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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Earthquakes and Structures
Journal Basic Information
Journal DOI :
Editor in Chief :
Izuru Takewaki / Stavros A. / Anagnostopoulos / Jerome P. Lynch
Volume & Issues
Volume 11, Issue 3 - Sep 2016
Volume 11, Issue 2 - Aug 2016
Volume 11, Issue 1 - Jul 2016
Volume 10, Issue 6 - Jun 2016
Volume 10, Issue 5 - May 2016
Volume 10, Issue 4 - Apr 2016
Volume 10, Issue 3 - Mar 2016
Volume 10, Issue 2 - Feb 2016
Volume 10, Issue 1 - Jan 2016
Selecting the target year
Study on seismic retrofit of structures using SPSW systems and LYP steel material
Zirakian, Tadeh ; Zhang, Jian ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 1~23
DOI : 10.12989/eas.2016.10.1.001
Steel plate shear walls (SPSWs) have been shown to be efficient lateral force-resisting systems, which are increasingly used in new and retrofit construction. These structural systems are designed with either stiffened and stocky or unstiffened and slender web plates based on disparate structural and economical considerations. Based on some limited reported studies, on the other hand, employment of low yield point (LYP) steel infill plates with extremely low yield strength, and high ductility as well as elongation properties is found to facilitate the design and improve the structural behavior and seismic performance of the SPSW systems. On this basis, this paper reports system-level investigations on the seismic response assessment of multi-story SPSW frames under the action of earthquake ground motions. The effectiveness of the strip model in representing the behaviors of SPSWs with different buckling and yielding properties is primarily verified. Subsequently, the structural and seismic performances of several code-designed and retrofitted SPSW frames with conventional and LYP steel infill plates are investigated through detailed modal and nonlinear time-history analyses. Evaluation of various seismic response parameters including drift, acceleration, base shear and moment, column axial load, and web-plate ductility demands, demonstrates the capabilities of SPSW systems in improving the seismic performance of structures and reveals various advantages of use of LYP steel material in seismic design and retrofit of SPSW systems, in particular, application of LYP steel infill plates of double thickness in seismic retrofit of conventional steel and code-designed SPSW frames.
An efficient seismic analysis of regular skeletal structures via graph product rules and canonical forms
Kaveh, A. ; Zakian, P. ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 25~51
DOI : 10.12989/eas.2016.10.1.025
In this study, graph product rules are applied to the dynamic analysis of regular skeletal structures. Graph product rules have recently been utilized in structural mechanics as a powerful tool for eigensolution of symmetric and regular skeletal structures. A structure is called regular if its model is a graph product. In the first part of this paper, the formulation of time history dynamic analysis of regular structures under seismic excitation is derived using graph product rules. This formulation can generally be utilized for efficient linear elastic dynamic analysis using vibration modes. The second part comprises of random vibration analysis of regular skeletal structures via canonical forms and closed-form eigensolution of matrices containing special patterns for symmetric structures. In this part, the formulations are developed for dynamic analysis of structures subjected to random seismic excitation in frequency domain. In all the proposed methods, eigensolution of the problems is achieved with less computational effort due to incorporating graph product rules and canonical forms for symmetric and cyclically symmetric structures.
Passive 3D motion optical data in shaking table tests of a SRG-reinforced masonry wall
De Canio, Gerardo ; de Felice, Gianmarco ; De Santis, Stefano ; Giocoli, Alessandro ; Mongelli, Marialuisa ; Paolacci, Fabrizio ; Roselli, Ivan ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 53~71
DOI : 10.12989/eas.2016.10.1.053
Unconventional computer vision and image processing techniques offer significant advantages for experimental applications to shaking table testing, as they allow the overcoming of most typical problems of traditional sensors, such as encumbrance, limitations in the number of devices, range restrictions and risk of damage of the instruments in case of specimen failure. In this study, a 3D motion optical system was applied to analyze shake table tests carried out, up to failure, on a natural-scale masonry structure retrofitted with steel reinforced grout (SRG). The system makes use of wireless passive spherical retro-reflecting markers positioned on several points of the specimen, whose spatial displacements are recorded by near-infrared digital cameras. Analyses in the time domain allowed the monitoring of the deformations of the wall and of crack development through a displacement data processing (DDP) procedure implemented ad hoc. Fundamental frequencies and modal shapes were calculated in the frequency domain through an integrated methodology of experimental/operational modal analysis (EMA/OMA) techniques with 3D finite element analysis (FEA). Meaningful information on the structural response (e.g., displacements, damage development, and dynamic properties) were obtained, profitably integrating the results from conventional measurements. Furthermore, the comparison between 3D motion system and traditional instruments (i.e., displacement transducers and accelerometers) permitted a mutual validation of both experimental data and measurement methods.
