Seismic response

This thesis examines the effects of geometry on the seismic response of mineral deposits. Massive mineral deposits have comparable velocities to silicate rocks but are denser. Hence they are characterized by higher acoustic impedances which should cause strong seismic anomalies. However, mineral deposits cause only weak diffractions in seismic data because of their small sizes and complex geometries. Conventional data processing may fail to detect mineral deposits because it attenuates the diffractions. -- P-wave reflection coefficients for a density-driven acoustic impedance contrast are large near normal incidence. The SV-wave has a stronger reflection coefficient with a reversed phase compared with the P-wave coefficient beyond normal incidence. Hence, large source to receiver offsets cannot record strong P-wave responses if the acoustic impedance contrast is density-driven. This finding is important in that, while deep targets are sought, source to receiver offsets must be small...

We have revised our analysis of the SPIRE observations of 2MASSW J1207334-393254 (2M1207). Recent PACS observations show a bright source located ∼25 ′′ east of 2M1207. There are issues in terms of the detection/non-detection of the bright source when comparing the Spitzer, WISE, and PACS observations. It is apparently inconsistent, perhaps due to variability or low signal-to-noise of the data. We have looked into the possible misidentification of the target, and have revised the measured SPIRE fluxes and the disc parameters for 2M1207. We have also reviewed which among the various formation mechanisms of this system would still be valid.

Soil-structure interaction may play a major role in the seismic response of a bridge structure. Specifically, soil layers of low stiffness and strength may result in permanent displacement of the abutments and foundations, thus imposing important kinematic conditions to the bridge structure. A study to illustrate such phenomena is undertaken based on three-dimensional nonlinear dynamic finite-element ͑FE͒ modeling and analysis ͑for a specific bridge configuration under a given seismic excitation͒. A bridge-foundationground model is developed based on the structural configuration and local soil conditions of the Humboldt Bay Middle Channel Bridge. The FE model and nonlinear solution strategy are built in the open-source software platform OpenSees of the Pacific Earthquake Engineering Research Center. Based on the simulation results, the overall system seismic response behavior is examined, as well as local deformations/stresses at selected critical locations. It is shown that permanent ground deformation may induce settlement and longitudinal/ transversal displacements of the abutments and deep foundations. The relatively massive approach ramps may also contribute to this simulated damage condition, which imposes large stresses on the bridge foundations, supporting piers, and superstructure.

This paper presents an energy-based theoretical model for a two degree-of-freedom mechanical system. After a general formulation in Appendix A, the model is specialized to study tuned mass dampers as a means to substantially increase modal damping in order to induce a consequential decrease of the seismic response of the structures thus provided. Although approximate since it neglects coupling due to damping, it is shown that the model yields a ÿrst-order approximation to the exact frequencies, providing values of optimum damping that closely match exact results proposed by others. In view of this, it is proposed that the model be applied through an iterative numerical procedure that identiÿes the pertinent optimum parameters. It is also shown that for certain particular benchmark cases the model provides closed-form equations for the parameters deÿning the dynamic states related to these special conditions. Despite its approximate nature the model presented in this paper is rational, and due to its explicit consideration of energy balance and overall simplicity, it provides a convenient platform for the study of tuned mass dampers, as well as for other methods of structural passive control. Copyright

In the context of capacity design philosophy, where a desired failure mode exhibiting adequate levels of energy absorption capacity is envisaged, control must be exercised on the member behaviour to safeguard the achievement of the target overall response. ...

Results of an extensive numerical study on two-dimensional wave scattering by valleys of semi-elliptical cross-section due to incident SH, SV and P waves are presented. The investigation has been conducted using a rigorous boundary element algorithm. The influence of key parameters, such as, valley depth, iml~edance ratio, frequency, and angle of incidence on surface ground motion are studied in detail. Furthermore, the case of a valley within a layered half-space is analyzed and results compared with those obtained for a valley within a homogeneous half-space.

