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CONTENTS
Volume 22, Number 1, January 2022
 


Abstract
When a building suffers damages under moderate to severe loading condition, its physical properties such as damping and stiffness parameters will change. There are different practical methods besides various numerical procedures that have successfully detected a range of these changes. Almost all the previous proposed methods used to work with translational components of mode shapes, probably because extracting these components is more common in vibrational tests. This study set out to investigate the influence of using both rotational and translational components of mode shapes, in detecting damages in 3-D steel structures elements. Three different sets of measured components of mode shapes are examined: translational, rotational, and also rotational/translational components in all joints. In order to validate our assumptions two different steel frames with three damage scenarios are considered. An iterative model updating program is developed in the MATLAB software that uses the OpenSees as its finite element analysis engine. Extensive analysis shows that employing rotational components results in more precise prediction of damage location and its intensity. Since measuring rotational components of mode shapes still is not very convenient, modal dynamic expansion technique is applied to generate rotational components from measured translational ones. The findings indicated that the developed model updating program is really efficient in damage detection even with generated data and considering noise effects. Moreover, methods which use rotational components of mode shapes can predict damage's location and its intensity more precisely than the ones which only work with translational data.

Key Words
damage detection method; iterative optimization method; modal dynamic expansion method; model updating method; rotational DOFs; translational DOFs

Address
Zahra Toorang: Structural Engineering Research Center, International Institute of Earthquake Engineering & Seismology (IIEES), Iran

Omid Bahar: Structural Engineering Research Center, International Institute of Earthquake Engineering & Seismology (IIEES), Iran

Fariborz Nateghi Elahi: Structural Engineering Research Center, International Institute of Earthquake Engineering & Seismology (IIEES), Iran

Abstract
One of the key tools in assessing the seismic vulnerability of the structures is the use of fragile functions, which is the possibility of damage from a particular damage surface for several levels of risk from the seismic movements of the earth. The aim of this study is to investigate the effect of two categories of earthquake events on the fragile curve (FRC) of the steel construction system. In this study, the relative lateral displacement of the structures is considered as a damage criterion. The limits set for modifying the relative lateral position in the HAZUS instruction are used to determine the failure modes, which include: slight, moderate, extensive and complete. The results show, as time strong-motion increases, the probability of exceeding (PoE) increases (for Peak ground acceleration (PGA) less than 0.5). The increase in seismic demand increases the probability of exceeding. In other words, it increases the probability of exceeding, if the maximum earthquake acceleration increases. Also, 7-storey model in extensive mode has 20 and 26.5% PoE larger than 5- and 3-storey models, respectively.

Key Words
fragile curves; incremental dynamic analysis (IDA); probability of exceeding; steel structures

Address
Feipeng Wang: Department of Architecture and Civil Engineering, Yuncheng Vocational and Technical University, Yunchen,044000

Jie Miao: Department of Architecture and Civil Engineering, Yuncheng Vocational and Technical University, Yunchen,044000, China

Zhichun Fang: School of civil engineering, Shijiazhuag Tiedao University, Shijiazhuang 050043, China

Siqi Wu: School of traffic and transportation, Shijiazhuag Tiedao University, Shijiazhuang 050043, China

Xulong Li: School of civil engineering, Shijiazhuag Tiedao University, Shijiazhuang 050043, China

Younes Momeni: Tabriz Branch, Islamic Azad University, Tabriz, Iran

Abstract
The RC private constructions represent a large part of the housing stock in the north part of Algeria. For various reasons, they are mostly built without any seismic considerations and their seismic vulnerability remains unknown for different levels of seismic intensity possible in the region. To support future seismic risk mitigation efforts in northern Algeria, this document assesses the seismic vulnerability of typical private RC constructions built after the Boumerdes earthquake (May 21, 2003) without considering existing seismic regulation, through the development of analytical fragility curves. The fragility curves are developed for four representative RC frames in terms of slight, moderate, extensive, and complete damage states suggested in HAZUS-MH 2.1, using nonlinear time history analyses. The numerical simulation of the nonlinear seismic response of the structures is performed using the SeismoStruct software. An original intensity measure (IM) is proposed and used in this study. It is the zone acceleration coefficient “A”, through which the seismic hazard level is represented in the Algerian Seismic Regulations. The efficiency, practicality, and proficiency of the choice of IM are demonstrated. Incremental dynamic analyses are conducted under fifteen ground motion accelerograms compatible with the elastic target spectrum of the Algerian Seismic Regulations. In order to cover all the seismic zones of northern Algeria, the accelerograms are scaled from 0.1 to 2.5 in increments of 0.1. The results mainly indicate that private constructions built after the Boumerdes earthquake in the moderate and high seismic zones with four (04) or more storeys are highly vulnerable.

