 15. 19 15 54 15. 78 15 93 /
k14 1. 49 1. 48 1. 46 1. 45 1. 44 1. 43 1 43 1. 42 1. 42 1. 42 1 44
B15 d15 7. 16 7 84 8. 59 9 29 9 90 10 42 10. 83 11 14 11. 36 11 48 /
k15 2. 29 2. 22 2. 15 2. 09 2. 05 2. 02 2 00 1. 98 1. 97 1. 97 2 08
B16 d16 8. 85 9 56 10 33 11. 04 11 66 12. 18 12 59 12. 91 13 12 13. 25 /
k16 1. 86 1. 82 1. 79 1. 76 1. 74 1. 73 1 72 1. 71 1. 71 1. 71 1 76
均值 k1. 75 1. 72 1. 70 1. 67 1. 65 1. 64 1. 63 1. 62 1 62 1. 62 1 67
归一化 k1 08 1. 06 1. 05 1 03 1. 02 1. 01 1. 01 1. 00 1 00 1. 00 /
9 B2 组地震动时程作用下各层最大位移模型二
Table 9 Maximum displacement of each layer under B2 group of earthquake ground motionsmodel 2
时程 位移/cm 0 1 2 3 4 5 6 7 8 9 均值
B2 d24. 76 5. 26 5. 84 6. 43 6 95 7. 39 7. 75 8. 02 8. 20 8 31 /
B21 d21 5. 08 5. 51 6. 06 6 58 7. 02 7. 40 7. 71 7. 94 8. 10 8 19 /
k21 0. 94 0. 95 0. 96 0. 98 0. 99 1. 00 1 00 1. 01 1. 01 1. 01 0 99
B22 d22 5. 20 5. 75 6. 36 6 91 7. 40 7. 81 8. 14 8. 39 8. 55 8 66 /
k22 0. 92 0. 91 0. 92 0. 93 0. 94 0. 95 0 95 0. 96 0. 96 0. 96 0 94
B23 d23 5. 46 5. 78 6. 12 6 44 6. 74 7. 00 7. 23 7. 42 7. 55 7 64 /
k23 0. 87 0. 91 0. 95 1. 00 1. 03 1. 06 1 07 1. 08 1. 09 1. 09 1 01
8应用基础与工程科学学报 Vol. 22
续表 9
时程 位移/cm 0 1 2 3 4 5 6 7 8 9 均值
B24 d24 3. 86 4. 23 4. 64 5 02 5. 43 5. 85 6. 19 6. 45 6. 63 6 74 /
k24 1. 23 1. 24 1. 26 1. 28 1. 28 1. 26 1 25 1. 24 1. 24 1. 23 1 25
B25 d25 3. 85 4. 28 4. 74 5 17 5. 55 5. 87 6. 12 6. 32 6. 45 6 53 /
k25 1. 24 1. 23 1. 23 1. 24 1. 25 1. 26 1 26 1. 27 1. 27 1. 27 1 25
B26 d26 3. 06 3. 27 3. 54 3 93 4. 27 4. 55 4. 79 4. 96 5. 08 5 16 /
k26 1. 55 1. 61 1. 65 1. 64 1. 63 1. 62 1 62 1. 61 1. 61 1. 61 1 62
均值 k1. 13 1. 14 1. 16 1. 18 1. 19 1. 19 1. 19 1. 20 1 20 1. 20 1 18
归一化 k1 00 1. 01 1. 03 1 05 1. 05 1. 06 1. 06 1. 06 1 06 1. 06 /
10 B3 组地震动时程作用下各层最大位移模型二
Table 10 Maximum displacement of each layer under B3 group of earthquake ground motionsmodel 2
时程 位移/cm 0 1 2 3 4 5 6 7 8 9 均值
B3 d34. 63 5. 02 5. 46 5. 86 6 21 6. 52 6. 76 6. 95 7. 08 7 16 /
B31 d31 3. 46 3. 99 4. 61 5 19 5. 72 6. 17 6. 54 6. 81 7. 00 7 12 /
k31 1. 34 1. 26 1. 18 1. 13 1. 09 1. 06 1 03 1. 02 1. 01 1. 01 1 11
B32 d32 3. 68 3. 98 4. 30 4 77 5. 19 5. 55 5. 86 6. 10 6. 27 6 38 /
k32 1. 26 1. 26 1. 27 1. 23 1. 20 1. 17 1 15 1. 14 1. 13 1. 12 1 19
B33 d33 4. 36 4. 70 5. 10 5 48 5. 85 6. 19 6. 49 6. 81 7. 03 7 16 /
k33 1. 06 1. 07 1. 07 1. 07 1. 06 1. 05 1 04 1. 02 1. 01 1. 00 1 05
B34 d34 3. 41 3. 79 4. 21 4 60 4. 94 5. 38 5. 74 6. 01 6. 19 6 30 /
k34 1. 36 1. 32 1. 30 1. 27 1. 26 1. 21 1 18 1. 16 1. 14 1. 14 1 23
B35 d35 3. 36 3. 72 4. 17 4 60 4. 97 5. 28 5. 53 5. 72 5. 85 5 93 /