Effect of connection rotation capacities on seismic performance of IMF systems
Han, Sang Whan ; Moon, Ki-Hoon ; Ha, Sung Jin ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 73~89
DOI : 10.12989/eas.2016.10.1.073
The seismic performance of moment frames could vary according to the rotation capacity of their connections. The minimum rotation capacity of moment connections for steel intermediate moment frames (IMF) was defined as 0.02 radian in AISC 341-10. This study evaluated the seismic performance of IMF frames with connections having a rotation capacity of 0.02 radian. For this purpose, thirty IMFs were designed according to current seismic design provisions considering different design parameters such as the number of stories, span length, and seismic design categories. The procedure specified in FEMA P695 was used for conducting seismic performance evaluation. It was observed that the rotation capacity of 0.02 radian could not guarantee the satisfactory seismic performance of IMFs. This study also conducted seismic performance evaluation for IMFs with connections having the rotation capacity of 3% and ductile connections for proposing the minimum rotation capacity of IMF connections.
Modeling of SH-waves in a fiber-reinforced anisotropic layer
Kakar, Rajneesh ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 91~104
DOI : 10.12989/eas.2016.10.1.091
In this paper we investigate the existence of SH-waves in fiber-reinforced layer placed over a heterogeneous elastic half-space. The heterogeneity of the elastic half-space is caused by the exponential variations of density and rigidity. As a special case when both the layers are homogeneous, our derived equation is in agreement with the general equation of Love wave. Numerically, it is observed that the velocity of SH-waves decreases with the increase of heterogeneity and reinforced parameters. The dimensionless phase velocity of SH-waves increases with the decreases of dimensionless wave number and shown through figures.
Probabilistic seismic evaluation of buckling restrained braced frames using DCFD and PSDA methods
Asgarian, Behrouz ; Golsefidi, Edris Salehi ; Shokrgozar, Hamed Rahman ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 105~123
DOI : 10.12989/eas.2016.10.1.105
In this paper, using the probabilistic methods, the seismic demand of buckling restrained braced frames subjected to earthquake was evaluated. In this regards, 4, 6, 8, 10, 12 and 14-storybuildings with different buckling restrained brace configuration (including diagonal, split X, chevron V and Inverted V bracings) were designed. Because of the inherent uncertainties in the earthquake records, incremental dynamical analysis was used to evaluate seismic performance of the structures. Using the results of incremental dynamical analysis, the "capacity of a structure in terms of first mode spectral acceleration", "fragility curve" and "mean annual frequency of exceeding a limit state" was determined. "Mean annual frequency of exceeding a limit state" has been estimated for immediate occupancy (IO) and collapse prevention (CP) limit states using both Probabilistic Seismic Demand Analysis (PSDA) and solution "based on displacement" in the Demand and Capacity Factor Design (DCFD) form. Based on analysis results, the inverted chevron (
) buckling restrained braced frame has the largest capacity among the considered buckling restrained braces. Moreover, it has the best performance among the considered buckling restrained braces. Also, from fragility curves, it was observed that the fragility probability has increased with the height.