Key Words
accelerograms; damage state; fragility curves, IDA; intensity measure; seismic vulnerability

Address
Nourredine Belhamdi: Laboratoire de Génie de la Construction et Architecture (LGCA), Faculté de Technologie, Université de Bejaia, 06000 Bejaia, Algeria

Abderrahmane Kibboua: Department of Civil Engineering, National Earthquake Engineering Research Center CGS, 01 Rue Kaddour RAHIM, BP 252, Hussein Dey, Algiers, Algeria

Abdelkader Tahakourt: Laboratoire de Génie de la Construction et Architecture (LGCA), Faculté de Technologie, Université de Bejaia, 06000 Bejaia, Algeria

Abstract
The axial compression behavior of nine self-compacting concrete columns confined with CFRP-PVC spirals was studied. Three parameters of spiral reinforcement spacing, spiral reinforcement diameter and height diameter ratio were studied. The test results show that the CFRP strip and PVC tube are destroyed first, and the spiral reinforcement and longitudinal reinforcement yield. The results show that with the increase of spiral reinforcement spacing, the peak bearing capacity decreases, but the ductility increases; with the increase of spiral reinforcement diameter, the peak bearing capacity increases, but has little effect on ductility, and the specimen with the ratio of height to diameter of 7.5 has the best mechanical properties. According to the reasonable constitutive relation of material, the finite element model of axial compression is established. Based on the verified finite element model, the stress mechanism is revealed. Finally, the composite constraint model and bearing capacity calculation method are proposed.

Key Words
bearing capacity calculation; CFRP-PVC confined concrete; composite restraint; failure mode; spiral reinforcement

Address
Zongping Chen: College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, P.R. China
Key Laboratory of Disaster Prevention and Structure Safety of Chinese Ministry of Education, Guangxi University, Nanning 530004, P.R. China

Ruitian Xu: College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, P.R. China

Abstract
This study proposes an intelligent semi-active isolation system combining a variable-stiffness control device and ground motion characteristic prediction. To determine the optimal control parameter in real-time, a genetic algorithm (GA)-fuzzy control law was developed in this study. Data on various types of ground motions were collected, and the ground motion characteristics were quantified to derive a near-fault (NF) characteristic ratio by employing an on-site earthquake early warning system. On the basis of the peak ground acceleration (PGA) and the derived NF ratio, a fuzzy inference system (FIS) was developed. The control parameters were optimized using a GA. To support continuity under near-fault and far-field ground motions, the optimal control parameter was linked with the predicted PGA and NF ratio through the FIS. The GA-fuzzy law was then compared with other control laws to verify its effectiveness. The results revealed that the GA-fuzzy control law could reliably predict different ground motion characteristics for real-time control because of the high sensitivity of its control parameter to the ground motion characteristics. Even under near-fault and far-field ground motions, the GA-fuzzy control law outperformed the FPEEA control law in terms of controlling the isolation layer displacement and the superstructure acceleration.

Key Words
fuzzy inference system; genetic algorithm; ground motion characteristic; seismic isolation; semi-active control; stiffness-variable

Address
Tzu-Kang Lin: Department of Civil Engineering, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan

Lyan-Ywan Lu: Department of Civil Engineering, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan

Chia-En Hsiao: Department of Civil Engineering, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan

Dong-You Lee: Department of Civil Engineering, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan

Abstract
This paper presents a structural performance assessment of a historical masonry clock tower both using numerical and experimental process. The numerical assessment includes developing of finite element model with considering different types of soil-structure interaction systems, identifying the numerical dynamic characteristics, finite element model updating procedure, nonlinear time-history analysis and evaluation of seismic performance level. The experimental study involves determining experimental dynamic characteristics using operational modal analysis test method. Through the numerical and experimental processes, the current structural behavior of the masonry clock tower was evaluated. The first five experimental natural frequencies were obtained within 1.479-9.991 Hz. Maximum difference between numerical and experimental natural frequencies, obtained as 20.26%, was reduced to 4.90% by means of the use of updating procedure. According to the results of the nonlinear time-history analysis, maximum displacement was calculated as 0.213 m. The maximum and minimum principal stresses were calculated as 0.20 MPa and 1.40 MPa. In terms of displacement control, the clock tower showed only controlled damage level during the applied earthquake record.