k35 1. 38 1. 35 1. 31 1. 27 1. 25 1. 23 1 22 1. 21 1. 21 1. 21 1 26
B36 d36 3. 45 3. 86 4. 32 4 75 5. 12 5. 43 5. 67 5. 86 5. 99 6 07 /
k36 1. 34 1. 30 1. 26 1. 23 1. 21 1. 20 1 19 1. 19 1. 18 1. 18 1 23
均值 k1. 29 1. 26 1. 23 1. 20 1. 18 1. 15 1. 14 1. 12 1 11 1. 11 1 18
归一化 k1 16 1. 14 1. 11 1 08 1. 06 1. 04 1. 02 1. 01 1 00 1. 00 /
3. 1 速度脉冲对基础隔震结构各层最大位移反应的影响
由表 510 可以看出
6组地震动作用下模型二的位移反应均为由隔震层开始
逐渐
顶层位移最大 6 条速度脉冲地震动的平均位移反应脉冲影响系数分别为
1. 141. 211. 411. 671. 18 1 18
以上 6条地震动时程速度脉冲影响系数的总平均值
1. 30
即在本文所选的6条速度脉冲地震动作用下模型二的位移反应比无速度脉冲人
工地震动作用下增大1. 30
同理
模型一的速度脉冲影响系数总平均值为 1 45
模型三的速度脉冲影响系数总
平均值为1. 31
由此可见
在加速度反应谱
峰值加速度
持时及强度包络函数等参数都近似相等
误差 10% 的情况下
无速度脉冲是影响基础隔震结构位移反应大小的重要因
度脉冲对结构位移反应有一定的不利影响
对于本文所选的3个模型
速度脉冲使基础隔
震结构的位移反应分别增大1. 301. 45 1 31
3. 2 两类速度脉冲对基础隔震结构各层最大位移反应的影响差异分析
为了对比两类速度脉冲对基础隔震结构位移反应的影响差异
现将两类速度脉冲地
震动分别讨论由表 510 可以看出A1A2 A3 三条向前方向性速度脉冲地震动的
9
No. 1 贺秋梅等近断层速度脉冲型地震动作用基础隔震建筑位移反应分析
位移反应脉冲影响系数均值为 1. 25B1B2 B3 三条滑移效应脉冲地震动的位移反应
脉冲影响系数均值为1. 34
因此
滑移效应速度脉冲地震动时程作用下模型二的位移反
应脉冲影响系数略大于向前方向性速度脉冲地震动时程的影响系数
略大 7%
4为两类速度脉冲地震动对模型二位移反应脉冲影响系数各层均值由图可以看
滑冲效应速度脉冲地震动作用下的各层脉冲影响系数均大于向前方向性速度脉冲地
震动作用
与上部结构相比
隔震层位移影响系数较大6条速度脉冲地震动的隔震层位
移脉冲影响系数平均值分别 1. 141. 321. 391. 721 131 29
其中3条向前方向性
速度脉冲地震动的影响系数均值为1. 28
3条滑冲效应速度脉冲地震动的影响系数均
值为 1 38
因此
滑冲效应速度脉冲对模型二的隔震层位移影响更大些
略大 8%
为了更直观地表现速度脉冲对结构各层变形的影响程度
本文中将两类速度脉冲地
震动对模型二每层10
含隔震层的平均位移反应影响系数进行
1
处理
体为
各层归1化脉冲影响系数 =该层位移反应脉冲影响系数/10 中最小位应影
响系数计算结果如图5所示从图中可以看出
两类速度脉冲对模型二位移反应的影
响均由隔震层开始逐渐减小
速度脉冲对顶部位移反应的影响最小
且对顶部34层位
移反应的影响大小相同相对于顶部的 3
滑冲效应速度脉冲对隔震层及底部3层位移
反应的影响更大一些
向前方向性速度脉冲对顶部与底部的影响差别没有滑冲效应速度
脉冲明显
综上所述
相比无速度脉冲地震动作用
速度脉冲地震动使模型二各层的位移反应明
显增大
两类速度脉冲均对隔震层位移的影响最相比向前方向性速度脉冲而言
滑冲
效应速度脉冲对该结构位移反应的影响更大
略大 7%
且对该结构底部 3层位移反应的
影响明显大于对上部结构的影响
即滑冲效应速度脉冲使得结构底部变形更大
导致结构
可能发生底部倒塌破坏
模型一的计算结果如图6和图 7所示
滑冲效应速度脉冲地震动时程的位移反应脉
冲影响系数略大于向前方向性速度脉冲地震动时程的影响系数
略大 3% 相比于顶部 3
滑冲效应速度脉冲对隔震层及底层位移反应的影响更大些
向前方向性速度脉冲对顶
01 应用基础与工程科学学报 Vol. 22
部与底部的影响差别没有滑冲效应速度脉冲明显
模型三的计算结果如图8和图 9所示
向前方向性速度脉冲地震动作用下模型三的
位移反应脉冲影响系数略大于滑移效应速度脉冲地震动
略大 7%
这一结果与前两个模
型的计算结果相反但是
滑冲效应对该结构底部4层位移反应的影响明显大于对上部结
构的影响
这一结果与模型一和模型二的结果一致
即滑冲效应速度脉冲使得结构底部变
形更大
4结论
以实际的近断层速度脉冲地震动记录和相应的人工合成的无速度脉冲地震动时程作
为地震动输入
通过对比49层和 14 3个基础隔震结构在有
无速度脉冲地震动激
励下的反应
分析了速度脉冲对基础隔震结构位移反应的影响
并详细分析了向前方向性
及滑冲效应两种不同机制引起的速度脉冲对基础隔震结构地震反应影响的差异
表明
11
No. 1 贺秋梅等近断层速度脉冲型地震动作用基础隔震建筑位移反应分析
1速度脉冲对基础隔震结构的位移反应有显著影响3个基础隔震模型在速度脉冲
型地震动激励下
位移反应均比无速度脉冲地震动大3个模型的平均位移反应脉冲影响
系数分别为1. 451 30 1 31
在近断层区域的基础隔震结构应充分考虑速度脉
冲的影响
防止构件和结构产生过得的变形而影响结构的正常使用
2两种不同机制的速度脉冲对基础隔震结构的位移反应也有差异对于 4层和 9
层基础隔震结构
滑移效应脉冲引起的位移反应略大于向前方向性速度脉冲
而对于14
层基础隔震结构
向前方向性速度脉冲对位移反应的影响更大些因此
对于中低层基础
隔震建筑的位移反应滑冲效应脉冲的影响更大一
而向前方向性速度脉冲对高层建筑
位移反应影响更大
3为了更直观地表现速度脉冲对结构各层变形的影响程度
将两类速度脉冲地震
动对模型每层的平均位移反应影响系数进行
1
处理 3 个模型的结果表
速度脉
