SEISMIC HAZARD ASSESSMENT OF UNITED ARAB EMIRATES AND ITS SURROUNDINGS

This paper presents the seismic hazard assessment and seismic zoning of the United Arab Emirates (UAE) and its surroundings based on the probabilistic approach. The area that has been studied lies between 50°E-60°E and 20°N-30°N and spans several Gulf countries. First, the tectonics of the area and its surroundings is reviewed. An updated catalogue, containing both historical and instrumental events is used. Seismic source regions are modelled and relationships between earthquake magnitude and earthquake frequency is established. A modified attenuation relation for Zagros region is adopted. Seismic hazard assessment is then carried out for 20 km interval grid points. Seismic hazard maps of the studied area based on probable Peak Ground Acceleration (PGA) for 10% probability of exceedance for time-spans of 50, 100 and 200 years are shown. A seismic zone map is also shown for a 475-year return period. Although the results of the seismic hazard assessment indicated that UAE has moderate to low seismic hazard levels, nevertheless high seismic activities in the northern part of UAE warrant attention. The northern Emirates region is the most seismically active part of UAE. The PGA on bedrock in this region ranges between 0.22 g for a return period of 475 years to 0.38 g for a return period of 1900 years. This magnitude of PGA, together with amplification from local site effect, can cause structural damage to key structures and lifeline systems.     

Seismic Hazard Analysis Using Discrete Faults in Northwestern Pakistan: Part II – Results of Seismic Hazard Analysis

This article is the second of two companion articles that evaluate seismic hazard in northwestern (NW) Pakistan. Using the properties and characteristics of discrete faults in NW Pakistan described in the first article, probabilistic and deterministic seismic hazard analyses for 11 major cities in NW Pakistan were conducted. The results from both probabilistic and deterministic seismic hazard analyses exhibit good agreement. Median deterministic spectra compare favorably with uniform hazard spectra (UHS) for 475- or 975-year return periods, while the 84^th-percentile deterministic spectra compare favorably with the UHS for a 2475-year return period. Peak ground accelerations (PGAs) for 2475-year return periods exceed 1.0 g for the cities of Kaghan and Muzaffarabad, which are surrounded by major faults. The PGAs for a 475-year return period for these cities are approximately 0.6g — 3 to 4 times greater than estimates by previous studies using diffuse areal source zones. The PGAs for some cities located farther from faults (including Astor, Malakand, Mangla, Peshawar, and Talagang) are similar to those predicted using diffuse areal source zones. Seismic hazard maps for PGA and spectral accelerations at periods of 0.2 s and 1.0 s corresponding to three return period (2475, 975, and 475 years) were produced. Based on deaggregation results, a discussion of the conditional mean spectra for engineering applications is presented.     

SEISMIC ENERGY DEMAND IN STEEL MOMENT FRAMES

The present paper investigates the seismic energy demand in steel moment-resisting frames. The frames, with 3, 6 and 10 storeys, and 4 and 8 spans, are designed according to current seismic code provisions. The energy response (energy quantities and their distributions) in the frames subjected to an ensemble of six earthquake ground motions recorded on different soil conditions, is investigated by nonlinear time history analysis. The study concludes that (1) the results of energy response can be developed into a rational method of seismic evaluation and design for steel moment-resisting frames; (2) the energy concept based on the single-degree-of-freedom has limitations when extended to the realistic structural system for design purposes; and (3) it is necessary to develop the energy-based approach for seismic evaluation and design based on the seismic response of a realistic multi-degree-of-freedom structural system.     

