Effects of supplemental viscous damping on seismic response of asymmetric-plan systems     

Rakesh K. Goel 《地震工程与结构动力学》1998,27(2):125-141

Coupling between lateral and torsional motions may lead to much larger edge deformations in asymmetric-plan systems compared to systems with a symmetric plan. Supplemental viscous damping has been found to be effective in reducing deformations in the symmetric-plan system. This investigation examined how supplemental damping affects the edge deformations in asymmetric-plan systems. First, the parameters that characterize supplemental viscous damping and its plan-wise distribution were identified, and then the effects of these parameters on edge deformations were investigated. It was found that supplemental damping reduces edge deformations and that reductions by a factor of up three are feasible with proper selection of system parameters. Furthermore, viscous damping may be used to reduce edge deformations in asymmetric-plan systems to levels equal to or smaller than those in the corresponding symmetric-plan system. © 1998 John Wiley & Sons, Ltd.  相似文献   

一座钢筋混凝土框架多层厂房楼面的减振加固     

沈朝勇  周福霖  谭平  罗学海  任珉  黄襄云  陈建秋  杨泽群 《世界地震工程》2005,21(2):7-12

通过现场实测,根据实测结果分析了受动荷载作用的钢筋混凝土多层框架结构厂房楼面产生较大竖向振幅的原因,对其进行了结构加固设计,包括对楼面结构主梁、次梁、楼板及下一层柱子的加固处理,根据施工完毕后的实测结果分析,楼面竖向振动幅度大大降低,达到了减振的目的。  相似文献   

Improving integrity of RC beam-column joints with deficient beam rebar anchorage     

Syafri Wardi  Yasushi Sanada  Nandita Saha  Susumu Takahashi 《地震工程与结构动力学》2020,49(3):234-260

In recent earthquakes in developing countries, severe damage was observed on reinforced concrete buildings. This study focuses on exterior beam-column joints with substandard beam rebar anchorage and seismic strengthening by installing wing walls. First, a series of experiments was conducted to investigate the seismic behavior of exterior joints with substandard beam rebar anchorage representing typical Bangladeshi buildings. Two 0.7-scaled exterior joint specimens were tested, and these specimens showed beam rebar anchorage failure and/or joint shear failure. Prior to strengthening of the joint, a series of pullout tests was conducted on postinstalled bonded anchors in low-strength concrete for strengthening design. Then, an experiment was performed to apply the strengthening method by wing walls to one of the exterior joint specimens to improve the integrity, and this method was intended to prevent the failure of beam rebar anchorage. The strengthening method is proposed to extend the development length of beam longitudinal bars by considering the embedment length along the wing walls. The test results verified the effectiveness and applicability of the proposed strengthening method to upgrade exterior RC beam-column joints with deficient beam rebar anchorage.  相似文献   

酚羟基从乙酰基保护到苄基保护的一锅法转换     

张华  李英霞  朱石磊 《中国海洋大学学报(自然科学版)》2005,35(4):626-628

在Lemieux方法的基础上,将应用于糖类化合物的方法首次应用到酚类化合物上,报道了乙酰基保护的酚类化合物,在苄溴、氢氧化钾作用下于四氢呋喃中回流通过一锅转化法转换得到苄基保护化合物;在有多个乙酰基同时存在条件下,通过调节氢氧化钾的用量来控制苄基取代的程度。该方法操作简便,收率较高。  相似文献   

半叶马尾藻多糖对辐射损伤小鼠骨髓细胞集落生成的影响   总被引：3，自引：0，他引：3  

孟庆勇  刘志辉  郑辉 《中国海洋大学学报(自然科学版)》2005,35(3):503-506

探讨半叶马尾藻多糖[Sargassum hemiphyllum(Turner)C．Ag．polysaccharides,SHP]对辐射损伤小鼠骨髓细胞集落生成的影响。检测辐射损伤小鼠脾集落生成单位、红细胞集落生成单位、爆裂型红细胞集落生成单位、粒细胞．巨噬细胞集落生成单位、巨核细胞集落生成单位、混合集落生成单位的变化。5Gy7射线照射后小鼠CFU-S,CFU—E,BFU—E和CFU—Mix明显减少,而SHP(20mg／kg-40mg／kg)可以抑制CFU—S,CFU—E,BFU—E和CFU—Mix下降。辐射损伤也可以引起小鼠CFU-GM显著降低,但是,SHP(10mg／kg-40mg／kg)具有拮抗辐射损伤的作用,使CFU-GM增加。单纯照射组小鼠CFU—Meg显著低于正常对照组,SHP(40mg／kg)加照射组小鼠CFU-Meg却显著高于单纯照射组。SHP对辐射损伤小鼠多能干细胞和造血祖细胞具有保护作用。  相似文献   