冲对基础隔震结构的隔震层位移反应的影响明显大于对上部结构的影响
且滑冲效应速
度脉冲使得基础隔震结构底部变形更大
导致结构可能发生底层倒塌破坏
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Displacement Response Analysis of Base-isolated Buildings
Subjected to Near-fault Ground Motions with
Velocity Pulse
HE Qiumei1LI Xiaojun12YANG Yu3
1. Institute of GeophysicsChina Earthquake AdministrationBeijing 100081China2. The College of Architecture and
Civil EngineeringBeijing University of TechnologyBeijing 100022China3. Nuclear and Radiation Safety Center
Ministry of Environmental ProtectionBeijing 100082China
Abstract
In order to study the influence of the velocity pulse to seismic displacement response of
base-isolated buildings and the differences of the influent of the two types of near-fault ground
motions with velocity pulse to seismic response of base-isolated buildingsthe seismic responses
were analyzed by three dimensional finite element models for three base-isolated buildings4
stories9 stories and 14 stories. In this studycomparative analyses were done for the seismic
displacement responses of the base-isolated structures under 6 near-fault ground motion records
with velocity pulse and no velocity pulsein which6 artificial ground motion time histories with
same elastic response spectrum as the 6 near-fault ground motion records were used as the
ground motion with no velocity pulse. This study indicates that under the ground motions with
velocity pulse the seismic displacement response of base-isolated buildings is significantly
increased than the ground motions with no velocity pulse. To the median-low base-isolated
buildingsthe impact of forward directivity pulses is bigger than fling-step pulses. To the high
base-isolated buildingsthe impact of fling-step pulses is bigger than forward directivity pulses.
The fling-step pulses lead to large displacement response in the lower stories.
Keywordsnear faultvelocity pulsestrong motion recordbase-isolated building
displacement response
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No. 1 贺秋梅等近断层速度脉冲型地震动作用基础隔震建筑位移反应分析
... First, an initial acceleration time history is generated according to the target peak ground acceleration, acceleration response spectrum, and intensity envelope, using trigonometric series with an iterative procedure [40]. Then, the initial acceleration time history is further adjusted such that its peak ground velocity approaches the targeted one, which is achieved by modifying the Fourier amplitudes of the initial acceleration time history [41]. As shown in Fig. 6, the acceleration time histories aj1, aj2, and aj3 (j = 1, 2, and 3) are generated according to the acceleration response spectra of the forward-directivity pulse-like ground motions Aj. ...
