Seismic assessment of unanchored steel storage tanks by endurance time method

Liquid storage tanks are essential structures that are often located in residential and industrial areas; thus an assessment of their seismic performance is an important engineering issue. In this paper, the seismic response ofunanchored steel liquid storage tanks is investigated using the endurance time （ET） dynamic analysis procedure and compared to responses obtained for anchored tanks under actual ground motions and intensifying ET records. In most cases, the results from ground motions are properly obtained with negligible differences using ET records. It is observed that uplifting of the tank base, which is closely related to the tank aspect ratio, has the greatest significance in the responses of the tank and can be predicted with reasonable accuracy by using currently available ET records.

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.

Seismic safety assessment with non-Gaussian random processes for train-bridge coupled systems

Extensive high-speed railway(HSR)network resembled the intricate vascular system of the human body,crisscrossing mainlands.Seismic events,known for their unpredictability,pose a significant threat to both trains and bridges,given the HSR’s extended operational duration.Therefore,ensuring the running safety of train-bridge coupled(TBC)system,primarily composed of simply supported beam bridges,is paramount.Traditional methods like the Monte Carlo method fall short in analyzing this intricate system efficiently.Instead,efficient algorithm like the new point estimate method combined with moment expansion approximation(NPEM-MEA)is applied to study random responses of numerical simulation TBC systems.Validation of the NPEM-MEA’s feasibility is conducted using the Monte Carlo method.Comparative analysis confirms the accuracy and efficiency of the method,with a recommended truncation order of four to six for the NPEM-MEA.Additionally,the influences of seismic magnitude and epicentral distance are discussed based on the random dynamic responses in the TBC system.This methodology not only facilitates seismic safety assessments for TBC systems but also contributes to standard-setting for these systems under earthquake conditions.

Evolution of Coulomb failure stress in Sulaiman Lobe,Pakistan,and its implications for seismic hazard assessment

In this research work,we present the evolution of Coulomb failure stress(CFS)in the Sulaiman Lobe and its implications for seismic hazard assessment.The Chaman transform fault,~1,000 km long,is the major active fault that marks the western boundary between Pakistan and Afghanistan on the Indian Plate.To date,few studies have been conducted to unveil the interactions among earthquakes and the implications of these interactions for seismic hazard assessment in the region.We thoroughly investigated the published and online catalog to construct a sequence of major earthquakes that occurred in this region during the past.The final earthquake sequence was composed of 15 earthquakes of M_(w)≥6.0,beginning with the 1888 earthquake.We used the stress-triggering theory to numerically simulate the evolution of CFS caused by these earthquakes.The numerical results revealed that 8 out of 15earthquakes were triggered by the preceding earthquakes.The earthquakes in 1908,1910,1935,1966,and 1997 were rather independent earthquakes in this sequence.Although the epicenters of the 1975a and 1975b earthquakes were in the stress shadow zone,the partial rupture segments of both these earthquakes were in high-CFS regions.The CFS induced by the 1935 earthquake was notable,as it later triggered the 2008 doublet.Moreover,our results revealed that the northern segment of the Chaman Fault,the southern segment of the Ghazaband Fault,and the northwestern segment of the Urghargai Fault demonstrated a high change in CFS that could trigger seismicity in these regions.The necessary arrangements must therefore be made to mitigate any possible seismic hazards in the region.

Seismic loss assessment of RC high-rise buildings designed according to Eurocode 8

A probabilistic seismic loss assessment of RC high-rise(RCHR)buildings designed according to Eurocode 8 and located in the Southern Euro-Mediterranean zone is presented herein.The loss assessment methodology is based on a comprehensive simulation approach which takes into account ground motion(GM)uncertainty,and the random effects in seismic demand,as well as in predicting the damage states(DSs).The methodology is implemented on three RCHR buildings of 20-story,30-story and 40-story with a core wall structural system.The loss functions described by a cumulative lognormal probability distribution are obtained for two intensity levels for a large set of simulations(NLTHAs)based on 60 GM records with a wide range of magnitude(M),distance to source(R)and different site soil conditions(SS).The losses expressed in percent of building replacement cost for RCHR buildings are obtained.In the estimation of losses,both structural(S)and nonstructural(NS)damage for four DSs are considered.The effect of different GM characteristics(M,R and SS)on the obtained losses are investigated.Finally,the estimated performance of the RCHR buildings are checked to ensure that they fulfill limit state requirements according to Eurocode 8.

