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Nowadays, the demand for using jack-up platforms to carry out a large percentage of deep-water oil and gas exploration is steadily increasing. The response of jack-up platforms to the severe dynamic loads that may be encountered during the structure life is not examined enough. Therefore, this study attempts to investigate the response of jack-up platforms performance under the effect of dynamic loads due to wave, wind, earthquake and tsunami forces using the finite element method for two models with the lowest and highest hull elevations. The jack-up platform is located in the Gulf of Mexico. Earthquake accelerations are applied to the model in high and moderate seismic levels. In addition, tsunami waves are applied to the platform in three different directions at 0°, 45° and 90°. This study utilised Airy's linear wave approach to assess the surface elevations and wave kinematics. The reference wind velocity is 10 knots at 10 m over the mean water level. Results indicate that the dynamic response of the structure is affected by the height of the platform and by the increase of the platform hull elevation. The combination of the El-Centro earthquake, dead and live loads provides the major impact on the platform at the lowest (70 m) and highest (85 m) hull elevations. The comparison of all result proves that the jack-up platform hull under high earthquake intensity and tsunami waves with 45° has experienced maximum deformation. Moreover, raising the deck will increase the response of the dynamic load and displacements but will negatively affect the platform.

To decrease the overall cost of the project, it is highly recommended dropping the cost in different manners. To make economic structure, structure without losing the stiffness standards and the cost cutting should be done at every construction stages. The dual systems in building structure consist of structural walls and moment resisting frames. The walls are made up of RCC, which is expensive material. The purpose of current study is to discover the effect of reducing shear wall area in multistorey building to decrease cost. The buildings are provided with shear walls to improve the lateral load resistance. Post parametric analysis results shows that, the reduction in shear wall area should be modified to a certain limit up to 20 % for cost cutting. But in this study, the opening areas of shear wall are increased above 20% to 36.75% and verify the results of post analysis. In this study 8 cases are analysed with 0%, 11%, 14.20%, 20%, 33.20%, 29.05%, 35%, & 36.75% opening in shear wall and analysis is perform by Response Analysis Method of dynamic analysis using Staad.pro V8i software in Zone III of multistorey building (G+18). The effects of opening in the wall are studied by considering the moments, shear, and torsion, and axial forces in the beams and columns. It is observed that after a certain percentage of shear opening in walls the building fails in the drift at a certain height. To resolve this problem the flared area of height 0.5 m at the height of failure is provided to counteract the effect of drift. It was observed that by the introduction of shear belt the drift reduces which made the structure stable. Finally in this study, the opening of shear wall area is increased up to 35% and concrete area is reduced 1170.20 m2 , which is 534.2m2 more than the previous studies. Keywords: Shear Wall, Opening Area, Multi-storeyed Building, Seismic effects, Response Spectrum Method

We show that long-recognized seismicity in the central Virginia seismic zone of the eastern North American intraplate setting arises primarily from tectonic processes predicted by new, full...

Infrastructure refers to an aggregation of numerous facilities that constitute the backbone of urban operations. The lifeline systems are usually interdependent; thus, any damage to one system can cause a chain reaction, triggering failures in related and connected systems, leading to a cascade of disasters. Taiwan is located in the Circum-Pacific seismic zone, where earthquakes occur frequently. Moderate-to-large earthquakes can adversely affect the lifeline systems, severely impairing most urban functions. Therefore, understanding the effects of earthquakes of this intensity on lifeline systems as well as how these effects contribute to disaster scenarios in urban areas is a critical requirement for the Taiwanese government. From the disaster management perspective, this study constructed a seismic impact chain module for lifeline systems on the basis of an analysis of the direct and indirect impacts of seismic activity. Furthermore, the factor of infrastructure impact was examined using the matrix method. Simulations of 6.6 magnitude earthquakes along the Shanchiao fault were used to assess the impact chain of the lifeline system and the effectiveness of a hospital disaster rescue service. In the simulation, the lifeline systems in the epicentral area were directly damaged, whereas critical infrastructure was indirectly affected. Therefore, the study results will assist the authorities in making intelligent decisions regarding lifeline infrastructure and resource management.

Coastal cities in Beibu Gulf of China are creating new lands by reclaiming from coasts, and are located in a seismic zone. The reclaimed land consists of a thick layer of marine soft soil overlain ...

Following the 2011 moment magnitude, M 5.7 Mineral, Virginia, earthquake, we conducted a search for paleoliquefaction features and found 41 sand dikes, sand sills, and soft-sediment deformation features at 24 sites exposed in cutbanks along several rivers: (1) the South Anna River, where paleoliquefaction features were found in the epicentral area of the Mineral earthquake and farther downstream to the southeast; (2) the Mattaponi and Pamunkey Rivers east of the Fall Line, where liquefiable sediments are more common than in the epicentral area; and (3) the James River and Rivanna River–Stigger Creek, where a few sand dikes were found in the 1990s. Liquefaction features are grouped into two age categories based on dating of host sediment in which they occur and weathering characteristics of the features. A younger generation of features that formed during the past 350 yr are small, few in number, and appear to be limited to the James and Pamunkey Rivers. Though there are large uncertainties in their locations and magnitudes, one or more preinstrumental earthquakes, including the 1758, 1774, and 1875 events, likely caused these features. An older generation of liquefaction features that formed between 350 and 2800 yr ago are larger, more numerous, and more broadly distributed than the younger generation of features. Several earthquakes could account for the regional distribution of paleoliquefaction features, including one event of M 6.25–6.5 near Holly Grove, or two events of M 6.0 near Mineral and M 6.25 near Ashland. Amplification of ground motions in Coastal Plain sediment might have contributed to liquefaction along the Mattaponi and Pamunkey Rivers.

