Abdolreza S. Moghadam

International Institute of Earthquake Engineering and Seismology | iiees · Structural Engineering Research Center

This paper proposes a novel Dual-Linked Column Frame (DLCF) system with the rocking motion of moment frame column bases. The novel Dual-Linked Column Frame with Rocking motion (DLCFR) increases the seismic capacity of the moment frame and the linked beam as a structural fuse to dissipate energy. Rocking column bases can dissipate energy through fus...

A controlled rocking concentrically steel braced frame (CR-CSBF) is introduced as an alternative to conventional methods to prevent major structural damage during large earthquakes. It is equipped with elastic post-tensioned (PT) cables and replaceable devices or fuses to provide overturning resistance and dissipate energy, respectively. Although C...

This paper investigates the seismic performance of one-story one-bay steel moment-resisting frames with flexible column bases from theoretical and numerical perspectives. It is shown that increasing the base flexibility decreased the column top moment for medium to long period elastic structures, thereby reducing the possibility of a soft-story mec...

Earthquake damage in concretre structures has led to the development of new methods for the design and construction of earhquake resistant concrete structures. But recent earthquakes have shown that concrete structures are damaged by earthquakes, making them very difficult and even impossible to repair . For this reason, after relatively severe ear...

Structural health monitoring and natural control (SHMC) for post‐earthquake realignment and repairs (PERR) are one of the most challenging issues facing earthquake engineers worldwide. Currently, neither SHMC nor PERR are parts of contemporary curricula and codes of practice. SHMC aims to help achieve a viable degree of structural sustainability (S...

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While plan-asymmetric structures have more potential for torsional effects and diaphragm flexibility during seismic response, they had received less attention from this viewpoint in previous studies. In fact, due to the complex torsional-flexibility interaction of asymmetric structures with flexible diaphragms when subjected to seismic responses, e...

Generally, in the analysis and design of buildings, the foundation is assumed to be rigid and the effect that soil subsidence under the foundation and the flexibility of the foundation may have on the response of the structure is not considered. If the interaction between the structure, the foundation and its supporting soil environment significant...

This study describes an experimental program designed to investigate the influence of the presence and orientation of hollow-core wall panels as well as beam to column connection rigidity on the seismic performance of steel frames infilled with hollow-core wall units. For this purpose, four half-scale, single-story, and single-bay specimens, includ...

The capability of reduced beam sections (RBS) to improve the seismic behavior of rigid connections leads to their notable application in steel moment-resisting frames. However, they may encounter shortcomings such as local buckling and lateral-torsional buckling. To resolve such problems, the idea of utilizing perforated beam flanges instead of cut...

The vulnerability of industrial plants to natural hazards has made world worries because of countries general disability about the prediction of the level of effects and preparedness for the consequences of these types of events. For this purpose, seismic assessment of plant equipment is a strategic issue. One of the most equipment that is used in...

This paper evaluates the accuracy of bidirectional energy-based pushover (BEP) procedure in predicting approximate incremental dynamic analysis (IDA) results for medium- and high-rise structures. BEP provides approximate IDA curves under the simultaneous effect of the two horizontal components of ground motions and is applicable to both symmetric-...

The stiffness of many lateral force resisting elements depends on their strength. The early studies indicated a relatively better performance of the strength symmetric design model (zero-strength eccentric model) compared to other design models. However, further investigations claimed that the balance design model could endow the best seismic perfo...

With regard to the effects of self-centering structural performance in reducing damages in the event of an earthquake, in this study an attempt is made at developing a repairability index for post-tensioned self-centering steel moment connections. Based on the 18 structural models studied, a building in which the maximum connection rotation does no...

Recently developed steel self-centering moment-resisting frames (SC-MRFs) have been analytically and experimentally validated as having the potential to eliminate structural damage under a design basis earthquake and restore their original vertical position following a major earthquake. In this study, the Repairability Index of Post-tensioned Self-...

Recently developed steel self-centring moment-resisting frames have been analytically and experimentally validated as having the potential to eliminate structural damage under a design basis earthquake and restore their original vertical position following a major earthquake. In this study, the repairability index of post-tensioned self-centring fr...

Examination of the behavior of structures in past earthquakes shows that asymmetric torsion has been one of the causes of severe vulnerabilities Considering the advantages of modern seismic design methods in which energy dissipation additives such as dampers are used to control the responses in an earthquake, it is possible to control the seismic t...