Three-dimensional pseudo-dynamic reliability analysis of seismic shield tunnel faces combined with sparse polynomial chaos expansion

To address the seismic face stability challenges encountered in urban and subsea tunnel construction,an efficient probabilistic analysis framework for shield tunnel faces under seismic conditions is proposed.Based on the upper-bound theory of limit analysis,an improved three-dimensional discrete deterministic mechanism,accounting for the heterogeneous nature of soil media,is formulated to evaluate seismic face stability.The metamodel of failure probabilistic assessments for seismic tunnel faces is constructed by integrating the sparse polynomial chaos expansion method(SPCE)with the modified pseudo-dynamic approach(MPD).The improved deterministic model is validated by comparing with published literature and numerical simulations results,and the SPCE-MPD metamodel is examined with the traditional MCS method.Based on the SPCE-MPD metamodels,the seismic effects on face failure probability and reliability index are presented and the global sensitivity analysis(GSA)is involved to reflect the influence order of seismic action parameters.Finally,the proposed approach is tested to be effective by a engineering case of the Chengdu outer ring tunnel.The results show that higher uncertainty of seismic response on face stability should be noticed in areas with intense earthquakes and variation of seismic wave velocity has the most profound influence on tunnel face stability.

Detailed seismic zoning of the East Kazakhstan region in the Republic of Kazakhstan

Kazakhstan is currently drafting new construction regulations that comply with the major provisions of the Eurocodes.Such regulations are created on the basis of seismic zoning maps of various degrees of detail,developed by our Institute of Seismology using a new methodological approach for Kazakhstan.The article is about creating the first normative map of the Detailed Seismic Zoning on a probabilistic foundation for the Republic of Kazakhstan’s East Kazakhstan region.We carried out the probabilistic assessment of seismic hazard using a methodology consistent with the main provisions of Eurocode 8and updated compared with that used in developing maps of Kazakhstan’s General Seismic Zoning and seismic microzoning of Almaty.The most thorough and current data accessible for the area under consideration were combined with contemporary analytical techniques.Updates have been done to not only the databases being used but also the way seismic sources were shown,including active faults now.On a scale of 1:1000000,precise seismic zoning maps of the East Kazakhstan region were created for two probabilities of exceedance:10%and 2%in 50 years in terms of peak ground accelerations and macroseismic intensities.The obtained seismic hazard distribution is generally consistent with the General Seismic Zoning of Kazakhstan’s previous findings.However,because active faults were included and a thoroughly revised catalog was used,there are more pronounced zones of increased danger along the fault in the western part of the region.In the west of the territory,acceleration values also increased due to a more accurate consideration of seismotectonic conditions.Zoning maps are the basis for developing new state building regulations of the Republic of Kazakhstan.

Simplified seismic performance assessment and implications for seismic design

The last decade or so has seen the development of refined performance-based earthquake engineering(PBEE) approaches that now provide a framework for estimation of a range of important decision variables,such as repair costs,repair time and number of casualties. This paper reviews current tools for PBEE,including the PACT software,and examines the possibility of extending the innovative displacement-based assessment approach as a simplified structural analysis option for performance assessment. Details of the displacement-based s+eismic assessment method are reviewed and a simple means of quickly assessing multiple hazard levels is proposed. Furthermore,proposals for a simple definition of collapse fragility and relations between equivalent single-degree-of-freedom characteristics and multi-degree-of-freedom story drift and floor acceleration demands are discussed,highlighting needs for future research. To illustrate the potential of the methodology,performance measures obtained from the simplified method are compared with those computed using the results of incremental dynamic analyses within the PEER performance-based earthquake engineering framework,applied to a benchmark building. The comparison illustrates that the simplified method could be a very effective conceptual seismic design tool. The advantages and disadvantages of the simplified approach are discussed and potential implications of advanced seismic performance assessments for conceptual seismic design are highlighted through examination of different case study scenarios including different structural configurations.

