砖石古塔抗震性能评估方法及抗震加固措施研究

为了提高砖石古塔的抗震性能,针对其地震反应特点,研究了砖石古塔的抗震薄弱部位、抗震性能评估方法、评价指标以及抗震加固措施。主要研究结论为:（1）提出了采用极限承载能力与层间位移角2个指标综合评估砖石古塔的抗震性能,并通过工程实例验证了该方法的有效性。（2）提出了对穿锚杆锁定内外钢带围箍和竖向贯穿钢筋为主,聚丙烯酸脂乳液砂浆裂缝注浆为辅的砖石古塔综合抗震加固措施。（3）砖石古塔塔底截面为承载能力抗震薄弱部位,抗拉能力不足是导致塔体破坏的主要原因。（4）地震作用下,砖石古塔随着塔体层数的增加,层间位移角增大,顶层塔体为变形能力薄弱部位。该研究结果可为砖石古塔的抗震性能评估与抗震加固提供参考。     

砖石古塔的地震“修复”及动力学特征初探

汇集了 4例震裂古塔震而复合的有关历史资料。分析认为可探索用人工激震方法对开裂古塔进行修复。从震害资料看出 ,砖石古塔在地震烈度 度以上时将出现破坏。研究了砖石古塔的结构特性 ,提出了对古塔自振周期的计算公式。指出这些研究对古塔的修复、加固及抗震性能评价 ,无疑是有益的     

砖石古塔的地震"修复"及动力学特征初探

汇集了4例震裂古塔震而复合的有关历史资料。分析认为可探索用人工激震方法对开裂古塔进行修复。从震害资料看出，砖石古塔在地震烈度Ⅵ工以上时将出现破坏。研究了砖石古塔的结构性，提出了以古塔自振周期的计算公式。指出灾些研究对古塔的修复、加固及抗震性能评价，无疑是有益的。     

砖石古塔震害程度与地震烈度的对应关系研究

依据四川省汶川地震中损伤的砖石古塔统计资料,结合现场考证和资料分析,探讨了古塔震害程度与地震烈度的对应关系.研究表明,砖石古塔因结构高大、材料老化,对地震作用较为敏感;在地震烈度Ⅵ度区域,52％以上的古塔出现局部损坏,在地震烈度Ⅸ度及以上区域,75％以上的古塔完全毁坏;按照中国现行抗震设防标准,在设防烈度Ⅵ度至Ⅸ度的范围内建立砖石古塔震害程度与地震烈度的表述关系是合适的.论文针对古塔的结构特征、地震损伤状况以及文物修复的要求,提出了古塔震害的分级定义,确定了砖石古塔震害程度与地震烈度对应的参考指标.     

石结构古塔抗震性能研究

砖石古塔是我国古代劳动人们智慧的结晶,是研究古代建筑设计和抗震意识重要的佐证.本文介绍了石结构古塔的抗震历史,通过对古塔的基础、结构设计进行分析,结合脉动测试、爆破监测数据分析古塔的结构特性,并对古塔的抗震性能进行验算,揭示了几百年来古塔抵御强震的奥秘.     

福建泉州古石塔结构动力特性测试与分析

采用中国地震局工程力学研究所研制的SLJ-100型三分向力平衡加速度计,进行泉州东、西塔结构脉动反应测试和模态分析,可为同类古塔的测试和研究提供参考;提出了砖石古塔自振周期的计算公式,可为砖石古塔的抗震计算、鉴定及抗震加固提供一定的参考依据.     

砖石古塔基本周期的简化计算方法

古塔的自振周期是古塔损伤程度评价和抗震分析的重要参数。本文依据结构动力学基本理论和古塔动力特性实测数据,以砌体的材料性能、塔身厚度、塔身截面形状、塔身开洞率等关键参数为指标,通过古塔基本周期的理论分析和计算机模拟,提出了基于弯曲悬臂杆模型的四系数简化计算公式。按照该公式对14座典型砖石古塔的基本周期进行了计算,并与现场实测值做了对比,表明该公式计算精度满足工程要求,可用于多种类型砖石古塔的动力特性估算。     

基于脉动试验的砖石古塔抗震能力评估方法

由于古建筑具有与现代建筑不同的特点,所以基于传统抗震理论的单体建筑物抗震能力评估方法对古建筑往往难以适用;在脉动测试的基础上,对一砖石古塔抗震能力做了评估;结果表明,采用结合结构物脉动试验的抗震能力评估方法,可以对没有原始资料且已有一定损伤的砖石古塔的抗震能力做出较为合理的评估。     