SUMMARY Interfaces are important part of Earth’s layering structure. Here, we developed a new model parametrization and iterative linearized inversion method that determines 1-D crustal velocity structure using surface wave dispersion, teleseismic P-wave receiver functions and Ps and PmP traveltimes. Unlike previous joint inversion methods, the new model parametrization includes interface depths and layer Vp/Vs ratios so that smoothness constraint can be conveniently applied to velocities of individual layers without affecting the velocity discontinuity across the interfaces. It also allows adding interface-related observation such as traveltimes of Ps and PmP in the joint inversion to eliminate the trade-off between interface depth and Vp/Vs ratio and therefore to reduce the uncertainties of results. Numerical tests show that the method is computationally efficient and the inversion results are robust and independent of the initial model. Application of the method to a dense linear array across the Wabash Valley Seismic Zone (WVSZ) produced a high-resolution crustal image in this seismically active region. The results show a 51–55-km-thick crust with a mid-crustal interface at 14–17 km. The crustal Vp/Vs ratio varies from 1.69 to 1.90. There are three pillow-like, ∼100 km apart high-velocity bodies sitting at the base of the crust and directly above each of them are a low-velocity anomaly in the middle crust and a high-velocity anomaly in the upper crust. They are interpreted to be produced by mantle magmatic intrusions and remelting during rifting events in the end of the Precambrian. The current diffuse seismicity in the WVSZ might be rooted in this ancient distributed rifting structure.

The Wabash Valley seismic zone (WVSZ) is a region of diffuse, modern intraplate seismicity in the central United States with a history of strong, late Quaternary and Holocene seismicity as determined through paleoliquefaction studies. Yet, there are no specific faults linked to these strong WVSZ paleoearthquakes, some of which were as large as Mw 7.2–7.5. A multidisciplinary investigation of a linear, 5-kilometer-long and ∼3-meter-high scarp on the Ohio River floodplain in the southernmost WVSZ in western Kentucky evaluated whether the scarp is a fluvial landform or a tectonic feature. Geomorphic mapping and optically stimulated luminescence geochronology show that the age and orientation of the scarp are inconsistent with surrounding fluvial landforms. Trenching, core drilling, seismic reflection, electrical resistivity profiling, and cross sections of petroleum well logs all indicate a blind fault directly underlies the scarp. The scarp is interpreted to be the fold axis of a down-to-the-west monocline formed in alluvium by slip on the underlying blind fault, herein named the Uniontown fault. The Uniontown fault connects the Hovey Lake fault, striking N20°E and having ∼0.5 km of documented strike-slip offset, with an unnamed fault complex to the south that strikes N40°E, suggesting the Uniontown fault is part of a larger, Paleozoic structure that has been reactivated with strike-slip deformation. Geomorphic mapping utilizing luminescence and radiocarbon geochronology indicates that folding and faulting occurred ∼3.5 ka. Paleoliquefaction was suppressed by a thick clay cap in the main Ohio Valley, but paleoliquefaction features are widespread on Ohio River tributaries. Gravel dikes at one site had a maximum age of 3.4±0.4 ka, confirming the region has experienced strong, late Holocene shaking. Estimates using vertical displacement and rupture length indicate that slip on the Uniontown scarp could produce an Mw 6.2–7.7 earthquake, which is comparable to other large paleoearthquakes in the WVSZ paleoseismic record.

The correlation between solar flares and coronal mass ejections generating solar wind plasma flows towards the Earth and the dynamics in time and power of earthquakes in the area of the Yellowstone supervolcano, that was not previously studied, is considered in four examples. The method of graphical correlation between the values of solar wind parameters, which bursts are directly related to the activation of solar processes, and subsequent increases in the values of earthquake magnitudes and their repeatability was used as a research tool. The author assumes that an additional energy input occurs to shallow earthquake foci and increases their power due to the action of breakthrough injections of plasma clumps into the Earth’s near-surface area detached into the magnetosphere geo-effective solar wind components. The problem under discussion is considered to be acute in connection with the work carried out here to predict a volcanic eruption. In the general scientific plan, it is proposed to include earthquakes study in programs of education as one of points for registration the influence of factors of solar-wind origin.

Earthquakes are one of the deadliest natural disasters. Our study focuses on detecting temporal patterns of earthquakes occurring along intraplate faults in the New Madrid seismic zone (NMSZ) within the middle of the United States from 1996–2016. Based on the magnitude and location of each earthquake, we developed a Bayesian clustering method to group hypocentres such that each group shared the same temporal pattern of occurrence. We constructed a matrix-variate Dirichlet process prior to describe temporal trends in the space and to detect regions showing similar temporal patterns. Simulations were conducted to assess accuracy and performance of the proposed method and to compare to other commonly used clustering methods such as Kmean, Kmedian and partition-around-medoids. We applied the method to NMSZ data to identify clusters of temporal patterns, which represent areas of stress that are potentially migrating over time. This information can then be used to assist in the prediction of future earthquakes.

The present paper presents different approaches which includes plasticity based criteria that helps in distinguish between liquefiable and non-liquefiable soils deposits having fine content. A brief review of the previous work has been mentioned to emphasise on the need of new parameters for liquefaction susceptibility of clayey soils. Clay content, liquid limit and water content are considered as key parameters that helps in liquefaction assessment. Several recommendations proposed by prominent researchers are described here to present wide range of plasticity index, liquid limit and other parameters that affects liquefaction behaviour of clayey soil significantly. But the differences in the range of plasticity index leads to confusion and misperception in determination of liquefaction susceptibility of fine grained soil. One of the high seismic zone site is analyzed using different approach which consider fine content of soil mass. It is found that for a better and proper segregation of the layers Bray and Sancio criteria may be adopted which uses plasticity as one of its input parameter and clearly differentiate site in between liquefiable, non-liquefiable and sites that may liquefy i.e. moderately liquefiable. This summarizes that plasticity is one of the significant criteria which draws a clear differentiating line between liquefiable and non-liquefiable soil deposits.