Assessment of Seismic Damage in Nativity Church in Bethlehem Using Pushover Analysis

This study focuses on advanced finite element(FE)analyses on The Church of Nativity located in Bethlehem(Palestine),one of the most historic structures in the world.To ensure the model quality,a 3D FE model was created using two types of typical commercial software,DIANA FEA and SAP2000.From analyses,one of the expected behaviors for this kind of masonry structure“low modal period”was found.The seismic behavior of the church was studied using pushover analyses,which were conducted using DIANA FEA.The first unidirectional mass proportional load pattern was created in both directions,X-direction as a longitudinal direction and Y-direction as the transversal direction.An incremental iterative procedure was used with monotonically increasing horizontal loads,using constant gravity loads.The results showed that the transversal direction is the most vulnerable and the damage concentrates at the main lateral(longitudinal)walls,mainly at the south and north alignment walls,and also at the vaults and at the connections of the vaults to the apse.Crack width was at the upper limit in the in-plane direction(X-direction).While,in Y-direction,it exceeded the limits of IBC code in width and length with a maximum width of 13.7 mm.A more accurate nonlinear dynamic analysis is recommended in the near future,which takes into account the material nonlinearity for more reasonable seismic behavior simulation.

Seismic Performance Assessment of Reinforced Concrete Box Culverts under Near and Far Fault Seismic Ground Motion Records

Studying the critical response characteristics of reinforced concrete box culverts with diverse geometrical configurations under seismic excitations is a necessary step to develop a reasonable design method. In this work, numerical analysis and assessment of reinforced concrete box culverts for seismic loading in addition to standard static loading from dead and live loads is conducted, aiming to highlight the critical difference in the seismic performances between two and three cell box culverts under near and far-fault ground motion. The results show how and where the seismic loading alters the responses of seismic loading of the models including the effect on safety and failure. The geometrical configurations of the culvert combined with the loading scenarios also significantly influence the magnitude and distribution of the seismic responses. The findings of this work shed light on the critical role of the geometrical configurations and shaking event in the seismic responses of reinforced concrete box culverts and this procedure can be applied as seismic assessment method to any culvert shape, size, and material.

Seismic hazard assessment of the Three Gorges Project

Seismic monitoring data for the past 50 years in the Three Gorges Reservoir area show that the reservoir head area is a typical weak seismic region with low seismieity before impoundment and that the epicenters were concentrated in the east and west sides of the Zigui Basin, most of which were natural tectonic earth- quakes. After impoundment, the seismic activity shifted to the segment between Badong and Zigui along the Yangtze River, mainly within 5 km of the reservoir bank. The seismogenesis was categorized into four types： Karst collapse earthquakes, earthquakes caused by Karst gas explosion, mining tunnel collapse earthquakes, and rock （terrane） slip earthquakes, all of which are related to the lithology, structure, and tectonics of near- surface geological bodies of the area. Compared with the seismicity before impoundment, the seismic frequency increase was remarkable, with most of the magnitudes below Ms2.0. Therefore, the intensity of the earth- quakes remained at a low level. On November 22, 2008, a magnitude 4.1 earthquake, the largest earthquake recorded since impoundment, occurred in Quyuan Town, Zigui County. The intensity and PGA of reservoir-in- duced earthquakes are higher than those of tectonic earthquakes with equal magnitude, but the peak intensity of reservoir-induced earthquakes is not likely to go beyond that of the estimated range from earlier studies.

Probabilistic seismic hazard assessment of Kazakhstan and Almaty city in peak ground accelerations

As for many post-soviet countries, Kazakhstan’s building code for seismic design was based on a deterministic approach. Recently, Kazakhstan seismologists are engaged to adapt the PSHA(probabilistic hazard assessment) procedure to the large amount of available geological, geophysical and tectonic Kazakh data and to meet standard requirements for the Eurocode 8. The new procedure has been used within National projects to develop the Probabilistic GSZ(General Seismic Zoning) maps of the Kazakhstan territory and the SMZ(Probabilistic Seismic Microzoning) maps of Almaty city. They agree with the seismic design principles of Eurocode 8 and are expressed in terms of not only seismic intensity,but also engineering parameters(peak ground acceleration PGA). The whole packet of maps has been developed by the Institute of Seismology, together with other Kazakhstan Institutions. Our group was responsible for making analysis in PGA. The GSZ maps and hazard assessment maps for SMZ in terms of PGA for return periods 475 and 2475 years are considered in the article.

