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CONTENTS
Volume 23, Number 1, July 2022
 


Abstract
This study implements a hybrid Genetic Algorithm to detect, locate, and quantify structural damage for multistory shear buildings using partial modal data. Measuring modal responses at multiple locations on a structure is both challenging and expensive in practice. The proposed method's objective function is based on the building's dynamic properties and can also be employed with partial modal information. This method includes initial residuals between the numerical and experimental model and a damage penalization term to avoid false damages. To test the proposed method, a numerical example of a ten-story shear building with noisy and partial modal information was explored. The obtained results were in agreement with the previously published research. The proposed method's performance was also verified using experimental modal data of an 8-DOF spring-mass system and a five-story shear building. The predicted results for numerical and experimental examples indicated that the proposed method is reliable in identifying the damage for multistory shear buildings.

Key Words
damage detection; damage penalization; genetic algorithm; multistory buildings

Address
Ankur Shah: Civil Engineering Department, Sardar Vallabhbhai National Institute of Technology, Surat-395007, India
Gaurang Vesmawala: Civil Engineering Department, Sardar Vallabhbhai National Institute of Technology, Surat-395007, India
V. Meruane: Department of Mechanical Engineering, University of Chile, Santiago, Chile

Abstract
Masonry constructions exhibit uncertain behaviors under dynamic effects such as seismic action. Complex issues arise in the idealization of structural systems of buildings having different material types and mechanical properties. In this study, the structural behavior of a vaulted masonry building constructed using full clay brick and lime-based mortar and sitting on consecutive arches was investigated by experimental and numerical approaches. The dimensions of the structure built in the laboratory were 391 × 196 cm, and its height was 234 cm. An incremental repetitive loading was applied to the prototype construction model. Along the gradually increasing loading pattern, the load-displacement curves of the masonry structure were obtained with the assistance of eight linear displacement transducers. In addition, crack formation areas, and relevant causes of its formation were determined. The experimental model was idealized using the finite element method, and numerical analyses were performed for the area considered as linear being under similar loading effect. From the linear analyses, the displacement values and stress distribution of the numerical model were obtained. In addition, the effects of tie members, frequently being used in the supports of curved load-bearing elements, on the structural behavior were examined. Consequently, the experimental and numerical analysis results were comparatively evaluated.

Key Words
arch tie member; arched vaulted system; brick masonry; masonry construction

Address
Yunus Güner: Department of Civil Engineering, Ege University, Izmir, Turkey, Department of Civil Engineering, Ayd

Abstract
This paper presents experimental studies on reinforced concrete moment resisting frames that have engineered cementitious composite (ECC) in plastic hinge length (PHL) of beam/column members and beam-column joints. A two-story frame structure reduced by a 1:3 scale was further tested through a shake-table (seismic simulator) using multiple levels of simulated earthquake motions. One model conformed to all the ACI-318 requirements for IMRF, whereas the second model used lower-strength concrete in the beam/column members outside PHL. The acceleration time history of the 1994 Northridge earthquake was selected and scaled to multiple levels for shake-table testing. This study reports the observed damage mechanism, lateral strength-displacement capacity curve, and the computed response parameters for each model. The tests verified that nonlinearity remained confined to beam/column ends, i.e., member joint interface. Calculated response modification factors were 11.6 and 9.6 for the code-conforming and concrete strength deficient models. Results show that the RC-ECC frame's performance in design-based and maximum considered earthquakes; without exceeding maximum permissible drift under design-base earthquake motions and not triggering any unstable mode of damage/failure under maximum considered earthquakes. This research also indicates that the introduction of ECC in PHL of the beam/column members' detailing may be relaxed for the IMRF structures.