The geodynamic features of the north–south seismic zone (NSSZ) and the formation of the Emeishan large igneous province (ELIP) in China remain controversial. In this study, we conducted detailed P-wave teleseismic tomography studies in the NSSZ and adjacent regions. The results revealed large high-velocity anomalies beneath the Songpan–Ganzi Block and the South China Block, possibly representing large-scale lithospheric delamination. We further identified low-velocity structures at 50–200 km depths in the western and southern parts of the NSSZ, suggesting an upwelling asthenosphere induced by delamination and the absence of a rigid lithosphere. Two high-velocity structures beneath the Sichuan basin and the Alashan block were also revealed, which may represent the lithospheric roots of these structures. These rigid lithospheric roots may have obstructed the eastward extrusion of the Tibetan plateau and led to stress accumulation and release (triggering earthquakes) in the Longmenshan Orogenic Belt and the northern part of the NSSZ. Because of this obstruction, the eastward extrusion was redirected southeastward to Yunnan in the southern part of the NSSZ, which led to stress accumulation and release causing earthquakes along the Honghe and Xiaojiang faults. The results from this study reveal a high-velocity structure with a subducted slab-like appearance that may represent vestiges of the Paleo-Tethys oceanic lithosphere, which subducted beneath the ELIP and initiating large-scale mantle return flow or mantle upwelling, contributing to the formation of the ELIP.

This paper investigated multi-objective seismic damage assessment procedure. Primarily, it estimates damage index (DI) of reinforced concrete-framed residential buildings situated in seismic zone V as per IS-1893-2016 (0.36 g) in India. Three-dimensional DI has been estimated for a four-storey building by Park–Ang method. With the increase in the storey number, calculation of Park–Ang DI becomes tedious and more time-consuming procedure; therefore, this method is not suitable for large-scale damage investigation. To avoid the complexity, a simplified method has been proposed to estimate global damage index (GDI) of buildings easily. For this purpose, a four-storey residential building having plan aspect ratio 0.5, 0.75 and 1 has been analysed. In this study, the most influential parameters such as inter-storey drift, joint rotation and peak roof displacement have been combined to estimate GDI of structures directly. Based on this study, it has been observed that 0.893 times ground-storey DI (i.e. local DI) estimates similar Park–Ang GDI for a four-storey building. In this study, it has been observed that ground floor experiences maximum damage and top floor experiences least damage for all cases. The proposed approach effectively estimates reliable GDI that is useful for small- to large-scale damage assessment of buildings.

The Eurasian seismic belt is the second largest seismic zone in the world. It has numerous seismic activities which have enormous impact on human’s life. It is of importance to study the spatio–temporal characteristics of the Eurasian seismic belt. As we can learn from previous studies, fractal and fractal dimension theories can be used to study seismic activities. In general, the temporal sequence and the spatio sequence of earthquakes both exhibit the fractal structures. When huge earthquakes occur, the fractal dimension of the temporal sequence is very low. As the days went by, the value of fractal dimension fluctuates. The seismic data from 1973 to 2014 in The Eurasian seismic belt are selected as the object of this study. Based on the single fractal model, the complex structure of the seismic spatio and temporal distribution in the seismic belt is quantitatively evaluated. Results show that over time the time interval of the seismic activity shortened, and the seismic activity on the Eurasian seismic belt has a nonlinear structure and self-similar characteristics. From the perspective of space, the fractal dimension of the Eurasian seismic belt tends to grow with time, and it also has a nonlinear structure and self-similar characteristics. When the temporal unit is set as 1 year, the accumulation and release of energy are probably periodic: the minor period might be about 8.5 years, and the major period might be about 13 years.

This paper deals with the structural behaviour and the damage assessment of Italian “modern” masonry buildings during seismic events. “Modern” masonry buildings are characterized by a box-like structural behaviour, due to the presence of effective connections between horizontal floors and vertical load-bearing walls, which prevents local mechanisms such as the overturning of external facades during earthquakes. “Modern” masonry buildings were built in Italy since the first decades of XX century in those regions classified as seismic zone and since 1937 in the whole country, following the Italian code prescriptions that implicitly interdicted the erection of “ancient” masonry buildings. Starting from an in deep historical analysis of the Italian seismic codes’ prescriptions for the design of “modern” masonry buildings, the typical characteristics of the most frequent structural typologies of unreinforced masonry buildings are outlined. Then, the typical damage mechanisms observed in “modern” masonry buildings damaged after the L’Aquila earthquake (2009) are reported in relation with both the global and local behaviour of the whole building and its structural elements. The analysis demonstrated that “modern” masonry buildings experienced a good box-like seismic performance, which avoided global or local collapses, but shown severe damage to piers and spandrels related to their reduced in-plane shear capacity. Given the lack of data on such kind of structural typology, this study is fundamental for understanding and modelling the seismic behaviour of “modern” masonry buildings designed before ‘80s according to different seismic design prescriptions and for defining effective strengthening solutions for reducing their seismic vulnerability.

To reduce the overall cost of the project, it is highly recommend reducing the cost in different manner. To make economic structure, the cost cutting should be done in every construction stages. The dual systems in building structure consist of structural walls and moment resisting frames. The walls are made up of RCC, which is a costly material used. The purpose of current study is to explore the reduction in shear wall area in multistorey building to reduce cost. Total 5 buildings framed in Staad pro software abbreviated as SA, SB, SC, SD, SE supposed to be situated at Seismic Zone III. Post parametric analysis results shows that, the reduction in shear wall area should be adapted to a certain limit up to 20 % for cost cutting.