Past earthquakes have revealed detrimental effects of pounding on the seismic performance of conventional fixed-supported buildings, ranging from light local damage to more severe structural failure. However, the potential consequences of earthquake-induced poundings on seismically isolated buildings can be much more substantial, and, thus, should be assessed. This paper investigates, through numerical simulations, the effects of potential pounding incidences on the seismic response of a typical seismically isolated building. Such impact events may occur either with the surrounding moat wall at the building's base or against an adjacent building that may stand at a very close distance. A specialized software application has been developed in order to efficiently perform numerical simulations and parametric studies of this problem. The effects of certain parameters, such as the size of the separation distance, the characteristics of the adjacent structures and the earthquake characteristics, have been investigated using the developed software. The simulations have revealed that even if a sufficient gap is provided, with which poundings with the surrounding moat wall at the base of the building could be avoided, this does not ensure that the building will not eventually collide with neighboring buildings due to the deformations of their superstructures.

This paper provides an overview of the US Army Corps of Engineers' guidance for seismic design and evaluation of concrete dams, as presented in the Engineer Manual EM1110-2-6053. The re- quirements to design and evaluate concrete dams to have a predictable performance for specified levels of seismic hazard are discussed. The seismic input and performance levels associated with serviceability, damage control, and collapse prevention are defined. The analysis and evaluation procedures and acceptance criteria for each performance level are described. They consist of linear and nonlinear procedures for estimation of seismic response and acceptance criteria that use demand-capacity ratios, damage control thresholds, and irrecoverable level of movements and post-earthquake stability condition to assess dam safety. Finally, an example is provided to demonstrate the application of the manual to seismic evaluation of a concrete gravity dam.

The issue of gravity induced instability during response to severe seismic excitation is examined. It is contended that while static instability is fully determined by the existence of at least one negative eigenvalue in the second-order tangent stiffness, this condition is necessary, but not sufficient for instability during dynamic response. It is noted that the likelihood of collapse is strongly dependent on the shape of the mechanism that controls during the critical displacement cycle and that this shape can be reasonably identified using a pushover analysis with an appropriately selected lateral load distribution. A characterization of the instability limit state based on reduction of a multistorey building to an equivalent SDOF system is presented.

This paper reviews, compares, and contrasts the three methodologies proposed by C. A. Cornell, by Y. K. Wen, and by FEMA 273 (as proposed by H. Krawinkler) for predicting the postelastic response of buildings subject to seismic excitation. All three methods have the potential to contribute effectively to the problem of improving the practical prediction of seismic response of structures. Applications include preliminary design, routine (code) use, calibration of codes, and specific structure assessment. These methods appear different because their authors did not share the same objectives or information bases. The methods by Cornell and Wen are decisively prediction-oriented in explicitly probabilistic frameworks. The approach suggested by Krawinkler has instead the goal of understanding in some average sense the seismic response of structures at various performance levels. This last method has been adopted, however, for prediction purposes by the FEMA 273 Guidelines for rehabilitation of existing buildings. Despite the differences, the work proposed by these researchers is profitably brought under the same perspective here.

In the conventional design, buildings are generally considered to be fixed at their bases. In reality, flexibility of the supporting soil medium allows some movement of the foundation. This decreases the overall stiffness of the building frames resulting in a subsequent increase in the natural periods of the system and the overall response is altered. The present study considers low-rise building frames resting on shallow foundations, viz. isolated and grid foundation. Influence of soil-structure interaction on elastic and inelastic range responses of such building frames due to seismic excitations has been examined in details. Representative acceleration-time histories such as artificially generated earthquake history compatible with design spectrum, ground motion recorded during real earthquake and idealized near-fault ground motion, have been used to analyze the response. Variation in response due to different influential parameters regulating the effect of soil-flexibility is presented and interpreted physically. The study shows that the effect of soil-structure interaction may considerably increase such response at least for low-rise stiff structural system. q

measures. Summary This article reviews the ground motion parameters that can be assumed as structural and non-structural damage measures. Measures of seismic damage potential based on ground motion records are first described, followed by a discussion of the damage measures relating to simple (linear) and more complex (non-linear) structural responses. The second section reviews the measures of damage phenomena which

In this study an advanced capacity spectrum method (CSM), incorporating inelastic response history analysis is proposed. By employing inelastic response history analysis, the errors introduced due to the use of equivalent linear approaches are eliminated. The available variants of the CSM and the proposed method are used for the evaluation of the seismic response of a woodframe structure. The results are compared to experimental test data. It is observed that more accurate results are obtained with the method proposed in this paper, while the existing CSM approaches exhibited several shortcomings. These shortcomings include failure to predict the displacement demand, incompatibility between the demand and capacity diagrams and non-convergence. It is also observed that updating the bilinear idealization of the structural system according to the selected trial performance point on the capacity diagram significantly improves the accuracy of the CSM.