Key Words
composite structure; ductile frame; engineered cementitious composite (ECC); response modification factor; shake table tests

Address
Fasih A. Khan: Department of Civil Engineering, University of Engineering & Technology, Peshawar, Pakistan
Sajjad W. Khan: Department of Civil Engineering, University of Engineering & Technology, Peshawar, Pakistan
Khan Shahzada: Department of Civil Engineering, University of Engineering & Technology, Peshawar, Pakistan
Naveed Ahmad: Department of Civil Engineering, University of Engineering & Technology, Peshawar, Pakistan
Muhammad Rizwan: Department of Civil Engineering, University of Engineering & Technology, Peshawar, Pakistan
Muhammad Fahim: Department of Civil Engineering, University of Engineering & Technology, Peshawar, Pakistan
Muhammad Rashid: Department of Civil Engineering, University of Engineering & Technology, Peshawar, Pakistan

Abstract
This article presents a computationally efficient framework for multi-objective seismic design optimization of steel moment-resisting frame (MRF) structures based on the nonlinear dynamic analysis procedure. This framework employs the uniform damage distribution philosophy to minimize the weight (initial cost) of the structure at different levels of damage. The preliminary framework was recently proposed by the authors based on the single excitation and the nonlinear static (pushover) analysis procedure, in which the effects of record-to-record variability as well as higher-order vibration modes were neglected. The present study investigates the reliability of the previous framework by extending the proposed algorithm using the nonlinear dynamic design procedure (optimization under multiple ground motions). Three benchmark structures, including 4-, 8-, and 12-story steel MRFs, representing the behavior of low-, mid-, and high-rise buildings, are utilized to evaluate the proposed framework. The total weight of the structure and the maximum inter-story drift ratio (IDRmax) resulting from the average response of the structure to a set of seven ground motion records are considered as two conflicting objectives for the optimization problem and are simultaneously minimized. The results of this study indicate that the optimization under several ground motions leads to almost similar outcomes in terms of optimization objectives to those are obtained from optimization under pushover analysis. However, investigation of optimal designs under a suite of 22 earthquake records reveals that the damage distribution in buildings designed by the nonlinear dynamic-based procedure is closer to the uniform distribution (desired target during the optimization process) compared to those designed according to the pushover procedure.

Key Words
multi-objective optimization; nonlinear time history analysis; pushover analysis; steel moment frame buildings; uniform damage distribution; uniform damage optimization

Address
Ali Ghasemof: Department of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran
Masoud Mirtaheri: Department of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran
Reza Karami Mohammadi: Department of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran
Mojtaba Salkhordeh: Department of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran

Abstract
In this study, the seismic behavior of an all-steel buckling-restrained (AB) steel plate shear wall (SPSW) with incline slits under fire and cyclic loading was investigated. ABSPSW was composed of two thin steel infill plates with a narrow distance from each other, which were embedded with incline slits on each plate. These slits were in opposite directions to each other. The finite element (FE) numerical model was validated with three test specimens and after ensuring the modeling strategy, the parametric study was performed by considering variables such as wall plate thickness, slit width, strip width between two slits, and degree of temperature. A total of 256 FE numerical models were subjected to coupled temperature-displacement analysis. The results of the analysis showed that the high temperature reduced the seismic performance of the ABSPSW so that at 917◦C , the load-bearing capacity was reduced by 92%. In addition, with the increase in the temperature, the yield point of the infill plate and frame occurred in a small displacement. The average decrease in shear strength at 458◦C, 642◦C, and 917◦C was 18%, 46%, and 92%, respectively, compared to the shear strength at 20◦C. Also, with increasing the temperature to 917◦C, ductility increased by an average of 75%

Key Words
fire engineering; seismic engineering; steel structures; thermal effects

Address
Fereydoon Masoumi-Zahaneh: Department of Civil Engineering, Nour Branch Islamic Azad University, Nour, Iran
Mohamad Hoseinzadeh: Department of Civil Engineering, Nour Branch Islamic Azad University, Nour, Iran
Sepideh Rahimi: Department of Civil Engineering, Nour Branch Islamic Azad University, Nour, Iran
Mehdi Ebadi-Jamkhaneh: Department of Civil Engineering, School of Engineering, Damghan University, Damghan, Iran