With the advancement in technology, urban transportation systems have been modernized with the construction of underground structures due to restricted movements and inadequate space. Many cities already have or plan to construct underground box structures for metros and subways. These structures may undergo severe damages caused by excessive deformation due to seismic shaking. Hence, it is necessary to have an accurate estimation of deformation and bending moment caused by the movement of the surrounding soil under seismic conditions. In the present investigation, an attempt has been made to carry out a parametric study for a typical box structure 9.6 m wide × 5.8 m high with varying soil parameters from loose to medium, medium to dense and very dense in different seismic zones. The results of the study reveal that about 16–26% of the variation in distortion and 8–12% of the variation in bending moment occur with different subsoil conditions (loose to medium, medium to dense and very dense) under the same seismic conditions. Once seismic conditions change from lower to higher seismic zone (zone-III to zone-IV), the deformation becomes almost double even for the same soil condition (loose to medium or medium to dense or very dense). The findings of the present study may be useful in the design of underground subways and metro box structures for practicing engineers.

The north-south seismic zone (NSSZ) is a destructive zone of large-scale earthquakes in China, and the earthquake mechanism associated with deep structures remains unclear. Previous studies have indicated that lithospheric delamination or absence of lithospheres in the western part of the NSSZ may facilitate the eastern extrusion of the Tibetan Plateau and lead to stress accumulation and release. However, the deep process of lithospheric delamination needs to be further clarified. In this study, I collect abundant high-quality teleseismic data recorded by permanent seismic stations and perform common conversion point (CCP) stacking of receiver functions in the north part of the NSSZ. The results show that lithospheric delamination might result in the splitting 660 km discontinuity and a thickening region of the mantle transition zone (MTZ).

Reinforced Concrete (RC) shear wall buildings are the most common construction practice in moderate to high seismic zones. Shear walls provide high strength, stiffness to the building system. However, the performance of RC shear wall buildings depends on various parameters like the location of shear walls, the aspect ratio of the shear wall, and the structural wall plan density. The revised Indian standards for earthquake-resistant design of structures states that RC structural wall plan density shall be at least 2% for buildings with open storeys, and for regular buildings it can be at least 2% along each principal direction. This manuscript aims to check the efficacy of the minimum structural plan density recommended in the revised Indian standard by evaluating the impact of varying structural wall density on the seismic performance of high-rise regular RC shear wall buildings located in the high seismic zone. The seismic performance of shear wall buildings with varying structural wall density is evaluated in terms of peak displacements, peak accelerations, and maximum inter-story drift by performing the time history analysis with different ground motion records. The effect of structural wall plan density on the dynamic properties of the buildings is also studied.

This paper discusses the risk assessment of earthquake on historical structures and monuments as per their height and shape with reference to the earthquake that occurred on 25 April 2015 and on 12 May 2015. Heritage Site, Dharahara tower, which was very high-rise in height, totally collapsed. Owing to such height the upper portions of 9-storied Basantapur Durbar, the Dasa Avtar temple were demolished by the quake. In an earlier earthquake in India near Aravali hill range in 1505, damaged Qutub Minar, Delhi built in 12th century, was fallen off its top two story, after like some quake due to sky/cloud bursting electric happening, but no such damage to ground, first and second story structures was noticed. Generally many old forts in India, were safe during earthquakes due to large in plan area and low in height , but further the high-rise old buildings suffered during earthquake at some specific intensity of earthquake at several times in past . It is important to point out the height and shape of historical structures and monuments for further safety measures and precautions as for as possible for load bearing structures, in Zone V with less than 400 sqm (appox.) in plan area of foundation with plinth may be risk affected during/after earthquake.

The effect of wind and earthquake on the structures can be specified briefly by the effect of horizontal forces act on structures varied in its value and direction depending on the location and the distance from the sea in case of wind load and the seismic activity of the region in case of an earthquake. These horizontal forces conflict in concept with the structural stability of the structure. Most of the designer engineers adopted the vertical forces only in design calculations and neglecting the horizontal forces based on the opinion that the horizontal forces are not effective. This design concept is wrong, thus it is necessary to take into consideration the effect of these horizontal forces on structures, especially there are a number of earthquakes took placed in different places of Iraq. So, it is necessary for dealing seriously with design calculations according to local and international common codes. This investigation presents a review for the design procedures of different codes, solved design examples according to different local and international codes, the difference in design between the horizontal and vertical forces and the methods to minimize the effect of wind and earthquake on structures. Data of 12 floors symmetrical building were adopted in seismic and wind analysis. The results of SAP2000 were compared with international common codes such as European, American, Brazilian, Italian and Romanian codes. The results of calculations revealed that there are some variations in the analysis of different codes. Romanian code is more conservative in calculating the lateral displacement and forces, while Italian code was low conservative.