窗户孔洞对砖石古塔地震反应的影响

以四川省都江堰奎光塔为工程背景,采用ANSYS软件建立实体有限元模型,应用时程反应分析法分析窗户孔洞对砖石古塔塔身控制截面应力分布规律,揭示该塔在2008年汶川地震中的震害机理。结果表明:塔身10层顶(塔身双层与单层的转换处)与1层顶为主塔抗震薄弱部位。砖石古塔窗孔附近区域应力集中现象较为突出,墙体外缘的最大、最小主应力都明显高于墙体内缘,靠近窗户附近区域的应力约为远离窗户处应力的2~3倍。在垂直于地震激励方向的主塔对称轴截面上,在窗顶出现较明显的剪应力集中,因此强震时窗顶为抗震薄弱部位。     

嵌筋加固古砖塔的偏心受压抗震验算方法

针对嵌筋加固古砖塔的配筋构造和结构性能,依据配筋砌体结构的力学原理,提出了古塔偏心受压抗震验算方法。考虑古塔的尺度、材料性能以及嵌筋工艺的特征,给出了抗震验算方法的基本假定,确定了附加偏心距、承载力抗震调整系数的取值。基于工程应用,建立了古塔矩形、圆形截面的抗震验算公式,对六边形和八边形的古塔截面,给出了简化为矩形或圆形截面的几何方法。     

基于ECC的小雁塔抗震加固性能分析

高延性纤维增强水泥基复合材料(ECC)是一种高强度、高延性的新型建筑材料,在加固工程中具有广泛的应用前景。本文利用ECC的高延性和抗剪性,提出一种采用ECC面层加固小雁塔的保护方案,以提高古塔抗震性能;通过有限元软件ANSYS进行模拟分析,比较了小雁塔加固前后的地震响应。分析结果表明:采用ECC面层加固可显著增强塔身整体的延性和承载力,有效地提高塔体损伤容限,为ECC在古塔抗震加固的实际应用中提供借鉴,可作为古塔抗震保护的新途径。     

银川海宝塔动力特性测试及抗震性能分析

为了给银川市海宝塔的修缮保护工作提供参考依据,对其动力特性及结构损伤状况开展测试和数值模拟分析。首先对海宝塔的材料强度进行测试和计算,得出塔砌体的抗压强度及弹性模量;然后对该塔进行环境激励作用下的振动响应测试,得到塔东西和南北方向的1阶频率;最后建立数值模型并分析其模态与抗震性能,得到海宝塔的动力特性与地震作用下塔体各层的层间位移角,并基于砖石古塔破坏状态位移准则以及损伤指标开展损伤分析。结果表明：海宝塔东西方向和南北方向的1阶频率较为接近,但不同楼层的振动频谱曲线差异较大,尤其是峰值点数量;楼层越高,最大位移和层间位移角越大,受损也越严重;结构总体刚度退化较为严重,存在较大安全隐患,需进一步开展深入分析并采取保护措施。     

Seismic assessment of two multi-tiered pagodas damaged by the 2015 Nepal earthquake

A seismic assessment of two multi-tier pagodas by numerical analysis is presented herein.The Changu Narayan temple and the Kumbeshwar temple in Nepal are used as the case studies.Both pagodas are built of brick masonry in earthen mortar,with timber columns and crossbeams.The Changu Narayan temple is a two-tier pagoda,and was seriously damaged during the 2015 Gorkha earthquake.The Kumbeshwar temple is a five-tier pagoda,and its top-tier collapsed due to the Gorkha earthquake.A seismic assessment was carried out using finite element(FE)analysis.The FE models were prepared,and dynamic identification tests and penetrometer tests were conducted.Pushover analysis and nonlinear dynamic analysis were performed as part of the seismic assessment.The main shock of the 2015 Gorkha earthquake was considered as the input accelerograms.The behavior between the two pagodas was compared with the collapse mechanisms and damage patterns observed in the actual structures.The comparison suggested common structural features of multi-tier pagodas.This study is dedicated to providing a better understanding of the seismic behavior of multi-tier pagoda-type structures and provides suggestions for their effective analysis.     