Abstract
The megacity Istanbul was struck by an earthquake on September 26, 2019, with a moment magnitude (Mw) of 5.8. The mainshock was followed by many aftershocks. Although the peak ground acceleration (PGA) of the mainshock was as low as 0.08 g, its effect has been more than expected. The intensive reconnaissance studies were accomplished in the highly populated Zeytinburnu and Pendik districts of Istanbul. While the earthquake (EQ) was relatively smaller concerning record-specific intensity measures; the damages such as concrete spalling in reinforced concrete (RC) members, detachment and diagonal cracking of infill walls in RC frames as well as cracks in masonry structures were reported from non-engineered and some engineered buildings. Many studies in the literature state that record-specific intensity measures are not sufficient to evaluate the seismic performance of the structures. The structure-specific intensity measures, soil characteristics, as well as significant duration, energy, and frequency content of EQs should be considered for the evaluation. Dependently, the frequency and energy contents of the Istanbul Earthquake are evaluated to discuss the possible reasons for the perceived effects and the damages. It is concluded that the EQ caused resonance effects on a variety of structures because of its complex frequency content as well as rather low building quality.

Key Words
earthquake; frequency content; Istanbul; reconnaissance; seismic energy

Address
Ahmet Güllü: Ingram School of Engineering, Texas State University, San Marcos, TX, USA
Ercan Yüksel: Faculty of Civil Engineering, Istanbul Technical University 34469, Maslak, Istanbul, Turkey

Abstract
Limiting the displacement of seismic isolators causes a pounding phenomenon under severe earthquakes. Therefore, the ASCE 7-16 has provided minimum criteria for the design of the isolated building. In this research the seismic response of isolated buildings by Triple Friction Pendulum Isolator (TFPI) under the impact, expected, and unexpected mass eccentricity was evaluated. Also, the effect of different design parameters on the seismic behavior of structural and non-structural elements was found. For this, a special steel moment frame structure with a surrounding moat wall was designed according to the criteria, by considering different response modification coefficients (RI), and 20% mass eccentricity in one direction. Then, different values of these parameters and the damping of the base isolation were evaluated. The results show that the structural elements have acceptable behavior after impact, but the nonstructural components are placed in a moderate damage range after impact and the used improved methods could not ameliorate the level of damage. The reduction in the RI and the enhancement of the isolator's damping are beneficial up to a certain point for improving the seismic response after impact. The moat wall reduces torque and maximum absolute acceleration (MAA) due to unexpected enhancement of mass eccentricity. However, drifts of some stories increase. Also, the difference between the response of story drift by expected and unexpected mass eccentricity is less. This indicates that the minimum requirement displacement according to ASCE 7-16 criteria lead to acceptable results under the unexpected enhancement of mass eccentricity.

Key Words
base isolation; bi-direction ground motions; friction pendulum isolator; mass eccentricity; moat wall

Address
Ataallah Sadeghi Movahhed: Department of Civil Engineering, Shabestar Branch, Islamic Azad University, Shabestar, Iran
Saeid Zardari: Department of Civil Engineering, Istanbul Okan University, Istanbul, Turkey
Erol Şadoğlu: Department of Civil Engineering, Karadeniz Technical University, Trabzon, Turkey

Abstract
A new type of fabricated subway station construction technology can effectively solve these problems. For a new type of metro structure form, it is necessary to clarify its mechanical properties, especially the seismic performance. A soil-structure elastoplastic finite element model is established to perform three-dimensional nonlinear dynamic time-history analysis based on the first fabricated station structure-Yuanjiadian station of Changchun Metro Line 2, China. Firstly, the nonlinear seismic response characteristics of the fabricated and cast-in-place subway stations under different seismic wave excitations are compared and analyzed. Then, a comprehensive analysis of several important parameters that may affect the seismic response of fabricated subway stations is given. The results show that the maximum plastic strain, the interlayer deformation, and the internal force of fabricated station structures are smaller than that of cast-in-place structure, which indicates that the fabricated station structure has good deformation coordination capability and mechanical properties. The seismic responses of fabricated stations were mainly affected by the soil-structure stiffness ratio, the soil inertia effect, and earthquake load conditions rarely mentioned in cast-in-place stations. The critical parameters have little effect on the interlayer deformation but significantly affect the joints' opening distance and contact stress, which can be used as the evaluation index of the seismic performance of fabricated station structures. The presented results can better understand the seismic responses and guide the seismic design of the fabricated station.

Key Words
deformation coordination; fully fabricated subway station; mechanical characteristics; seismic response; three-dimensional nonlinear time history analysis

Address
Huafei Hea: School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China
Zhaoping Li: School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China


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