A LOGIC TREE EXTENSION OF THE CAPACITY SPECTRUM METHOD DEVELOPED TO ESTIMATE SEISMIC RISK IN OSLO,NORWAY

The city of Oslo, Norway, was affected by a magnitude 5.4 earthquake in 1904 causing widespread minor damage. The earthquake occurred around 100 km south of Oslo within the Permean rift structure that runs North-South along the Oslofjord, and deep clay deposits under the city contributed to the damages. A seismic risk scenario including soil amplification and buildings classifications has been conducted with two earthquake sources, one very close to the city and one near the 1904 epicenter. Both scenarios exhibit strong dependencies on the soft clays underlying large parts of Oslo. The results confirm the 1904 effects, but also show a strong dependency on the applied attenuation functions. All computations are based on the capacity-spectrum method, and the predefined pushover curves and vulnerability functions were adopted from the HAZUS code. With this basis, the computational scheme was developed independent from the GIS framework, and a weighted logic tree formulation was implemented for appropriate treatment of epistemic uncertainties.     

EARTHQUAKE DAMAGE SCENARIOS AND SEISMIC HAZARD OF MESSINA,NORTH-EASTERN SICILY (ITALY) AS INFERRED FROM HISTORICAL DATA

A study aimed at evaluating earthquake damage scenarios and seismic hazard of Messina using historical data, is presented. The analysis of coeval reports allowed us to reconstruct the seismic history of the city and to obtain a homogeneous earthquake site catalogue based on intensity assessed by the European Macroseismic Scale 1998. In the last 1200 years Messina was destroyed once (1908, intensity X-XI EMS) and suffered effects estimated between intensities VII and IX EMS many times (e.g. 853, 1169, 1494, 1509, 1599, 1693, 1783, 1894, 1909). Destruction or severe damage which affected the city are mainly related to earthquakes occurring in the Messina Straits and Southern Calabria, while slighter, moderate effects are usually due to shocks taking place in the seismogenic sources of SE Sicily, Gulf of Patti and Northern Calabria. The damage scenarios of the most relevant events, delineated using coeval urban plans of the city, showed that damage distribution is strongly conditioned by the different soil response. A probabilistic seismic hazard assessment was obtained by using site observed intensities: The expected intensity in a time span of 50 years (i.e. maximum intensity characterised by at least 10% exceedance probability in 50 years) is DC EMS; the expected intensity in a time span of 300 years (10% exceedance probability in 300 years) is X EMS.     

ESTIMATION OF NEAR-SOURCE GROUND MOTION AND SEISMIC BEHAVIOUR OF RC FRAMED STRUCTURES DAMAGED BY THE 1999 ATHENS EARTHQUAKE

On September 7, 1999 an earthquake with magnitude M _W =5.9 occurred close to the city of Athens in Greece. More than 80 buildings collapsed, about 150 deaths and hundreds of injuries were reported. Soon after the event a damage investigation was carried out by two of the authors in the most heavily struck areas. The most serious damages were observed in the northern suburbs of Athens, where reinforced concrete frames and masonry buildings represent the prevalent construction systems. The hysteretic energy demands imposed on RC buildings should have been rather severe considering the structural systems characteristics and the inadequate construction details. However, over-strengths, redundancy and especially the presence of infill walls, provided a significant increase of the seismic capacity and contributed to the survival of many buildings.

The objective of the present work is to reproduce and analyse the response of typical RC frames subjected to the 1999 Athens earthquake in areas where the observed damage was particularly severe but no recordings of the ground motion were available. After a general overview of the seismotectonic environment, seismological data, observed macro-seismic intensities, structural typologies and observed building behaviour, an attempt is made to identify representative excitations in the meizoseismal area. Specifically, the required accelerograms are obtained by modifying available records so as to reproduce a given global energy content and to be consistent with the observed damage. To study the seismic response of RC models, the obtained accelerograms are used to perform nonlinear dynamic analyses.     

LOS ANGELES AFTER THE STORM: THE DIALECTIC OF ORDINARY DISASTER

This article weighs recent scientific evidence that the urbanization of Southern California has taken place during one of the most unusual episodes of climatic and seismic benignity in the last 3500 years. Official disaster and resource planning, moreover, has been based on record-keeping shorter than the temporal wavelengths of the most important landscape processes. Indeed, the “biblical” flood, fire, and earthquake disasters of the last three years may only be a prelude to seismic and climatic events of far greater magnitude. What will be the future of the Los Angeles area if Congress refuses to continue federal disaster subsidies?     