Seismic Hazard Assessment of District Mansehra,Khyber Pakhtoonkhawa,Pakistan

The site of Mansehra is located seismically in an active regime, known as the Crystalline Nappe Zone and Hazara-Kashmir Syntaxis in NW Himalayas, Pakistan. Seismic Hazard Assessment （SHA） for the site has been carried out by considering the earthquake source zones, selection of appropriate attenuation equations, near fault effects and maximum potential magnitude estimation. The Mansehra Thrust, Oghi Fault, Banna Thrust, Balakot Shear Zone, Main Boundary Thrust, Panjal Thrust, Jhelum Fault and Muzaffarabad Fault and, further to the south, the Sanghargali, Nathiagali, and Thandiani Thrusts are the most critical tectonic features within the 50 km radius of Mansehra. Using the available instrumental seismological data from 1904 to 2007, SHA has been carried out. Other reactivated critical tectonic features in the area have been investigated. Among them the Balakot-Bagh fault, with the fault length of 120 km from Balakot to Poonch, has been considered as the most critical tectonic feature on the basis of geological/structural/seismological data. The potential earthquake of maximum magnitude 7.8 has been assigned to the Balakot-Bagh fault using four regression relations. The peak ground acceleration value of 0.25 g （10% probability of exceedance for 50 years） and 0.5 g has been calculated with the help of the attenuation equation using probabilistic and deterministic approaches.

Case study of seismic performance assessment of irregular RC buildings: hospital structure of Avezzano(L'Aquila, Italy)

Most published studies on inelastic earthquake response of non-symmetric buildings are based on simplified inelastic, highly idealized models, while general conclusions regarding the inelastic torsional response of multistory building are still lacking. This paper aims to provide a useful contribution in the study of the torsional response of real irregular buildings. To this aim, the manuscript reports the comprehensive study on the seismic vulnerability of an irregular RC building： the hospital building ofAvezzano （L＇Aquila Italy）. For this multi-story building, which is irregular in both plan and elevation, the application of nonlinear static evaluation procedures is by no means straightforward. The study proposes a nonlinear static procedure based on pushover analysis under the multimodal distribution of lateral loads and a capacity spectrum method. This pushover procedure accounts for mass distribution, higher modes contribution and mode-shapes correlation. Furthermore, due to its non-iterative feature, it avoids problems of non-convergence and multiple solutions of the conventional capacity spectrum method. Applied to a real case study, the procedure is used to investigate, in a 3D plan irregular building, the sensitivity of torsional inelastic response to lateral force distribution, higher modes contribution, accidental eccentricity and controlled point for monitoring the target displacement.

Seismic fragility assessment of low-rise stone masonry buildings

Many historic buildings in old urban centers in Eastern Canada are made of stone masonry reputed to be highly vulnerable to seismic loads.Seismic risk assessment of stone masonry buildings is therefore the first step in the risk mitigation process to provide adequate planning for retrofit and preservation of historical urban centers.This paper focuses on development of analytical displacement-based fragility curves reflecting the characteristics of existing stone masonry buildings in Eastern Canada.The old historic center of Quebec City has been selected as a typical study area.The standard fragility analysis combines the inelastic spectral displacement,a structure-dependent earthquake intensity measure,and the building damage state correlated to the induced building displacement.The proposed procedure consists of a three-step development process：（1） mechanics-based capacity model,（2） displacement-based damage model and（3） seismic demand model.The damage estimation for a uniform hazard scenario of 2% in 50 years probability of exceedance indicates that slight to moderate damage is the most probable damage experienced by these stone masonry buildings.Comparison is also made with fragility curves implicit in the seismic risk assessment tools Hazus and ELER.Hazus shows the highest probability of the occurrence of no to slight damage,whereas the highest probability of extensive and complete damage is predicted with ELER.This comparison shows the importance of the development of fragility curves specific to the generic construction characteristics in the study area and emphasizes the need for critical use of regional risk assessment tools and generated results.