To predict the earthquake response of saturated porous media it is essential to correctly simulate the generation, redistribution, and dissipation of excess pore water pressure during and after earthquake shaking. To this end, a reliable numerical tool requires a dynamic, fully coupled formulation for solidfluid interaction and a versatile constitutive model. Presented in this paper is a 3D finite element framework that has been developed and utilized for this purpose. The framework employs fully coupled dynamic field equations with a u-p-U formulation for simulation of pore fluid and solid skeleton interaction and a SANISAND constitutive model for response of solid skeleton. After a detailed verification and validation of the formulation and implementation of the developed numerical tool, it is employed in the seismic response of saturated porous media. The study includes examination of the mechanism of propagation of the earthquake-induced shear waves and liquefaction phenomenon in uniform and layered profiles of saturated sand deposits.

This study summarizes state-of-the-art knowledge in the seismic response of vertically irregular building frames. Criteria defining vertical irregularity as per the current building codes have been discussed. A review of studies on the seismic behavior of vertically irregular structures along with their findings has been presented. It is observed that building codes provide criteria to classify the vertically irregular structures and suggest dynamic analysis to arrive at design lateral forces. Most of the studies agree on the increase in drift demand in the tower portion of set-back structures and on the increase in seismic demand for buildings with discontinuous distributions in mass, stiffness, and strength. The largest seismic demand is found for the combined-stiffness-and-strength irregularity.

The deployment of wireless sensor network (WSN) for continuous seismic monitoring system of cable-stayed bridge is presented in this paper. A newly developed WSN that is based on simultaneous high-speed concurrent transmission flooding technique was implemented on the Shin-Nakagawa Bridge, a 530-m single-plane, single-pylon, steel box girder, cable-stayed bridge in Ibaraki prefecture, eastern Japan. The structure is seismically isolated with laminated rubber bearings at the main pylon and piers. Some isolation bearings were partially damaged by the 2011 Great East Japan (Tohoku) earthquake. As a part of monitoring, a WSN with a total of 26 sensor nodes were installed at several locations on the piers, main pylon, girder, and ground. This paper describes the WSN system, the monitoring scheme and procedure, analysis of recorded seismic responses, and their use for structural assessment, especially the performance of isolation bearings during earthquakes. The monitoring system successfully recorded structural responses from 63 earthquakes in the 45 months monitoring period between August 2017 to December 2020, which include the responses from near-field and far-field earthquakes. The comparisons of recorded ground motions with existing nearby seismograph have shown the accuracy and reliability of the WSN. Modal parameters of the bridge were successfully determined from the seismic responses obtained from the WSN using multi-input multi-output time-domain system identifications. Characteristics of seismically isolated bridge responses, such as high-frequency filtering effect and decoupling effect of the girder responses, can be clearly observed from the records of the large earthquakes.

Flat-slab RC buildings exhibit several advantages over conventional moment-resisting frames. However, the structural effectiveness of flat-slab construction is hindered by its alleged inferior performance under earthquake loading. Although flat-slab systems are widely used in earthquake prone regions of the world, fragility curves for this type of construction are not available in the literature. This study focuses on the derivation of such fragility curves using medium-rise flat-slab buildings with masonry infill walls. The study employed a set of earthquake records compatible with the design spectrum selected to represent the variability in ground motion. Inelastic response-history analysis was used to analyze the random sample of structures subjected to the suite of records scaled in terms of displacement spectral ordinates, whilst monitoring four performance limit states. The fragility curves developed from this study were compared with the fragility curves derived for moment-resisting RC frames. The study concluded that earthquake losses for flat-slab structures are in the same range as for moment-resisting frames. Differences, however, exist. The study also showed that the differences were justifiable in terms of structural response characteristics of the two structural forms. #

The paper presents the results of numerical analyses carried out with FLAC finite difference code aiming at investigating the seismic response of rockfill dams. In particular the hysteretic damping model, recently incorporated within the code, coupled with a perfectly plastic yield criterion, was employed. As first step, 1D and 2D calibration analyses were performed and comparisons with the results supplied by well known linear equivalent and fully non linear codes were carried out. Then the seismic response of E1 Infiernillo rockfill dam was investigated during two weak and strong seismic events. Benefits and shortcomings of using the hysteretic damping model are discussed in the light of the results obtained from calibration studies and field-scale analyses.

