外文原文出处: NATO Science for Peace and Security Series C: Environmental Security, 2009, Increasing Seismic Safety by Combining Engineering Technologies and Seismological Data, Pages 147-149
动力性能对建筑物的破坏
引言：建筑物在地震的作用下，和一些薄弱的建筑结构中，动力学性能扮演了一个很重要的角色。特别是要满足最基本的震动周期，无论是在设计的新建筑，或者是评估已经有的建筑，使他们可以了解地震的影响。
许多标准(例如：欧标，2003；欧标，2006)，建议用简单的表达式来表达一个建筑物的高度和他的基本周期。这样的表达式被牢记在心，得出标定设计(高尔和乔谱拉人，1997)，从而人为的低估了标准周期。因为这个原因，他们通常提供比较低的设计标准当与那些把设计基础标准牢记在心的人(例：乔普拉本和高尔，2000)。当后者从已进行仔细建立的数字模型中得到数值(例：克劳利普和皮诺，2004；普里斯特利权威，2007)。当数字估计与周围震动测量的实验结果相比较，有大的差异，提供非常低的周期标准(例：纳瓦洛苏达权威，2004)。一个概述不同的方式比较确切的结果刊登在马西和马里奥(2008)；另外，一个高级的表达式来指定更有说服力的坚固建筑类型，提出了更加准确的结构参数表(建筑高度，开裂，空隙填实，等等)。
联系基础和上层建筑的震动周期可能发生共振的效果。这个原因对于他们的振动，可能建筑物和土地在非线性运动下受到到破坏，这个必须被重视。通常，结构工程师和岩土工程师有不同的观点在共振作用和一些变化的地震活动。结构工程师们认为尽管建筑物和土壤的自振周期和地震周期都非常的接近。但对于建筑物周期而言，到底是因为结构还是非结构造成的破坏提出了疑问。如果加大振动，建筑物减轻自身的重量对共振产生的破坏有很大的减轻效果。岩土工程的工程师们还没有完全同意这个观点，因为土壤可以提高自身的振动周期，与建筑物有相同的振动周期，从而建立了产生共振的条件。这个问题的处理在于这个增加量到底是多少？一般来说这种答案是不可能的，因为它取决于建筑类型和土壤类型。例如，一些普通的混凝土建筑物，对这建筑物增加一个非常大的震动周期，可以知道在平常的振动下就会迅速的遭到破坏，尤其是那些砌体建筑，比如，马雪凯利建筑(2004)和克劳福建筑(2006)。
最后，估计在改装或者加固后参数表数字的变化，通过计算机计算来改变标准的振动周期，阻尼因数和振动波形。这可以是一个非常好的评估工具对于存在的一些干扰(法拉斯等，2008)。这种效果也可以作为一种诊断工具，对周围的振动测量很有帮助(布丁和汉斯，2008)。
对以上问题的进一步研究，强烈要求建立更加宽广的原地实验或者是实验室实验，得出实验结果来估算。用一个经济实用的方式，来营造动态特性。
Role of Dynamic Properties on Building Vulnerability NATO Science for Peace and Security Series C: Environmental Security, 2009, Increasing Seismic Safety by Combining Engineering Technologies and Seismological Data, Pages 147-149 Introduction Dynamic properties have a major role on the seismic behavior and vulnerability of building structures.Particularly, fundamental periods of vibration are needed, both in design of new buildings and in aement of existing ones, so that their seismic response can be evaluated.Several codes (e.g.CEN, 2003; NZSEE, 2006) recommend empirical simplified expreions between the height of a building type and its fundamental period.Such expreions were calibrated keeping in mind a force-based design (Goel and Chopra, 1997), thus intentionally aim at underestimating period values.For this reason they usually provide rather low values when compared to those ones obtained keeping in mind a displacement-based design (see e.g.Chopra and Goel, 2000), also when the latter were obtained from numerical simulations performed on carefully set up models (see e.g.Crowley and Pinho, 2004; Priestley et al., 2007).Even larger differences appear when numerical estimates are compared to experimental results based on ambient vibration measurements that provide very low period values (see e.g.Navarro et al., 2004).An overview of the different approaches together with a comparison of the relevant results is reported in Masi and Vona (2008); further, period-height expreions for some reinforced concrete building types are given, where the role of important structural characteristics (building height, cracking, masonry infills, elevation irregularities, etc.) is carefully taken into account.
Coupling between soil and building fundamental periods of vibration may cause resonance effects.For this reason also their variation, as a consequence of poible building damage and/or soil non linear behavior during the motion, needs to be considered.Typically, structural and geotechnical engineers have different points of view about resonance effect and its variation during a seismic motion.Structural engineers say that whereas building and soil have initially close periods and an earthquake occurs, the building period, as a result of structural and non structural damage, is expected to increase during the motion, so that the building “hides” itself reducing the heaviest effects of resonance.Geotechnical engineers do not completely agree with this opinion saying that also the soil period can shift towards higher values, that is in the same direction of the building one, thus the resonance condition could arise again.The question to be dealt with is: how much is the relative amount of that increase? A general answer is not poible, as it depends on building and soil type.For example, in case of reinforced concrete buildings with masonry infill, a very large increase of the building period can be expected with the level of shaking due to cracking of structural members and, particularly, of brittle masonry infill, see e.g.Mucciarelli et al.(2004), Calvi et al.(2006).Finally, estimating the variation of the dynamic characteristics after retrofitting or strengthening interventions, by computing the modified values of fundamental periods, damping factors and mode shapes, can be a practical tool to evaluate the effectivene of the intervention (Farsi et al., 2008).To this purpose and also as a diagnosis tool, ambient vibration measurements can be very helpful (Boutin and Hans, 2008).All the above questions strongly require that further studies as well wide in-situ and laboratory experimental campaigns are carried out to set up procedures able to evaluate, in a reliable as well not expensive way, building dynamic properties.