Retrofitting of squat masonry walls by FRP grids bonded by cement-based mortar
Popa, Viorel ; Pascu, Radu ; Papurcu, Andrei ; Albota, Emil ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 125~139
DOI : 10.12989/eas.2016.10.1.125
For seismic retrofitting of masonry walls, the use of fibre reinforced cement-based mortar for bonding the fibre grids can eliminate some of the shortcomings related to the use of resin as bonding material. The results of an experimental testing program on masonry walls retrofitted with fibre reinforced mortar and fibre grids are presented in this paper. Seven squat masonry walls were tested under unidirectional lateral displacement reversals and constant axial load. Steel anchors were used to increase the effectiveness of the bond between the fibre grids and the masonry walls. Application of fibre grids on both lateral faces of the walls effectively improved the hysteretic behaviour and specimens could be loaded until slip occurred in the horizontal joint between the masonry and the bottom concrete stub. Application of the fibre grids on a single face did not effectively improve the hysteretic behaviour. Retrofitting with fibre reinforced mortar only prevented the early damage but did not effectively increase deformation capacity. When the boundaries of the cross sections were not properly confined, midplane splitting of the masonry walls occurred. Steel anchors embedded in the walls in the corners area effectively prevented this type of failure.
Estimating uncertainty in limit state capacities for reinforced concrete frame structures through pushover analysis
Yu, Xiaohui ; Lu, Dagang ; Li, Bing ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 141~161
DOI : 10.12989/eas.2016.10.1.141
In seismic fragility and risk analysis, the definition of structural limit state (LS) capacities is of crucial importance. Traditionally, LS capacities are defined according to design code provisions or using deterministic pushover analysis without considering the inherent randomness of structural parameters. To assess the effects of structural randomness on LS capacities, ten structural parameters that include material strengths and gravity loads are considered as random variables, and a probabilistic pushover method based on a correlation-controlled Latin hypercube sampling technique is used to estimate the uncertainties in LS capacities for four typical reinforced concrete frame buildings. A series of ten LSs are identified from the pushover curves based on the design-code-given thresholds and the available damage-controlled criteria. The obtained LS capacities are further represented by a lognormal model with the median
and the dispersion
. The results show that structural uncertainties have limited influence on
for the LSs other than that near collapse. The commonly used assumption of
between 0.25 and 0.30 overestimates the uncertainties in LS capacities for each individual building, but they are suitable for a building group with moderate damages. A low uncertainty as
is adequate for the LSs associated with slight damages of structures, while a large uncertainty as
is suggested for the LSs near collapse.
Cyclic tests of steel frames with composite lightweight infill walls
Hou, Hetao ; Chou, Chung-Che ; Zhou, Jian ; Wu, Minglei ; Qu, Bing ; Ye, Haideng ; Liu, Haining ; Li, Jingjing ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 163~178
DOI : 10.12989/eas.2016.10.1.163
Composite Lightweight (CL) insulated walls have gained wide adoption recently because the exterior claddings of steel building frames have their cost effectiveness, good thermal and structural efficiency. To investigate the seismic behavior, lateral stiffness, ductility and energy dissipation of steel frames with the CL infill walls, five one-story one-bay steel frames were fabricated and tested under cyclic loads. Test results showed that the bolted connections allow relative movement between CL infill walls and steel frames, enabling the system to exhibit satisfactory performance under lateral loads. Additionally, it is found that the addition of diagonal steel straps to the CL infill wall significantly increases the initial lateral stiffness, load-carrying capacity, ductility and energy dissipation capacity of the system. Furthermore, the test results indicate that the lateral stiffness values of the frames with the CL infill wall are similar to those of the bare steel frames in large lateral displacement.
Seismic bearing capacity of shallow footings on cement-improved soils
Kholdebarin, Alireza ; Massumi, Ali ; Davoodi, Mohammad ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 179~190
DOI : 10.12989/eas.2016.10.1.179
A single rigid footing constructed on sandy-clay soil was modeled and analyzed using FLAC software under static conditions and vertical ground motion using three accelerograms. Dynamic analysis was repeated by changing the elastic and plastic parameters of the soil by changing the percentage of cement grouting (2, 4 and 6 %). The load-settlement curves were plotted and their bearing capacities compared under different conditions. Vertical settlement contours and time histories of settlement were plotted and analyzed for treated and untreated soil for the different percentages of cement. The results demonstrate that adding 2, 4 and 6 % of cement under specific conditions increased the dynamic bearing capacity 2.7, 4.2 and 7.0 times, respectively.