The response modification factor plays a key role in the seismic design of new buildings in the United States. To date, the values assigned to this factor are based on engineering judgment and have little sound technical basis. Any improvement in the reliability of modern earthquake-resistant buildings in the United States will require the systematic evaluation of the building response characteristics that most affect the values assigned to the factor. To this end, a draft formulation that represents the response modification factor as the product of factors related to reserve strength, ductility, and redundancy is presented in the paper. Pertinent data from various analytical and experimental studies on reserve strength and ductility are also presented.

Dampers have become more popular recently for vibration control of structures, because of their safe, effective and economical design. This paper presents an overview of literature related to the behavior of dampers on seismically affected structures. The review includes different types of dampers like metallic dampers, viscoelastic dampers, frictional dampers etc.

This paper presents the main features and organization of CADAM, a computer program that has been developed for the static and seismic stability evaluations of concrete gravity dams. CADAM is based on the gravity method using rigid body equilibrium and beam theory to perform stress analyses, compute crack lengths, and safety factors. Seismic analyses could be done using either the pseudo-static or a simplified response spectrum method. CADAM is primarily designed to provide support for learning the principles of structural stability evaluation of gravity dams. It could also be used for research and development on stability of gravity dams. In adopting several worldwide published dam safety guidelines, a large number of modeling options have been implemented regarding (a) crack initiation and propagation, (b) effects of drainage and cracking under static, seismic, and post-seismic uplift pressure conditions, and (c) safety evaluation formats (deterministic allowable stresses and limit states, probabilistic analyses using Monte Carlo simulations). Structural stability evaluation of a 30m dam is presented to illustrate the use of CADAM that is available free from the web site:

XI Congresso Nazionale “L'ingegneria Sismica in Italia”, Genova 25-29 gennaio 2004 Vulnerabilità sismica di edifici in ca realizzati negli anni '70 A. Masi, M. Vona Dipartimento di Strutture, Geotecnica, Geologia applicata all'ingegneria, Università della Basilicata, Potenza, Italia ...