高速铁路对湖南城市群可达性的影响

引入可达性的概念,以现阶段与预期2030年的湖南城市群综合铁路网数据为基础,选取加权平均旅行时间、经济潜力和日常可达性3个度量指标,比较分析了高速铁路的发展对湖南城市群城际间8城市可达性的影响。结果表明:高速铁路大大缩短了城际之间的时空距离,将全面提升湖南区域可达性水平,促进区域均衡化空间结构的形成;另一方面,尽管高速铁路将推动多中心空间结构的形成,但对湖南城市可达性水平的影响具有明显的区域差异,可分为两个层级,各城市在新的交通格局下应抓住机遇,探寻符合自身特点的发展道路。     

Exploring international film festivals from a co-evolutionary perspective: the cases of Berlin and Busan compared

In the past two decades, the number of international film festivals strongly increased. As a research topic, however, these festivals have received little attention within economic geography and regional studies. The aim of this comparative paper is to explore the institutional history and impact on local economic development of two international film festivals, namely Berlin and Busan, from a co-evolutionary perspective. Based on qualitative empirical fieldwork done in Busan and Berlin we draw two conclusions. First, different institutional structures have led to different ways of success. However, Busan’s less stable and tenser institutional configuration may negatively affect the festival in the near future. Secondly, in both cities the festival affects the local economy, albeit in different ways.     

Seismic Assessment of the Lima Cathedral Bell Towers via Kinematic and Nonlinear Static Pushover Analyses

ABSTRACT

The protection of cultural heritage against earthquake induced actions is one of the main challenges the earthquake engineering science and practice are facing. This article presents a seismic assessment study on one of the most ancient colonial buildings present in Peru, the Cathedral of Lima, focusing on its towers. A historical review highlighted how these structures, together with the whole Cathedral, suffered intense damage and partial collapse during previous earthquakes. In order to identify the structure main deficiencies, both linear kinematic analyses and nonlinear static analyses have been performed. Different nonlinear finite element models have been created to evaluate the influence of the adjacent walls. Different load distributions have been compared to evaluate how simplified patterns could provide results close to load distributions taken from a modal analysis of the complex. A simple retrofit strategy, consisting on the introduction of steel ties, has also been studied as a reference. Results show good correlation between kinematic and pushover analyses. The construction, when compared to the requirements of the national code for new buildings, results significantly vulnerable, pointing out the need to accept some structural damage even after seismic retrofit.     

GENERATION OF ARTIFICIAL EARTHQUAKE MOTION RECORDS USING WAVELETS AND PRINCIPAL COMPONENT ANALYSIS

In the last century alone two to three million people died in earthquakes; More than 240 000 perish in Tangshan earthquake in China, 20 000 in the Izmit [Ikeya, 2004] 50 000 in India Bhuj earthquake, 100000 in Sumatra and 90000 in Pakistan earthquakes. Earthquake engineering has progressed to the stage where it is now computationally practical and desirable to perform a dynamic analysis of most civil engineering structures. Such an analysis requires the engineer to create an accurate analytical model of the structures as well as prescribe an earthquake input excitation. The design earthquake input excitation for the site under consideration is usually prescribed in the form of response spectra or in the form of an ensemble of artificial earthquake acceleration time histories. There is every need for generating artificial accelerograms since recorded accelerograms are very limited at site. This paper proposes five neural network based models for the generation of artificial earthquake and response spectra using wavelet transforms (WT) and principal component analysis (PCA) where the recorded accelerograms are limited at site of interest. The proposed model is compared with Lee and Han's model. The data for 25 earthquakes are taken for training and 4 for testing. Just like response spectra, this is also a convenient way of obtaining the design solution to a structural dynamics problem and is certainly an important tool.     