Reinforced Concrete frame buildings lead the sector of building constructions in urban India. During the lifespan of a building, it experiences different types of static and dynamic forces. Static forces, being time independent in nature, primarily consist of the self-weight of the building. On the other hand, dynamic forces, which include earthquake force, are time dependent in nature. Seismic analysis of RC buildings can be carried out by both static as well as dynamic methods. Static method works on the assumption that the rate of application of the load is too slow to induce significant inertia forces in the structure, while in dynamic method, the inertia forces are taken under consideration. For low to medium rise buildings, static methods only can serve the purpose but for high rise buildings, dynamic analysis becomes crucial as they are affected worst by the earthquake forces. In the modern time, with growing demand and shrinking availability of land, buildings are getting taller and narrower. Hence, dynamic analysis has become necessary in a country like India, which had been shaken badly many times in the past by severe earthquakes causing substantial damage to structures and human life. Equivalent Static Method and Response Spectrum Method, which fall under the category of static and dynamic method respectively, are two of the most widely used methods for seismic analysis. According to Indian Standard codes, Equivalent Static Method is applicable for regular buildings with height less than 15 m in Seismic Zone II and Linear Dynamic Method is applicable for all other buildings. However, in design practice, it is observed that the Equivalent Static Method is also used for buildings of height more than 15 m in various seismic zones. In this paper, multi-storey framed structures of different heights situated in different seismic zones are analysed by Equivalent Static Method and Response Spectrum Method using a structural analysis software and a comparative analysis is performed between the results obtained from both the methods for responses such as bending moments, axial forces, and nodal displacements. Based on the comparisons the more suitable and accurate of the two methods of analysis for RC building is determined.

Tall building development has been rapidly increasing worldwide introducing new challenges that need to be met through engineering judgment. High rise buildings are very vulnerable to earthquake and wind loads on regular basis. Hence, to make high rise buildings safe against lateral loads, different types of structural systems are used. One of these structural systems is outrigger system. This project aims to show the analysis of a 60 storied three-dimensional building located at Delhi using ETABS 2016 software. Analysis of eight different models with outriggers and belt truss configuration is carried out by response spectrum method for seismic zone IV, to understand the performance for various parameters like maximum storey displacement, maximum storey drift and storey shear. The present work contains a comparative study on regular building with wall outriggers and braced outriggers. The results showed the reduction in responses by using outrigger and belt truss system.

Multi storey buildings are constructed by Reinforced concrete are subjected to earthquake forces are affected dangerously, they get failure during earthquake. The main reason for this failure is that the irregularity in building structures. In this paper study is made to find the response of regular and irregular building structures having plan irregularity located in seismic zone V. In this present study Analysis has been made by taking 10 storey building by Response Spectrum Method using ETABS 2015 and code IS 1893:2002 (part 1). Analysis is carried out for Regular and Irregular buildings at a height of 35.5 m in zone V. Behavior of structures are comparing the responses in the form of maximum storey displacement, storey drift, storey stiffness, periods and frequencies of modes during earthquake. Presently there are four models. One is Regular structure and remaining are Irregular structural models, all models have different shape but having same area. An attempt is made to study the Response of building structures with respect to the loads and their combinations. The results comparison is made by taking maximum load combinations considering the primary loads (LL, DL, WL, and EQL). Totally four Configuration models are considered for the analysis.

Liquefaction is associated with the loss of shear strength of soil, causing considerable damages. The Northeast Indian region has experienced many major (M ≥ 7.0) to great earthquakes (EQs) such as 1869 Cachar EQ and 1897 Shillong EQ. As a consequence, Guwahati city had faced large scale damage and significant induced effects such as liquefaction during past EQs. At present, Guwahati is the largest business hub of the northeast India. Further, Guwahati is also amongst the list of cities, Government of India has shortlisted to be developed as “smart city”. For these reasons, the city attracts lots of infrastructural growth in the times to come. In the present work, the liquefaction potential of Guwahati subsoil is evaluated. For the purpose, seismic scenarios experiences during 1869 Cachar EQ (Mw = 7.5), 1897 Shillong EQ (Mw = 8.1), average horizontal seismic coefficient given by IS 1893 (Part 1): 2016 (seismic zone V) and maximum amplified peak ground acceleration (PGA) values obtained based on site-specific subsoil data are considered separately. In-situ subsoil properties are obtained from 244 boreholes (BHs) till 30 m depth and maps showing possible liquefiable zones across Guwahati are developed. In addition, maps showing target SPT-N value ($$N^{improved}$$), to be obtained at above liquefiable zones after ground improvement, ensuring no further liquefaction, are also developed. Thus, the present study collectively identify zones which may undergo liquefaction during future EQs and further, how much improvement in the subsoil strength properties are required so that the above found liquefaction can be avoided, is also estimated. Obtained results and proposed values will provide very useful information to field engineers regarding where and how much ground improvement is required for avoiding future liquefaction. In addition, the present study is very helpful for city planning and microzonation studies.

In this publication we consider how local seismicity in the Racha-Dzhava seismic zone of the Caucasus changed in time under the influence of large earthquakes that occurred in 1971–2011. In order to divide the whole studied period into time intervals within which the total energy released by local earthquakes was summed up, we use the averaged focal mechanisms (obtained from the first P-waves arrivals) of earthquakes presented in the Seismological Bulletins of the Caucasus. The averaged focal mechanisms were built according to the method of K. Aki, in the terms of which a set of weak local earthquakes with a close distribution of the first P-waves arrivals are considered one large earthquake. The change in averaged focal mechanisms with time is revealed; this is associated with a change in tectonic stresses within the Racha-Dzhava zone. We also compare the changes in directions of tectonic stresses and the influence of strong earthquakes. It is shown that one of the factors of an abrupt and short-term change in a stress state and in a local seismicity level is an impact of distant strong and catastrophic earthquakes. The results can be interesting for understanding some aspects of local seismic activity and the causes of changes in the stress field and the activity of seismic process in the Racha-Dzhava seismic zone.