The existing medium height structures, constructed before 1970, are typically RC frames with masonry infill. These structures have been designed for gravity loads only and have little resistance for lateral loads caused by earthquakes. There exist many retrofitting methods for upgrading the seismic performance of such structures. The conventional retrofitting practices are generally invasive in character, to the existing structures and their occupants, hence not very acceptable to the occupancy. The concept of response control with tuned sloshing water dampers (TSWD) is one such promising option for improving the seismic resistance of these structures which is least invasive.
The central to the TSWD based retrofitting, of RC frame masonry infilled structures, is to reduce the displacement of the ES and avoidance of masonry failure during earthquake. The concept has been explained by example of an existing four story residential building. The structure has been discretised for three structural contribution conditions of masonry, i.e full contribution, no contribution and intermediate state where some part of masonry is contributing as diagonal compressive struts. The retrofitting propositions for all these three conditions have been made, analytically, with TSWD systems. It has been explained that for well-defined system subjected to harmonic excitations single frequency TSWDs (STSWD) may be optimally devised. For approximately assessed systems subjected to broad band excitations multiple frequency TSWDs (MTSWD) systems more robust.
The existing procedure for design of retrofitting system is iterative and cumbersome due to involvement of many approximately assessed parameters. Design charts for effectiveness of retrofitting system have been developed to obtain a quick estimate of mass ratio required for desired response reduction. Two simplified non-iterative methods have been developed one for accurately assessed and another for approximately assessed structures. These methods give a quick estimate of required mass ratio for desired performance.
The analytically made retrofitting propositions have been verified experimentally through the shake table tests on scaled model of the ES in coupling with TSWDs. The main feature of the experimental study is that ES has been scaled down dimensionally such that SM≡ES, but dynamic parameters of the structure have not been scaled and SM is equal to ES. The TSWD, tested with SMs in laboratory, is proposed for actual field execution.
The process of experimental validations of SM-TSWD interaction has been accomplished through 157 test runs. The interpretation of these experimental observations has led to simplified empirical correlations between relevant dynamic parameters of TSWD and ES. These empirical relations are valid for harmonic excitations only. However for broad band earthquake excitation the analytically devised propositions are only trend indicative and not valid. The robustness of the MTSWD system over STSWD system against earthquake excitations has been substantiated. An adequate factor of safety may be incorporated for applying the inferences from harmonic excitations to broad band excitations for MTSWD based retrofitting system. This study proposes a factor of safety 3.
Two non-dimensional parameters, as effectiveness ratio quantifying percentage response reduction and specific mass ratio defined as mass ratio required for one percentage effectiveness of the retrofitting system, for evaluating the performance of TSWD based retrofitting system have been introduced.
Since the analytical proposals are not valid for broad band excitations, it is proposed that for real life situations, the TSWD based retrofitting systems, should be designed on the basis of experimental evidence. A Hardware interactive soft path methodology for design of TSWD retrofitting system has been devised. As there is no scaling of dynamic properties between SM and ES and the TSWD used in coupling with SM has to be installed at ES, hence the experimental inferences of SM-TSWD coupling can be extrapolated to retrofitting of the ES, as ES-TSWD coupling. Thus a TSWD based retrofitting system may be designed for desired response reduction of ES.
The required sloshing water mass is to be accommodated in multiple TSWDs with their frequencies distributed around the frequency of ES. The system as a whole behaves as a robust multiple TSWD retrofitting regime with assurance of replicating laboratory performance in real life seismic eventuality.
From experimental observations for 25% effectiveness of TSWD system against broad band excitation the required mass ratio is 2.59% for SM and same is valid for ES also, accordingly an execution scheme has been proposed.
This research presents a simple and non-invasive retrofit scheme utilising tuned sloshing water dampers in RC frame masonry infilled structures. The design approach utilises the theoretical knowledge in conjunction with experimental verifications for TSWD based retrofitting system. The retrofitting with TSWDs may be accomplished by modifying the existing overhead tank and installing additional tanks of optimally tuned geometry for desired response reduction. The installation of TSWD based retrofitting system provides all time preparedness against earthquake, without interfering with the structural, architectural and occupancy requirements. The proposed TSWD based retrofitting system essentially a technique of absorbing seismic energy through sloshing action of water.

This paper presents the results of shaking table tests on model reinforced soil retaining walls in the laboratory. The influence of backfill relative density on the seismic response was studied through a series of laboratory model tests on retaining walls. Construction of model retaining walls in the laminar box mounted on shaking table, instrumentation and results from the shaking table tests are described in detail. Three types of walls: wrap-and rigid-faced reinforced soil walls and unreinforced rigid-faced walls constructed to different densities were tested for a relatively small excitation. Wrap-faced walls are further tested for higher base excitation at different frequencies and relative densities. It is observed from these tests that the effect of backfill density on the seismic performance of reinforced retaining walls is pronounced only at very low relative density and at the higher base excitation. The walls constructed with higher backfill relative density showed lesser face deformations and more acceleration amplifications compared to the walls constructed with lower densities when tested at higher base excitation. The response of wrap-and rigid-faced retaining walls is not much affected by the backfill relative density when tested at smaller base excitation. The effects of facing rigidity were evaluated to a limited extent. Displacements in wrap-faced walls are many times higher compared to rigid-faced walls. The results obtained from this study are helpful in understanding the relative performance of reinforced soil retaining walls constructed to when subjected to smaller and higher base excitation for the range of relative density employed in the testing program. r