Evaluation of the seismic response of stone pagodas using centrifuge model tests

This study attempts to propose dynamic centrifuge model tests as a method of seismic risk assessment in order to discover how stone architectural heritages with masonry structures have endured seismic load, and whether there is any possibility of future earthquake damage. Dynamic centrifuge tests have been conducted for one fifteenth scale models of Seok-ga-tap and the five-storey stone pagoda of Jeongnimsa temple site, which are Korean representative stone pagodas. In order to make input motions of the earthquake simulator, site investigation and site-specific response analysis have been performed. The models of two stone pagodas, which have the same number of pieces with the real structures, have been produced and the dynamic centrifuge tests have been conducted for the model pagodas. Accelerometers were attached at different heights of the pagoda. The measured acceleration records and frequency responses were analysed during dynamic centrifuge test. Two real earthquake records, Hachinohe and Ofunato earthquakes and a sweeping signal with ranged frequency were utilised for input motions of dynamic centrifuge tests to evaluate the behaviour of the stone pagodas. For Seok-ga-tap models, it was observed that acceleration tends to be amplified with height. The third floor body shows at most 2.5 amplification of acceleration in comparison to the surface ground. The amplification was at a frequency of 3.83 Hz and it was considered as the natural frequency of the pagoda. For the five-storey stone pagoda, the seismic wave energy significantly reduced while it passed the first body floor, and then the peak acceleration was gradually amplified upwards. It was found that the pagodas did not collapse when the peak acceleration of ground surface was raised to 0.4 g. Given that the maximum design seismic acceleration specified in Korean seismic design guide is 0.22 g and the amplification ratio of peak acceleration in the supporting ground of the pagodas ranges from 1.45 to 1.74, it can be shown that the two pagodas are stable against 2400-year return period earthquake level, and have excellent seismic performance.     

单体建筑无筋砌体加固体系的抗震韧性研究

单体建筑无筋砌体结构的抗震韧性较差,在地震中容易发生严重破坏和倒塌。为此,以抗震韧性为参数指标,对单体无筋砌体结构进行加固并分析,研究其在地震作用下的抗震能力。以某实际工程作为研究对象,运用ANSYS软件建立单体建筑无筋砌体加固有限元模型,选取中国汶川地震波、日本阪神大地震波、美国克恩县地震波、中国台湾集集地震波及人工地震波作为地震动输入,利用韧性指数法和韧性等级法,从无筋砌体加固体系在震后的修复费用、修复时间及人员伤亡等方面进行分析,得到抗震韧性评估结果。研究表明：(1)在罕遇地震、设防地震和多遇地震的情况下,单体建筑无筋砌体结构的层间位移、层间剪应力、破坏程度均大于单体建筑无筋砌体加固体系;(2)在受到地震强弱因素影响下,无筋砌体结构的抗震韧性指数最高为0.877,而其加固体系的抗震韧性指数最低为0.908;(3)在经历不同地震波后,无筋砌体结构受到较大损害等级占比较高,人员伤亡较重,需要花费较长的时间和较多的费用完成灾后重建;而经过加固后的无筋砌体结构,加固体系受到较小损害等级占比较高,人员伤亡较轻,且能够用较短的时间和较少的费用完成灾后重建。     

混凝土多孔砖和组合配筋砖小截面墙体抗震性能的试验研究

针对农村窗间墙过窄的现状,提出一种组合配筋砌体以抵抗地震剪力,并提出混凝土多孔砖组合配筋砌体的参考公式.通过对混凝土多孔砖和组合配筋砖小截面墙体进行反复荷载下的抗震性能试验研究,讨论两种不同类型砌体的破坏特征、滞回特性、骨架曲线和抗剪强度等问题.组合配筋砌体与无筋砌体相比,抗震性能明显提高,延性增强.结果表明组合配筋砌体是一种能够明显改善小截面墙体抗震性能的实用方法,可在农村地区推广.     

砌体结构在2008汶川大地震中的震害经验

本文首先列举了砌体结构在2008汶川大地震中的典型震害现象,通过这些现象分析了此次地震中砌体结构的震害特点,归纳了其震害规律和教训,总结了必须坚持的抗震原则及对今后砌体结构抗震设计的启示,同时,探讨了几个应该注意的重点抗震问题,提出了进一步加强砌体结构抗震性能的建议。文中指出,砌体结构只要坚持正确的抗震理念,加强构造措施,落实抗震规范的设计要求,保证施工质量,就能达到相应的抗震设防目标。     

Seismic test of a full‐scale model of a five‐storey stone pagoda

A moderate size earthquake of magnitude 5 occurred at Whagae‐Myun, Hadong‐Gun, Kyongsangnam‐Do, Korea on 4 July 1936. It caused severe damage to the buildings and other structures in Sang‐Gye‐Sa, a famous and beautiful Buddhist temple. A five‐storey stone pagoda was standing in front of Keumdang, the main building. The top component of the pagoda was tipped over and fell down to the ground during the earthquake. In order to have a quantitative estimate of the intensity of the earthquake, a full‐scale model was constructed through a rigorous verification process. The completed model was mounted on a shaking table and subjected to two kinds of dynamic test: exploratory test and fragility test. The exploratory test was performed with low intensity shaking. In the fragility test, the failure modes of the model were investigated while increasing the shaking intensity. The construction details of the model are described and test procedures are reported. Important relations between failure modes and characteristics of ground motion were obtained from the tests. The intensity of the 1936 earthquake was estimated from the examination of test results. Copyright © 2003 John Wiley & Sons, Ltd.