外源NO对野生早熟禾幼苗抗寒性的影响     

陈润娟  雷娅伟  白小明  田彦锋 《中国沙漠》2017,37(6):1171-1179

以野生草地早熟禾（Poa pratensis）和硬质早熟禾（Poa sphondylodes）为材料,通过人工室内模拟低温逆境胁迫,研究外源一氧化氮（NO）供体亚硝基铁氰化钠（硝普钠,SNP）对低温胁迫下野生早熟禾幼苗生长、渗透调节和抗氧化系统的影响,探讨外源NO提高早熟禾抗寒性的生理机制。结果表明,低温胁迫下：0~700 μmol·L^-1浓度范围内,随SNP浓度的增大,两个供试材料的地上生物量和生长速度先增大后减小,相对膜透性、丙二醛（MDA）含量、游离脯氨酸（F-Pro）含量先减小后增大,可溶性糖（SS）和可溶性蛋白（SP）含量先增加后减小,超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性先增强后减弱;高浓度NO产生伤害,低浓度NO则有保护作用;SNP浓度100 μmol·L^-1时,膜脂过氧化水平最低,渗透调节物质积累最多,保护酶活性最强,对低温胁迫的缓解效果最佳。硬质早熟禾对低温胁迫下外源NO的缓解较草地早熟禾敏感。  相似文献   

Seismic performance of masonry walls retrofitted with steel reinforced grout          下载免费PDF全文

Stefano De Santis  Paolo Casadei  Gerardo De Canio  Gianmarco de Felice  Marialaura Malena  Marialuisa Mongelli  Ivan Roselli 《地震工程与结构动力学》2016,45(2):229-251

An innovative solution for the seismic protection of existing masonry structures is proposed and investigated through shake table tests on a natural scale wall assemblage. After a former test series carried out without reinforcement, the specimen was retrofitted using Steel Reinforced Grout. The strengthening system comprises horizontal strips of ultra‐high strength steel cords, externally bonded to the masonry with hydraulic lime mortar, and connectors to transversal walls, applied within the thickness of the plaster layer. In order to assess the seismic performance of the retrofitted wall, natural accelerograms were applied with increasing intensity up to failure. Test results provide a deep understanding of the effectiveness of mortar‐based composites for improving the out‐of‐plane seismic capacity of masonry walls, in comparison with traditional reinforcements with steel tie‐bars. The structural implications of the proposed solution in terms of dynamic properties and damage development under earthquake loads are also discussed.Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

准东石油基地幼儿园抗震鉴定与加固     

孙静  谭明  王本华 《内陆地震》2014,28(3):219-226

结合准东石油基地幼儿园的抗震鉴定与加固实例,在对原结构抗震措施鉴定和分析验算的基础上,介绍了房屋结构薄弱部位的加固做法。对类似项目的结构加固有一定的参考价值。  相似文献   

天津市典型老旧民居抗震能力分析     

姚新强  陈宇坤  杨绪连  高武平 《震灾防御技术》2014,9(2):280-288

本文对天津市典型老旧民居进行了抗震能力分析,介绍了它们的结构形式,抗震性能。并根据相应的规范和标准,对其中一幢民居楼进行了抗震能力分析和鉴定。研究表明,在遭受Ⅶ度小震时,顶层中等破坏;Ⅷ度中震时,顶层严重破坏;Ⅸ度大震时,顶层倒塌。建议尽快进行抗震加固。本文指出了抗震薄弱环节,并给出了抗震加固措施。本文可为天津市典型老旧民居的抗震加固提供科学依据和技术支持。  相似文献   

和田地区红柳大芸冻害调查研究     

艾尼瓦尔·依沙木丁  阿不都艾尼·买斯地克 《沙漠与绿洲气象(新疆气象)》2010,4(3):52-54

2008年年初的低温、连阴降雪、冰冻天气使和田地区各县(市)的红柳大芸受到不同程度的冻害。通过对和田地区红柳大芸冻害情况进行调查分析,提出科学的接种深度和灌溉管理以及应采取的防护措施。  相似文献