According to the results of continuous long-term seismic-ecological monitoring at the Caucasian Mineral Waters test plot (the seismic zone in the Cis-Elbrus region), data on the seismic velocity distribution pattern were obtained for the test plot territory. The high-speed structure is revealed, the horizontal dimensions of which do not allow predicting local earthquakes with a very high magnitude in this territory. Three-dimensional models of anisotropy index γ were obtained and the indexes of stress state S were estimated for different depths according to the interpretation results of converted PS waves from distant earthquakes. It is found that the distribution of the anisotropy index γ varies continuously by the depth, by the laterals and in time. The cyclic changes in the index S with time are noted for all depths.

One of the prevalent seismic damage modes of skewed bridges is that the shear keys and/or other transverse retainers at the acute corners suffer severer damages than those at the obtuse corners. In practice, the retainers are usually designed and detailed as structural fuses to protect the substructure and foundation in high seismic zones. However, in low seismic zone, such as seismic zone 1 in AASHTO, they are designed elastic. In this paper, a parameter study was conducted to: (1) investigate the distribution of forces among the shear keys in skewed bridges and (2) evaluate AASHTO’s provisions for the minimum connection force of shear keys in low seismic zone. Parameters of interest include skew angle and expansion gap size. An experimentally validated numerical model was employed to model the prototype bridges with exterior shear keys. Nonlinear response history analysis was performed. The results show that when the longitudinal gap is closed for small to moderate gaps, the forces in the keys at the acute corners can be much higher than those at the obtuse corners. This is most likely to occur since the keys should resist the transverse loading along with the impact and friction forces at the abutment-deck interface caused by longitudinal motion. These higher forces of the keys at the acute corners could exceed AASHTO’s limit in low seismic zone. To reduce the forces in the keys, it is recommended that the gap be increased in size to avoid abutment pounding, which is an affordable solution in low seismic zone since the increase is expected to be small. Further, a Simplified Method is developed to estimate the maximum connection forces of skew bridges in low seismic zone. Good agreement was obtained between the Simplified Method and the FEM model. Therefore, the Simplified Method may be used for the preliminary design of shear keys.

Purpose It is well known that the real behaviour of joints lies between the ideal pinned or rigid joint responses. Additionally the influence of this behaviour on the global structural response has been widely studied in the past centred on the plastic resistance or the critical load. On the other hand, there are relatively few studies focusing on the dynamical response of these structures. This paper aims to discuss these issues. Design/methodology/approach Two types of structures with rigid and semi-rigid joints were considered. Their inelastic response was evaluated using the N2 conventional pushover method, and were later compared to the results from a full non-linear dynamic analysis. Findings The results indicated that increasing joint flexibility makes the structure less rigid, lengthening its fundamental period and enhancing its horizontal displacement. Furthermore, a parametric study showed that joint flexibility might be of paramount importance to low to medium rise buildings response. Originality/value The evaluation of the influence of joint flexibility on the inelastic behaviour of steel structures located in seismic zone is of paramount importance, and is tackled in this paper.

We perform a comparative spatial analysis of inter-seismic earthquake production of rupture area and volume in southern California using observed seismicity and basic scaling relations from earthquake phenomenology and fracture mechanics. The analysis employs background events from a declustered catalog in the magnitude range 2 ≤ M 4 to get temporally stable results representing activity during a typical inter-seismic period on all faults. Regions of high relative inter-seismic damage production include the San Jacinto fault, South Central Transverse Ranges especially near major fault junctions (Cajon Pass and San Gorgonio Pass), Eastern CA Shear Zone (ECSZ) and the Imperial Valley – Brawley seismic zone area. These regions are correlated with low velocity zones in detailed tomography studies. A quasi-linear zone with ongoing damage production extends between the Imperial fault and ECSZ and may indicate a possible future location of the main plate boundary in the area. The regions around the 1992 M6.1 Joshua Tree, M7.3 Landers and M6.3 Big Bear earthquakes have background seismic activity before 1990. This may represent a regional weakening process by damage production in future rupture zones. The depth of background seismicity and damage production decreases steadily from SW of the coastline to NE of the San Andreas fault, and also to the SE near the US–Mexico border. The seismicity and rock damage become more pronounced and continuous along-strike of main faults with increasing depth.

In this paper we investigate the dynamic behavior of a system of interconnected faults in the Brawley Seismic Zone (BSZ) in southern California. The system of faults includes the southern San Andreas Fault (SSAF), the Imperial Fault (IF), and a set of cross faults in the BSZ that may serve as connecting structures between the two larger faults. Geological and seismic evidence imply that the SSAF and IF may have buried extensions that link them together in a large‐scale step over, with the cross faults in the BSZ cutting between them. Such a configuration poses the question of whether through‐going rupture across the step over is possible in this region, leading to large, plate‐boundary scale earthquakes. We investigate potential earthquakes in this region through 3‐D dynamic finite element spontaneous rupture modeling. We find that under multiple assumptions about fault stress and fault geometry, through‐going rupture is possible, both from north to south and south to north. Participation of the cross faults is facilitated by two factors: absence of rupture on one of the main two faults and a contrast in prestress between the main faults and the cross faults, leading to slow propagation speed on the main faults while maintaining ease of failure on the cross faults. The pattern of rupture propagation and slip is strongly affected by fault‐to‐fault dynamic stress interactions during the rupture process. The results may have implications for both potential earthquakes in this region, as well as for understanding the dynamics of geometrically complex/branched faults in general. Published version