A comprehensive study carried out to assess the seismic response of a 59-span bridge using a refined inelastic modeling approach and considering Soil-Structure Interaction (SSI) is summarized in this paper. The focus is on describing the methodology adopted to idealize the bridge and its foundation system, while only highlights from the extensive elastic and inelastic analyses are presented. The bridge represents a typical case of vulnerable complex bridges since it was built in the early seventies with minimal seismic design requirements at a distance of about 5 km from a major fault. The SSI analysis is significant in this study due to the length of the bridge, the massive and stiff foundation, and the relatively soft deep soil of the site. A series of three-dimensional dynamic response simulations of the entire bridge are conducted using several analysis tools to verify the developed analytical models. The performance-based assessment study employs 144 site-specific input ground motions representing three seismic scenarios, corresponding to 500, 1000 and 2500 years return periods, to identify areas of vulnerability in the 2164-meter bridge at various hazard levels. It is concluded that the seismic response of the bridge at the 500 years ground motions does not meet today's standards, while the demands under the effect of the 1000 years ground motions almost exceed the capacity of most bridge components. The demands significantly increase under the effect of the 2500 years earthquake scenario and considerably exceed the collapse limit states. The results clearly reflect the benefit of retrofitting different bridge components to mitigate the anticipated seismic risk. The presented assessment study contributes to improve public safety by exploiting the most recent research outcomes in predicting the seismic response of complex highway bridges, which are essential for developing reliable and cost-effective retrofit strategies.

The main objective of this research is to develop a better understanding of the applications of various seismic response modification technologies to protect structural and nonstructural systems and components in acute care facilities from the effects of earthquakes. A secondary objective of the research is to establish a relationship between the performance of nonstructural components and structural demands in order to optimize and harmonize performance objectives between structural and nonstructural systems and components in acute care facilities. A broad range of seismic response modification technologies are under investigation, from those close to implementation to others that require long-term investigation. Results of analytical and experimental studies are being used in fragility studies to probabilistically quantify the relative merits and potential benefits to structural and nonstructural component of implementing these technologies. Eventually, the results will be quantified and included in decision support methodologies that integrate both engineering and social science aspects.

The current design of supporting structure of Elevated water tanks is tremendously vulnerable under lateral forces due to an earthquake. Water tanks and especially the elevated water tanks are structures of high importance which are considered as main lifeline elements that should be capable of keeping the expected performance i.e. operation during and after earthquakes. Thus researchers, in recent years, have focused on studying seismic behaviors of these tanks, particularly ground tanks, while only few of these researches have concerned with the elevated tanks and even less with the reinforced concrete elevated tanks. In this research, a sample of a concrete elevated water tank with 400 m3 have been studied and analyzed by linear dynamic method and seismic response such as base shear, tank displacement, max Bending Moment at the base of column under tank reinforced empty condition, tank full condition and tank half full condition for different type of bracing arrangements have been calculated and then results have been compared.

This paper describes a range of geophysical research activities at the Australian Resources Research Centre based around the development of an experimental capability to validate theoretical and numerical modelling predictions of geophysical properties of reservoirs and seals. Laboratory tests performed on reservoir sandstones, shales and artificial sandstones under a range of controlled triaxial stress conditions allow the full anisotropic elastic tensor to be calculated from ultrasonic measurements on a single core. The analysis of elastic properties and anisotropy in relation to varied stress, pore pressure and fluid saturation can provide significant insight for both exploration (e.g. pore pressure prediction) and production (4D seismic feasibility studies for changes in pore pressure and saturation during production). Ultrasonic data from core measurements are related to seismic response through theoretical analysis of frequency effects and the methodologies developed from this research are subsequently tested on 3D seismic data. Understanding the causes and degree of anisotropy, for example, are critical for depth conversion, imaging, fluid identification (e.g. AVO) and dynamic Poisson's ratio.

Structural response control, with tuned sloshing water dampers (TSWD) may be adopted as seismic
retrofitting measure for the existing structures (ES).The water tanks of designed geometry rigidly attached with the
ES at strategic locations behave as TSWD. Response reduction during earthquake is affected by energy dissipated
through sloshing of water mass.
The energy dissipation is dependent on mutual tuning of ES and TSWD, mass ratio, damping ratio of
TSWD and damping ratio of ES. Larger the mass ratio more will be the response reduction. Mutual dependency and
uncertainties involved with the assessment of dynamic properties of ES make the design process of retrofitting
system iterative and cumbersome.
Multiple dampers, with their frequencies distributed around the first mode frequency of ES, shall perform
more robustly. The desired mass ratio may be accommodated in multiple tanks. The geometry of these tanks may be
moderated in such a way that it behaves as multiple dampers. The multiple TSWD system will overcome the errors
due to assessment approximations of dynamic properties of ES and TSWD.
The performance of the retrofitting system is assessed by reduction in maximum structural displacement
affected. Design charts in the form of effectiveness ratio, depicting the performance of TSWDs, have been presented
which reduces iterative computational effort. The retrofitting methodology is explained by example of an existing
four story structure. The effectiveness and robust performance of multiple TSWD has been demonstrated. The
method ensures all time preparedness of the ES, without occupancy and structural interference, against earthquake.