Numerical Evaluation of Seismic Soil Pressures on Rigid Walls Fixed to the Bedrock

Seismic soil pressures developed on a 7 m rigid retaining wall fixed to the bedrock are investigated using a finite element model that engages nonlinear soil intended materials available in OpenSees. This allows incorporation of the inelastic behavior of the soil and wave propagation effects in the soil-wall system seismic response. The nonlinear response of the soil was validated using the well-stablished, frequency-domain, linear-equivalent approach. An incremental dynamic analysis was implemented to comprehensively examine the effect of soil nonlinearity and input motion on the induced seismic pressures and to evaluate current code equations/methodologies at different levels of earthquake intensity. The results show that soil nonlinearity and seismic wave amplification may play an important role in the response of the soil-wall system. Therefore, methodologies that rely only on peak ground acceleration may introduce large bias on the estimated seismic pressures in scenarios where high nonlinearity and site amplification are expected.     

An Analytical Study on the Seismic Vulnerability of Masonry Buildings in India

Two analytical models for unreinforced masonry (URM) buildings are proposed with the aim to simulate their seismic response and to estimate corresponding vulnerability functions. The proposed models are implemented in SAP 2000 nonlinear software to obtain capacity curve parameters for representative Indian URM buildings, based on a field survey and statistical analysis. Vulnerability functions are estimated using the obtained capacity curves. Damage Probability Matrices (DPMs) are obtained using the approximate PGA-intensity correlation relationship as per Indian seismic building code and are compared with the commonly used intensity scales and empirical damage data observed after the 2001 Bhuj earthquake.     

Geneva's future: reflections on the role of a values‐based city

In a world where most of the great cities are heavily branding themselves to compete for lucrativebusiness, political and sporting events, what future role is there for an international values‐based city like Geneva? This article reflects on the history of ideas that have taken root in Geneva over the centuries and suggests how they might be actively re‐positioned to give the city continuing relevance in the coming century. It looks at eleven political and practical ideas that have hadimportant manifestations in Geneva and have been embodied in some of its international organizations, notably: freedom of movement; free thinking; political self‐determination; compassionate warfare; peace and trade among others. It then argues that, in order to survive as a leading international city, Geneva must develop real expertise on these big‐hitting political issues, improve its ability to deliver on them and create a dynamic alliance of other internationalist valuesbased cities around the world which can mobilize similar concerns and embody a similarly Genevan model of international space.     

A Checking Method for Multiple Seismic Performance Objectives of Bridge Piers Designed According to Code Provisions

Seismic bridge design codes require that bridge piers designed according to prescribed design rules should attain specified multiple seismic performance objectives. However, design codes do not explicitly require checking the attainment of specified performance objectives for designed bridge piers. In this article, seismic performance levels have been correlated with engineering damage parameters. A checking method for multiple seismic performance objectives of bridge piers has been outlined and validated with experimental results. The application of the method has been demonstrated by checking the performance of a bridge pier designed according to a code provision for a wide range earthquake ground motions.     

EVALUATION OF ACCIDENTAL ECCENTRICITY IN BUILDINGS DUE TO ROTATIONAL COMPONENT OF EARTHQUAKE

This study adopts a random procedure in the evaluation of the effect of the rotational component of earthquake on the accidental eccentricity of symmetric and asymmetric buildings. The spectral density function of the rotational component of earthquake acceleration (about the vertical axis) is obtained on the basis of the spectral density function of the horizontal component of earthquake acceleration. The rotational component of an earthquake can increase the response of the structure. The degree of the increase is highly dependent upon the dynamic characteristics of the system and the rotational component of the earthquake. To bring this increase under consideration, seismic codes represent a parameter referred to as accidental eccentricity, as a part of the design eccentricity. The purpose of the present study is to estimate the value of this increase and to make appropriate suggestions based on frequency domain analysis.     