Wilayah Indonesia mencakup daerah-daerah yang mempunyai tingkat resiko gempa yang tinggidiantara beberapa daerah gempa diseluruh dunia. Hampir setiap tahun terjadi bencana akibat gempabumi di berbagai tempat di Indonesia. Gempa yang terjadi dapat mengakibatkan kerusakan yangmenimbulkan korban jiwa serta dampaknya besar terhadap ekonomi dan pembangunan daerah diwilayah tersebut. Tujuan penelitian ini adalah melakukan perencanaan struktur gedung baja tahangempa berdasarkan peraturan SNI 02-1726-2002 dan FEMA 450, dan pembahasan meliputi penentuanukuran profil baja yang digunakan sebagai elemen struktur balok dan kolom, gaya geser dasar,peralihan, desain sambungan, dan perhitungan pondasi. Hasil desain balok dan kolom denganmenggunakan beban gempa berdasarkan SNI 02-1726-2002 dan FEMA 450 memberikan hasil yangsama untuk nilai rasio P/M. Nilai gaya geser nominal arah-x (Vx) mempunyai perbedaan sebesar0,08%, sedangkan nilai gaya geser nominal arah-y (Vy) mempunyai perbedaan sebesar 0,16%. Hal initerjadi karena hasil perhitungan nilai Fxi dan Fyi dengan kedua metode tersebut memberikan hasil yanghampir sama. Perbedaan nilai Vu pada balok sebesar 0,09%, dan Mu mempunyai selisih sebesar0,00%. Nilai Vu dan Mu pada kolom mempunyai hasil yang sama, perbedaan nilai Nu sebesar 0,18%.Pada reaksi tumpuan, memberikan hasil yang hampir sama, sehingga menghasilkan pondasi danpilecap yang sama. Pada desain sambungan, baut dan pelat mempunyai hasil yang sama, hal inidikarenakan perbedaan nilai Nu, Vu, dan Mu berdasarkan SNI 02-1726-2002 dan FEMA 450 sangatkecil. Secara umum, metode SNI 02-1726-2002 dan FEMA 450 memberikan perbedaan hasilperhitungan yang tidak signifikan.

Indonesian archipelago is located on a very active seismic zone, in which tsunami earthquake can happen in many location of the island. This tsunami earthquake can destroy city and town on the coast line. This tragedy will destroy and killed thousand peoples in the area. Because of this, a tsunami risk map have been developed, which will inform designers and goverment officials concerning tsunami runups in Indonesia. The tsunami risk map is based on the tsunami earthquake occurrence in the area, and the empirical formula by Katyusuki Abe (1995) for runups. Tsunami risk map was devided into 5 zone, that was zone 0 with α = 0,00 – 0,29, zone 1 with α = 0,30 – 0,49, zone 2 with α = 0,50 – 0,69, zone 3 with α = 0,70 – 0,89 and for zone 4, α = 0,90 – 1,10. Keywords : Tsunami, Runups, Maximum runrups, Base runups, Maximum base runups, Map, Zone coefficient.

In spite of extensive experimental and numerical investigations on steel shear walls, many ambiguities regarding the behavior of these walls still exist. One of these unknown characteristics, which have been less researched, is the effect of cracks on system behavior. Experimental studies have reported fracture on the corner of Steel Plate Shear Walls (SPSW) during testing. Therefore, the present paper deals with seismic performance of cracked SPSW in linear and nonlinear zones. The extended finite element method based on cohesive crack approach is used in Finite Element (FE) modeling. FE results indicated that small initial crack does not have considerable effect on the behavior of SPSW. Since SPSW is ruptured due to crack with long length, it cannot be utilized as a lateral resisting system in high seismic zone although long initial crack does not have a considerable effect on R-factor. Moreover, the horizontal crack is more effective than vertical crack. In addition, a method for predicting the trend of the load–displacement diagram has been proposed. The obtained results show a high convergence of the proposed approach with the results of the finite element method.

Cambay basin is one of the major onshore oil-bearing sedimentary basins of India situated at its western margin in Gujarat state. The region is seismically active and experiences three devastating earthquakes in the past. The region comes under the seismic zone IV and V and necessitates the extensive geophysical studies in for subsurface characteristics and identification of hidden faults in the region for seismic hazard estimation. A magnetotelluric (MT) survey has carried out in the southwestern part of the Cambay basin to identify the sedimentary thickness, the depth of Deccan trap and for identification of West Cambay margin that passes through the region. The MT data, at 13 stations, in the broad frequency range is acquired along an east-west profile with an inter-station spacing of 2–3 km. After processing and analysis of the data, transfer functions in the period band of 0.001–300 s are used for two-dimensional joint inversion. The resultant structure from the 2-D modeling infers the sedimentary thickness of ~0.5 km. A high conductive zone dipping towards east observed in the eastern part of the profile might be due to the West Cambay fault. Basement fracturing at a depth of 2.5–3.0 km at the central portion of the profile might act as a heat exchanger between the deeper geothermal source and nearby hot water spring.

Identification of precise hypocenter location is useful in order to improve the faults plane orientation and seismic zone analysis. In the study area, relocated hypocenter of earthquakes in Koyna-Warna region (KWR) from the short period recorded data from 6th January 2010 to 28th May 2010 by using Cross-Correlation waveform results in Double Difference Hypocenter method [1]. The results show the significant improvement in hypocenter location and orientation in earthquake hypocenters, which is correlated with local faults plane orientation in study region. From the observations the earthquake hypocenters are lying in the depth between 3 to 8 km. The result which identified three faults plane orientation in NNW-SSE direction and also identified new fractures in NE-SW directions between the faults plane orientation with short duration data sets the first time in India.

