STRUCTURAL RESPONSE AND DAMAGE ASSESSMENT BY ENHANCED UNCOUPLED MODAL RESPONSE HISTORY ANALYSIS

The Uncoupled Modal Response History Analysis (UMRHA) method developed by Chopra et al. is modified in this paper to estimate damage to welded moment-resisting connections in a steel frame (MRSF) subjected to earthquake ground motions. The behaviour of these connections is modelled by a moment-rotation relationship that accounts for the cracking of the beam flange-to-column flange groove weld. The behaviour of the frame is approximated by a sequence of single-degree-of-freedom (SDOF) models for the first three modes to allow for the contribution of higher modes of vibration. The dynamic properties of these SDOF systems are determined by nonlinear static pushover analyses of the building frame. Because of the significant drop in connection strength caused by beam-to-column weld cracking, the pushover procedure uses a changing rather than invariant distribution of horizontal loads, while the structural responses are calculated from shapes that are based on the displaced shape of the frame after damage occurs. The accuracy of the method is demonstrated by a comparison with the results of a nonlinear time history analysis of the frame. This method can be used for rapid assessment of seismic damage or damage potential and to identify buildings requiring more detailed investigation.     

Methods and Challenges for the Seismic Assessment of Historic Masonry Structures

ABSTRACT

Despite the high vulnerability of historic structures to earthquakes, the approaches for evaluating seismic demand and capacity still appear inadequate and there is little consensus on the most appropriate assessment methods to use. To develop an improved knowledge on the seismic behavior of masonry structures and the reliability of analysis tools, two real-scale specimens were tested on a shake table, and several experts were invited to foresee failure mechanism and seismic capacity within a blind prediction test. Once unveiled, experimental results were simulated using multi-block dynamics, finite elements, or discrete elements. This article gathers the lessons learned and identifies issues requiring further attention. A combination of engineering judgment and numerical models may help to identify the collapse mechanism, which is as essential as it is challenging for the seismic assessment. To this purpose, discrete modeling approaches may lead to more reliable results than continuous ones. Even when the correct mechanism is identified, estimating the seismic capacity remains difficult, due to the complexity and randomness of the seismic response, and to the sensitivity of numerical tools to input variables. Simplified approaches based on rigid body dynamics, despite the considerable experience and engineering judgment required, provide as good results as do advanced simulations.     

明清徽州水旱灾害研究

本文以方志、家谱为主要资料,参考正史、档案中的相关记载,对明清以来徽州地区的水旱灾害资料系统收罗,借鉴历史灾害的等级量化方法,根据徽州区域特点制定出相应的等级划分标准,对明清以来徽州六县水旱灾害进行了分级量化的尝试,既而对量化数据进行统计分析,总结了该区域历史时期的水旱特点,并从地理微地貌的角度进行了原因探讨。     

Evaluating Ethnopedological Knowledge Systems for Classifying Soil Quality. A Case Study in Bo Hamlet with Muong People of Northern Vietnam

Ethnopedological knowledge is incorporated in a case study for sustainable land management of mountain karst areas in Vietnam. The research is based on a multidisciplinary approach, including participation of local inhabitants for identifying and classifying local indicators of soil quality, next to scientifically sound approaches to soil quality assessment based on analytical soil data and a statistical treatment of the results. The case study focuses on Bo hamlet, located in the Ngo Luong commune of the Tan Lac district, Hoa Binh province. The participatory approach reveals that local people of the Muong ethnic group distinguish seven land use types and six soil types. They also identified nine local indicators of soil quality: presence of earthworms; crop productivity; topsoil colour; presence of a humus layer; soil surface compaction; erosion; slope gradient; surface water, and soil moisture status. Based on this indigenous knowledge, 19 soil samples from nine soil profiles in Bo hamlet were analysed for fertility indicators. Laboratory results confirmed the validity of indigenous knowledge for identifying and classifying local indicators of soil fertility, compared to scientific standards of soil quality.     

Space, Time and Sustainability in the Hadejia-Jama'are Wetlands and the Komodugu Yobe Basin, Nigeria

Debates about sustainability still take insufficient account of the significance of space and time. In this paper, their significance is demonstrated empirically through an account of the complex environmental and socio-economic impacts of dam construction on flood-plain wetlands in the Hadejia-Jama'are river basin in Nigeria. Socio-economic data from a rapid rural appraisal exercise and household questionnaire survey (data on patterns of production in the flood plain and patterns of mobility) are appraised in the context of patterns of environmental change and of inundation (analysis of riparian vegetation and time-series aerial photographs). The paper concludes that sustainable river basin development requires more attention to be paid to the perspectives derived from different scales of analysis. This calls for appropriate institutions allowing communication at the interface between village-level producer and river basin manager.     