Key Words
clock tower; dynamic characteristics; FE model updating; historical masonry structures; operational modal analysis; soil-structure interaction

Address
Murat Günaydin: Karadeniz Technical University, Department of Civil Engineering, Trabzon, Turkey

Esin Ertürk: Karadeniz Technical University, Department of Civil Engineering, Trabzon, Turkey
Yalova University, Department of Civil Engineering, 77200, Yalova, Turkey

Ali Fuat Genç: Karadeniz Technical University, Department of Civil Engineering, Trabzon, Turkey

Fatih Yesevi Okur: Karadeniz Technical University, Department of Civil Engineering, Trabzon, Turkey

Ahmet Can Altunişik: Karadeniz Technical University, Department of Civil Engineering, Trabzon, Turkey

Cengiz Tavşan: Karadeniz Technical University, Department of Civil Engineering, Trabzon, Turkey

Abstract
In recent years, some studies have identified and quantified factors that can increase or decrease the seismic vulnerability of buildings. These modifier factors, related to the building characteristics and condition, are taken into account in the vulnerability assessment, by means of a numerical estimation resulting from the quantification of these modifiers through vulnerability indexes. However, views have differed on the definition and the quantification of modifiers. In this study, modifier parameters and scores of the Risk-UE Level 1 method are adjusted based on the Algerian seismic code recommendations and the reviews proposed in the literature. The adjusted modifiers and scores are applied to reinforced concrete (RC) buildings in Boumerdes city, in order to assess probable seismic damage. Comparison between estimated damage and observed damage caused by the 2003 Boumerdes earthquake is done, with the objective to (i) validate the model involving influence of the modifier parameters on the seismic vulnerability, and (ii) to define the relationship between modifiers and damage. This research may help planners in improving seismic regulations and reducing vulnerability of existing buildings.

Key Words
Boumerdes city; LM1 method; modifier parameters; seismic vulnerability

Address
Amira Oumedour: Laboratory of Solid Mechanics and Systems, University of M'Hamed Bougara, Boumerdes, Algeria
Department of Civil Engineering, M'Hamed Bougara University of Boumerdes , Avenue de l

Abstract
This paper introduces a novel, rigorous, and efficient probabilistic methodology for the performance-based optimal design (PBOD) of semi-active tuned mass damper (SATMD) for seismically excited nonlinear structures. The proposed methodology is consistent with the modern performance-based earthquake engineering framework and aims to design reliable control systems. To this end, an optimization problem has been defined which considers the parameters of control systems as design variables and minimization of the probability of exceeding a targeted structural performance level during the lifetime as an objective function with a constraint on the failure probability of stroke length damage state associated with mass damper mechanism. The effectiveness of the proposed methodology is illustrated through a numerical example of performance analysis of an eight-story nonlinear shear building frame with hysteretic bilinear behavior. The SATMD with variable stiffness and damping have been designed separately with different mass ratios. Their performance has been compared with that of uncontrolled structure and the structure controlled with passive TMD in terms of probabilistic demand curves, response hazard curves, fragility curves, and exceedance probability of performance levels during the lifetime. Numerical results show the effectiveness, simplicity, and reliability of the proposed PBOD method in designing SATMD with variable stiffness and damping for the nonlinear frames where they have reduced the exceedance probability of the structure up to 49% and 44%, respectively.

Key Words
fragility curves; performance-based optimal design (PBOD), response hazard curves; semi-active tuned mass damper (SATMD); stroke length damage state

Address
Mohtasham Mohebbi: Faculty of Engineering, University of Mohaghegh Ardabili, 56199-11367, Ardabil, Iran

Sina Bakhshinezhad: Faculty of Engineering, University of Mohaghegh Ardabili, 56199-11367, Ardabil, Iran


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