Structural frames are often filled with infilled walls serving as partitions. Although the infills usually are not considered in the structural analysis and design, their influence on the seismic behaviour of the infilled frame structures is considerable. In the present study, a parametric study of certain infilled frames, using the strut model to capture the global effects of the infills was carried out. Three concrete planar frames of five-stories and three-bays are considered which have been designed in accordance with Turkish Codes. Pushover analysis is adopted for the evaluation of the seismic response of the frames. Each frame is subjected to four different loading cases. The results of the cases are briefly presented and compared. The effect of infill walls on seismic behavior of two sample frames with different infill arrangements was investigated. The results yield that it is essential to consider the effect of masonry infills for the seismic evaluation of moment-resisting RC frames, especially for the prediction of its ultimate state, infills having no irregularity in elevation have beneficial effect on buildings and infills appear to have a significant effect on the reduction of global lateral displacements.

Steel I-beam, brick jack arch slabs have long been used to floor and roof industrial and residential buildings in many parts of the world. Collapse of a large number of these non-homogeneous one-way slabs during past earthquakes has highlighted their poor seismic performance. However, due to their easy construction together with low cost, the jack-arch slab is still widely used in many countries. In this article, the weaknesses inherent in the traditional one-way jack-arch slabs are explored. To overcome these shortcomings, a new two-way system is proposed. Results of static and dynamic tests on full scale two-way and one-way jack-arch slabs and finite element numerical analyses, aimed at investigating the effectiveness of the proposed two-way system, are presented with favourable conclusions. Following these investigations the static and seismic design of jack arch slabs are discussed. The proposed, allowable stress design method is based on designing for the steel grid and controlling the stresses in brick arches. Parameters necessary for an equivalent static seismic load calculation are first determined. Finite element numerical analyses are then conducted to investigate the effects of a number of parameters on the design of the slab and the necessary design factors are evaluated. In addition, appropriate tables and figures are presented to facilitate the design of the one-way and two-way jack arch slabs. It is concluded that the jack arch slab system, designed and constructed as presented in this article, provides a viable, low cost alternative to other forms of flooring in seismic zones and elsewhere. 

This paper presents a review of supplemental damping devices used for the control of the seismic response of structures. The mechanical properties of these devices are discussed and considerations in the design of energy absorbing systems are presented.

The eects of a rigid bae on the seismic response of liquid in a rigid cylindrical tank are presented. A bae is an additional structural element which supplies a kind of passive control on the eects of earthquake motion. Fluid motion is assumed to be irrotational, incompressible and inviscid. The method of superposition of modes has been implemented to compute the seismic response. The boundary element method is used to evaluate the natural modes of liquid in a cylindrical tank. Linearized free surface conditions have been taken into consideration.

This paper critically reviews seismic design practices in light of the observed performance of landfills during recent earthquakes. Developments in these areas are summarized as follows: earthquake ground motions, dynamic waste fill properties, dynamic responses of geomembranes and their interfaces, nonlinear dynamic response analysis, and seismic stability evaluation. A newly developed simplified seismic analysis procedure that requires the most critical factors be addressed during a seismic performance evaluation is presented. The underlying seismic analysis procedure has been validated against observed performance of landfills shaken by the 1989 Loma Prieta and 1994 Northridge, California earthquakes. The procedure is comprehensive in that it requires: (i) characterization of the design bedrock motions in terms of intensity, frequency content, and duration; (ii) estimation of the seismic loading at the base and cover of the landfill; (iii) evaluation of performance in terms of seismically induced permanent deformations; and (iv) appropriate engineering judgment.