Seismic force evaluation of RC shear wall buildings as per international codes
Jayalekshmi, B.R. ; Chinmayi, H.K. ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 191~209
DOI : 10.12989/eas.2016.10.1.191
Seismic codes are the best available guidance on how structures should be designed and constructed to ensure adequate resistance to seismic forces during earthquakes. Seismic provisions of Indian standard code, International building code and European code are applied for buildings with ordinary moment resisting frames and reinforced shear walls at various locations considering the effect of site soil conditions. The study investigates the differences in spectral acceleration coefficient (
), base shear and storey shear obtained following the seismic provisions in different codes in the analysis of these buildings. Study shows that the provision of shear walls at core in low rise buildings and at all the four corners in high rise buildings gives the least value of base shear.
Combination rules and critical seismic response of steel buildings modeled as complex MDOF systems
Reyes-Salazar, Alfredo ; Valenzuela-Beltran, Federico ; de Leon-Escobedo, David ; Bojorquez-Mora, Eden ; Barraza, Arturo Lopez ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 211~238
DOI : 10.12989/eas.2016.10.1.211
The Maximum seismic responses of steel buildings with perimeter moment resisting frames (MRF), modeled as complex MDOF systems, are estimated for several incidence angles of the horizontal components and the critical one is identified. The accuracy of the existing rules to combine the effects of the individual components is also studied. Two and three components are considered. The critical response does not occur for principal components and the corresponding incidence angle varies from one earthquake to another. The critical response can be estimated as 1.40 and 1.10 times that of the principal components, for axial load and interstory shears, respectively. The rules underestimate the axial load but reasonably overestimate the shears. The rules are not always inaccurate in the estimation of the combined response for correlated components. On the other hand, totally uncorrelated (principal) components are not always related to an accurate estimation. The correlation of the individual effects (
) may be significant, even for principal components. The rules are not always associated to an inaccurate estimation for large values of
, and small values of
are not always related to an accurate estimation. Only for perfectly uncorrelated harmonic excitations and elastic analysis of SDOF systems, the individual effects of the components are uncorrelated and the rules accurately estimate the combined response. The degree of correlation of the components, the type of structural system, the response parameter under consideration, the location of the structural member and the level of structural deformation must be considered while estimating the level of underestimation or overestimation.
Effectiveness of design procedures for linear TMD installed on inelastic structures under pulse-like ground motion
Quaranta, Giuseppe ; Mollaioli, Fabrizio ; Monti, Giorgio ;
Earthquakes and Structures, volume 10, issue 1, 2016, Pages 239~260
DOI : 10.12989/eas.2016.10.1.239
Tuned mass dampers (TMDs) have been frequently proposed to mitigate the detrimental effects of dynamic loadings in structural systems. The effectiveness of this protection strategy has been demonstrated for wind-induced vibrations and, to some extent, for seismic loadings. Within this framework, recent numerical studies have shown that beneficial effects can be achieved by placing a linear TMD on the roof of linear elastic structural systems subjected to pulse-like ground motions. Motivated by these positive outcomes, closed-form design formulations have been also proposed to optimize the device's parameters. For structural systems that undergo a near-fault pulse-like ground motion, however, it is unlikely that their dynamic response be linear elastic. Hence, it is very important to understand whether such strategy is effective for inelastic structural systems. In order to provide new useful insights about this issue, the paper presents statistical results obtained from a numerical study conducted for three shear-type hysteretic (softening-type) systems having 4, 8 and 16 stories equipped with a linear elastic TMD. The effectiveness of two design procedures is discussed by examining the performances of the protected systems subjected to 124 natural pulse-like earthquakes.