Physical Characterization,Microstructural Evaluation,and Condition Assessment of Ancient Ahlat Tombstones in the Seljukian Cemetery of Ahlat (Turkey)

A typical Seljukian town of Ahlat, located between the north-western shores of the Lake Van and the Nemrud and Suphan volcanoes of the Eastern Turkey is hosting rich and colorful cultural heritage sites. Among these, famous Seljukian Cemetery is a major archeological district with monumental tombstones (stelae). Excessive deterioration, erosion and lichen colonization can be observed in these cultural artifacts. The main objective of this study is the investigation of stones’ physical characterization and evaluation of the microstructural features. A degradation model was outlined starting with the capillary water uptake from the bottom section and lichen colonization starting from the top and covering these tombstones upto their mid sections. This article provides some information about the historical town of Ahlat and its tombstones. Some physical and microstructural characterization of the gravestones and the results of chemical and physical analysis are also presented along with some recommendations.     

Seismic vulnerability assessment of historic centers: description of a predictive method and application to the case study of scanno (Abruzzi,Italy)

ABSTRACT

In this article, a predictive model for the seismic vulnerability assessment of old Italian historic centers is presented through its direct application to a meaningful case study, the historic center of Scanno, in Abruzzi, Italy.

The proposed method is calibrated on the basis of the observations carried out on similar historic centers hit by the 2009 L’Aquila earthquake and is applied in order to provide likely damage scenarios by means of fragility curves. The method is based on the evaluation of a limited number of structural and typological parameters that can be obtained by simple and rapid inspections on buildings. In addition, it is conceived in order to provide useful information on the most effective anti-seismic strategies to be implemented on urban scale for pursuing a global mitigation of the seismic risk and for the application of suitable risk reduction policies.

The final aim of the article is to give an applicative vision of the method, by providing instructions on how to judge the features of the buildings that are influential on their seismic behavior, as well as by showing the potentiality of the method itself in providing likely damage scenarios, also with the support of GIS-based representations.     

An innovative methodology of assessing the climate change impact on cultural heritage

Climate change is expected to have a severe impact on cultural heritage in the future. This study presents the methodology developed during the FP7 project Climate for Culture, of assessing the climate change impact on collection objects in cultural heritage buildings. The main innovation lies in coupling new high resolution future climate projections with building simulation tools in order to predict future indoor climate and identify future risks in historic buildings. The case study is an intermittently heated wooden chapel in Croatia. The whole building simulation model of the chapel was validated using a newly developed method of accuracy assessment in the context of preventive conservation. Even though modeling intermittent heating induces limitations in the model, it can be used for computing of future indoor data. Future indoor climate data was assessed for possible risks of biological, mechanical, and chemical damage to painted wooden panels using the newly developed specific climate risk assessment. When using this method of damage assessment on buildings with active climate control, especially with intermittent heating, it is recommended to determine the relevant season for the damage process in order to objectively analyze results.     

Seismic Risk Assessment of New Zealand Unreinforced Masonry Churches using Statistical Procedures

ABSTRACT

The 2010–2011 Canterbury earthquake sequence provided extensive evidence of the significant seismic vulnerability of New Zealand unreinforced masonry (URM) churches. Given the high seismicity of the country, the exposure of human lives and the societal significance of ecclesiastic buildings, for both historical and religious reasons, the reduction in seismic vulnerability of this building type is of primary importance. By analyzing the seismic performance of a sample of 80 affected buildings, regression models correlating mean damage levels against ground-motion parameters were developed for observed collapse mechanisms, accounting for vulnerability modifiers whose influence was estimated via statistical procedures. Considering the homogeneity of New Zealand URM churches, the vulnerability models developed for the Canterbury region were extended to the whole country inventory, and a synthetic index was proposed to summarise damage related to several mechanisms. Territorial scale assessment of the seismic vulnerability of churches can assist emergency management efforts and facilitate the identification of priorities for more in-depth analysis of individual buildings. After proper calibration, the proposed approach can be applied to other countries with similar building heritage.