Seismic Hazard Assessment in the Boundary Region of Indo-China:First Phase of Implementation of the Global Seismic Hazard Assessment Program (GSHAP) in Continental Asia

The primary goal of the demonstration project endorsed by the Scientific and Technical Committee for IDNDR in 1992 is to ensure that national agencies are able to assess seismic hazard in a regionally coordinated fashion by using advanced methods.China,as a Regional Center of Central Southern Asia,has contacted with countries of the region to realistically practice seismic hazard assessments of Continental Asia.A test area located in the collision boundary between the Indian and Eurasian plates was chosen to examine the seismic hazard assessment approach in the regional coordinates.The seismotectonics and three versions of seismic sources of the test area are described in this paper and under the Global Seismic Hazard Assessment Program(GSHAP),guidelines an earthquake catalogue of the test area was assembled.Because of the incompleteness of earthquake data in different countries,we adopt different time windows for different magnitude intervals in order to obtain the seismicity parameters of sources.By

Cursory seismic drift assessment for buildings in moderate seismicity regions

This paper outlines a methodology to assess the seismic drift of reinforced concrete buildings with limited structural and geotechnical information. Based on the latest and the most advanced research on predicting potential near-field and far field earthquakes affecting Hong Kong, the engineering response spectra for both rock and soil sites are derived. A new step-by-step procedure for displacement-based seismic hazard assessment of building structures is proposed to determine the maximum inter-storey drift demand for reinforced concrete buildings. The primary information required for this assessment is only the depth of the soft soil above bedrock and the height of the building. This procedure is further extended to assess the maximum chord rotation angle demand for the coupling beam of coupled shear wall or frame wall structures, which may be very critical when subjected to earthquake forces. An example is provided to illustrate calibration of the assessment procedure by using actual engineering structural models.

Comprehensive Studies of Seismic Forecast and Seismic Hazard Assessment in Armenia, Current State and Prospects

The study of geophysical processes in different layers of the Earth,seismic hazard assessment,earthquake prediction,etc.are topical fundamental and applied problems.The development of a modern adequate methodology for assessing seismic hazards,operational forecasting of earthquakes.

On unified analysis of uncertainty in seismic hazard assessment

In this paper, firstly the current analysis methods of uncertainties in seismic hazard assessment (SHA) are systematically reviewed, and the existing problems are pointed out. At the same time, it is proposed that the uncertainties can be divided into three kinds, namely, randomness, fuzziness and incompleteness of knowledge, and they can be treated in a unified way. Then, based on marked point process theory, a general equation for SHA is obtained, and a general equation for uncertainty analysis is also given on the basis of total probability theorem. Finally, the relationship between the proposed analysis method with those currently used both at home and abroad is discussed. The analysis shows that they are just the special case of the proposed method.

A Physics‑Based Seismic Risk Assessment of the Qujiang Fault:From Dynamic Rupture to Disaster Estimation

This study achieved the construction of earthquake disaster scenarios based on physics-based methods-from fault dynamic rupture to seismic wave propagation-and then population and economic loss estimations.The physics-based dynamic rupture and strong ground motion simulations can fully consider the three-dimensional complexity of physical parameters such as fault geometry,stress field,rock properties,and terrain.Quantitative analysis of multiple seismic disaster scenarios along the Qujiang Fault in western Yunnan Province in southwestern China based on different nucleation locations was achieved.The results indicate that the northwestern segment of the Qujiang Fault is expected to experience significantly higher levels of damage compared to the southeastern segment.Additionally,there are significant variations in human losses,even though the economic losses are similar across different scenarios.Dali Bai Autonomous Prefecture,Chuxiong Yi Autonomous Prefecture,Yuxi City,Honghe Hani and Yi Autonomous Prefecture,and Wenshan Zhuang and Miao Autonomous Prefecture were identified as at medium to high seismic risks,with Yuxi and Honghe being particularly vulnerable.Implementing targeted earthquake prevention measures in Yuxi and Honghe will significantly mitigate the potential risks posed by the Qujiang Fault.Notably,although the fault is within Yuxi,Honghe is likely to suffer the most severe damage.These findings emphasize the importance of considering rupture directivity and its influence on ground motion distribution when assessing seismic risk.