Traditional Probabilistic Seismic Hazard Analysis (PSHA) estimates the level of earthquake ground shaking that is expected to be exceeded with a given recurrence time on the basis of historical earthquake catalogues and empirical and time-independent Ground Motion Prediction Equations (GMPEs). The smooth nature of GMPEs usually disregards some well known drivers of ground motion characteristics associated with fault rupture processes, in particular in the near-fault region, complex source-site propagation of seismic waves, and sedimentary basin response. Modern physics-based earthquake simulations can consider all these effects, but require a large set of input parameters for which constraints may often be scarce. However, with the aid of high-performance computing (HPC) infrastructures the parameter space may be sampled in an efficient and scalable manner allowing for a large suite of site-specific ground motion simulations that approach the center, body and range of expected ground motions. CyberShake is a HPC platform designed to undertake physics-based PSHA from a large suite of earthquake simulations. These simulations are based on seismic reciprocity, rendering PSHA computationally tractable for hundreds of thousands potential earthquakes. For each site of interest, multiple kinematic rupture scenarios, derived by varying slip distributions and hypocenter location across the pre-defined fault system, are generated from an input Earthquake Forecast Model (EFM). Each event is simulated to determine ground motion intensities, which are synthesized into hazard results. CyberShake has been developed by the Southern California Earthquake Center, and used so far to assess seismic hazard in California. This work focuses on the CyberShake migration to the seismic region of South Iceland (63.5°- 64.5°N, 20°-22°W) where the largely sinistral East-West transform motion across the tectonic margin is taken up by a complex array of near-vertical and parallel North-South oriented dextral transform faults in the South Iceland Seismic Zone (SISZ) and the Reykjanes Peninsula Oblique Rift (RPOR). Here, we describe the main steps of migrating CyberShake to the SISZ and RPOR, starting by setting up a relational input database describing potential causative faults and rupture characteristics, and key sites of interest. To simulate our EFM, we use the open source code SHERIFS, a logic-tree method that converts the slip rates of complex fault systems to the corresponding annual seismicity rate. The fault slip rates are taken from a new 3D physics-based fault model for the SISZ-RPOR transform fault system. To validate model and simulation parameters, two validation steps using key CyberShake modeling tools have been carried out. First, we perform simulations of historical earthquakes and compare the synthetics with recorded ground motions and results from other forward simulations. Second, we adjust the rupture kinematics to make slip distributions more representative of SISZ-type earthquakes by comparing with static slip distributions of past significant earthquakes. Finally, we run CyberShake and compare key parameters of the synthetic ground motions with new GMPEs available for the study region. The successful migration and use of CyberShake in South Iceland is the first step of a full-scale physics-based PSHA in the region, and showcases the implementation of CyberShake in new regions.

About 25% of bridges in Craighead County, a part of Northeast Arkansas (NEA) in the United States of America, are in a poor condition. The NEA region is situated within a major seismic zine called the New Madrid Seismic Zone (NMSZ). In recent years, several new bridges have been proposed for new highways or improvement of existing highways within this zone. With the existing vulnerability due to the presence of the nearby active fault and higher seismic design force requirements, future investment in the repairment of bridges and new construction are critical issues. The main objectives of this study are to estimate seismic site coefficients for this zone by ground response analysis and compare them with coefficients recommended by researchers and agencies such as the American Association of State Highway Official (AASHTO). The shear wave velocity profiles (SWVP) of this zone have been collected from historical construction projects in the NEA and Mississippi Embayment (ME) areas. The seismic hazard analysis (SHA) has been carried out for different locations within this zone. Using a unified 1-D (one-dimension) equivalent linear (EQL) and nonlinear (NL) site response analyses platform called DEEPSOIL (Version 7.0), a series of ground response analyses has been carried out to evaluate possible variabilities of SWVPs, dynamic soil properties, and SHA results. Finally, seismic acceleration site coefficients have been estimated for selected locations within this zone. The findings of this study are expected to help the city and state highway design engineers to calculate design forces for existing and new bridges that will lead to the avoidance of expensive field investigations.

Municipalities and industries use the liquid storage tanks widely for water storage, storing inflammable liquids and various chemicals. There are primarily three types of tanks to store liquids namely underground tanks, ground supported tanks and elevated tanks. In this paper, the prime focus is on elevated water storage tanks. Water tanks are important strategic structures because they provide water to the mass of people and hence their behaviour during earthquakes must be studied in detail so that they do not undergo any huge damage due to the action of horizontal forces during an earthquake causing loss of life and property. Indian standard code IS 1893 (Part 2) helps to determine the dynamic behaviour of water tank by considering the movement of water in reference to the tank and the movement of the tank in reference to the ground. In this paper, a comparison has been made between three types of circular elevated water tanks under high seismic zone. These tanks are designed and seismically analysed using manual calculations as per IS 1893:2014 (Part 2) as well as STAAD Pro analysis using equivalent static method and response spectrum method. The tanks taken for comparison have the same capacity and parameters. This study focusses on determining the impact of geometry on water tank’s behaviour and response during an earthquake.

Liquefaction has always been a major concern in the field of geotechnical engineering. Construction of any structure on liquefiable soil is always expansive and thus leading to consumption of huge resources. In India, assessment of liquefaction potential is carried out using Indian standard code (IS 1893 Part 1, 2016). It is one the latest and simplest procedure based on field tests along with other parameters and does not consider plasticity of soil. But, based on numerous studies in past, a dependency of liquefaction potential with plasticity of soil is well documented. Thus, an attempt has been made to develop a multi-linear regression (MLR) model to predict factor of safety which considers the behavior of fine content of soil. The site considered in the present study lies near the bank of river Ganga and situated in zone IV (high seismic zone) of Bihar state of India. The mentioned site has been studied for its liquefaction potential using simplified deterministic procedure as per IS code method. The probability of liquefaction and reliability index (β) are determined using developed MLR model and reliability analysis. It is found that MLR model is more reliable and possess a lesser probability to liquefaction. The response obtained is mainly dependent of parameters like plasticity and fine content. Therefore, plasticity may be considered as a major discriminating criteria in the evaluation of liquefaction susceptibility.