SEISMIC HAZARD ASSESSMENT IN FLORENCE CITY ITALY

A seismic hazard analysis of Florence city was performed in the frame of a project concerning the dynamic behaviour of cable-stayed bridges. Both a probabilistic approach and a methodology based on the use of a local macroseismic catalogue were applied. A local catalogue was expressly compiled for this purpose, to collect the macroseismic intensities actually observed at the site as a result of past earthquakes. This sort of catalogue is an independent tool to verify the assumptions of the probabilistic approach (seismic zoning, earthquake recurrence relation, attenuation model), though it can supply results in terms of macroseismic intensity only and reflects the effective seismic history at the site, without taking into account any variability. The Cornell' methodology was used to assess probabilistic hazard in terms of macroseismic intensity, peak ground acceleration, peak ground velocity, and pseudovelocity uniform response spectra. The local catalogue points out level VII of the Mercalli-Cancani-Sieberg scale (MCS) as the maximum intensity historically observed in Florence. The probabilistic approach leads to the consideration of intensity VIII MCS as the maximum credible for the city. The probabilistic analysis in terms of ground motion was performed using attenuation relations estimated for alluvium sites, since the geology of Florence area is represented by fluvial and lacustrine deposits of various thickness. Peak ground acceleration values with 90% non exceedence probability in 50 and 500 years are respectively 145 and 219 cm/s's for a shallow alluvium site, and 95 and 157 cm/s's for a deep alluvium site; the corresponding peak ground velocity values for sites located on alluvium are 6.41 and 11.76 cm/s. Uniform response spectra are provided for shallow and deep alluvium sites, according to frequency-dependent attenuation relations estimated from strong Italian earthquakes.     

NON-LINEAR SEISMIC RESPONSE OF ECS DESIGNED RC BUILDING STRUCTURES

In this paper, results of an analytical study on the non-linear dynamic behaviour of reinforced concrete buildings designed according to modern European Codes (Eurocode 8) are presented. An investigation of the seismic performance of 8-storey regular and irregular buildings is carried out. The study is aimed at evaluating their seismic structural performance with a focus on the influence of several design parameters used in the code affecting non-linear response. Towards this aim, use is made of a suite of spectrum-compatible artificial accelerograms. It is concluded that EC8 provisions, although correct in principle, are conservative, at least for the structures and input motions considered, in view of the very low predicted damage levels observed in most cases.     

中国热点旅游城市旅游国际化水平定量评价研究

从国际旅游业发展水平和国际旅游业发展环境两大方面入手,构建了4层39个指标的评价体系,采用层次分析法,定量评价了中国27座热点旅游城市的旅游国际化水平。在此基础上,运用SPSS软件进行聚类分析,将中国热点旅游城市的旅游国际化水平划分为4种类型,最后分析了各城市旅游国际水平的优劣势和提升方向。     

文物防震措施研究初探

台北故宫博物院珍藏中国历代名瓷和玉器其数量和种类居全世界博物馆之冠,目前陈列柜内瓷器及玉器的防震措施仍有改善的空间,因此运用现代科学方法和仪器研究文物防震措施,更突显其重要性和迫切性。本研究使用的方法为传统文物防震措施(使用微晶蜡固定、铁弗龙、橡胶垫和防震塑料垫衬底)、柜内型隔震台减震和电磁铁固定陈列柜功能性测试;运用台湾地震工程研究中心的人工地震台执行上述不同方法之实验。实验结果,传统方法抗震优劣顺序为:微晶蜡>铁弗龙>塑料垫>橡胶垫;柜内型隔震台消能减震功效可达60％;至于电磁铁固定陈列柜防震在加速度超过800gal时,才显现摇摆现象,未装电磁铁的陈列柜,加速度超过300gal时,即有自震现象。然而在瓷器、玉器陈列柜内实务执行防震措施的层面,宜使用微晶蜡固定最为经济有效,柜内型隔震台亦可使用,但需考量柜内可滑动空间是否充裕的实际状况执行。