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The velocity pulse of near-fault ground motions can aggravate the earthquake damage to engineering structures. The velocity pulse is regarded as one of the important engineering characteristics of near-fault ground motions affecting the earthquake damages to engineering structures. The seismic responses and structural control effects were simulated by three dimensional finite element model for long-span floating cable-stayed bridges with and without the vibration control system, in which four strong motion records with velocity pulse and corresponding synthetic time histories with same response spectra and without velocity pulse were used as ground motion inputs. The characteristics of velocity pulse influence were discussed respectively on seismic responses of long-span floating cable-stayed bridges with and without the vibration control system. The study shows that seismic responses of cable-stayed bridge to ground motions with velocity pulse are greater than those to ground motions without velocity pulse, and ground motions with velocity pulse can make strong disadvantageous influence on seismic responses of bridges with un-control, semi-active control and passive control systems, and the influence is almost same on responses of bridges with semi-active control and passive control systems.
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In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspect is the ground motions, which are usually assigned by engineers as a type of input load for seismic design of structures, sometimes can control the final design results. The experiments, performance evaluations and other related aspects are all based on the specified type of load. As a result, many aspects related to civil engineering will be influenced by changes of the type of load. Hence, the characteristics of the load and the corresponding response of structures are desired for studying. In this paper, the state-of-the-art of near-field problems in civil engineering is comprehensively reviewed, which include inherent characteristics of near-field ground motions and influences of these ground motions on civil structures. The existing problems are pointed out and work needed to be further investigated in the future is suggested. It is believed that the information in this paper can be useful to advance the state of investigation on near-field problems.