Earthquake damage in concrete structures has led to the development of new methods for the design and construction of earthquake resistant concrete structures. But recent earthquake have shown that concrete buildings are damaged by earthquakes that are very difficult and even impossible too repair. Therefore in this study a new system has been deve...

Earthquake damage in concrete structures has led to the development of new methods for the design and construction of earthquake resistant concrete structures. But recent earthquake have shown that concrete buildings are damaged by earthquakes that are very difficult and even impossible too repair. Therefore in this study a new system has been deve...

Self-centering controlled rocking steel braced-frame (SC-CR-SBF) is proposed as an earthquake-resistant system with low damage. Pre-stressed vertical strands provide a self-centering mechanism in the system and energy absorbing fuses restrict maximum displacement. Presence of asymmetry in structures can highlight the advantages of employing this st...

Recent studies show that the evaluation of structures in the energy domain has attracted some researchers’ attention in the field of progressive collapse. Column buckling and failure energy were introduced as the energy-based criteria and can be obtained from the single-column displacement controlled analysis for progressive collapse assessment of...

Conventional earthquake-resistant systems, often experience inelastic behavior in a part of the structure during a large earthquake and eventually causing residual deformation and damage to the structure. Repairing these damages are unaffordable and often leads to structure destruction. Therefore, the use of structures with the ability to focus dam...

Controlled rocking steel cores (CRSCs) with reliable self-centering capability have been known as a low-damage seismic force-resisting system. The flag-shaped hysteresis response of CRSCs can be provided using unbonded post-tensioning tendons and replaceable energy dissipation devices. This paper examines the seismic performance of CRSCs subjected...

Assuming that damages to buildings in earthquake are repairable, retrofitting them is not always economically justified. As an alternative solution, buildings can be designed such that damages are limited to only easily repairable elements. One of the structural systems that provide this possibility is the post-tensioned self-centering moment resis...

Bidirectional energy-based pushover (BEP) procedure is expanded in this paper to predict approximate incremental dynamic analysis (IDA) results of medium- and high-rise structures. BEP is a unique approach in the sense that it provides approximate IDA curves under the simultaneous effect of two horizontal components of ground motions and is applica...

Engineers may make various decisions based on the engineering judgment while they design a building, or may choose different methods for modeling the structural components, especially the way by which the deteriorating behavior of elements should be incorporated. Such decisions cause the engineering demand parameters (EDPs) to depend on the deterio...

Fully rigid floor diaphragm is one of the main assumptions that are widely used in common practices due to its simple application. However, determining the exact degree of diaphragms flexibility cannot be easily accomplished without finite element modeling, which is an expensive and time-consuming procedure. Therefore, it is always possible that ap...

Linked Column Frame (LCF) is a seismic load resisting system with ductile behavior. In this system, the link beam, operating as a shear fuse, reduces or eliminates damages to other components of the structure under various hazard levels. In this study, by combining the rocking motion and changes in the linked column pattern, an innovative seismic-r...

Recent studies indicate that the column buckling energy as a necessary but not a sufficient criterion, and the column failure energy as a sufficient criterion can be obtained from the single-column displacement controlled analysis, and considered as energy-based criteria in progressive collapse considerations. The structural performance following t...

Controlled rocking concentrically steel braced frame (CR-CSBF) is an earthquake-resisting system that is effectively capable of reducing structural damage after earthquakes and causes resilience in the structure. Post-tensioning (PT) strands and fuse members are two important elements in CR-CBSFs to provide frame self-centering and energy dissipati...

The specific operating conditions in concrete box-type (tunnel-form) buildings would lead to the concentration of walls in the interior parts of the plan and lack of structural walls in the perimeter of the plan. In this situation, due to the considerable reduction in torsional stiffness, usually torsional vibration modes prevail over translational...

Seismic dynamic analysis of earth dams is usually performed with two-dimensional cross sections. Since in some situations, the three-dimensional performance of the dam and its supports such as asymmetric shape of the valley can be very influential in the results, thus in this paper the seismic dynamic behavior of earth dam with symmetrical and asym...

The reduced beam section (RBS) connections are used to improve the seismic behavior of rigid connections. The brittle failure and lateral-torsional buckling are the drawbacks of these connections. Drilled flange connections (DFC) are one of the novel configurations of RBS connections. This form of the reduction in beam section can reduce the probab...

Traditional earthquake-resistant systems are dependent on the inelastic response of the building members. These systems experience significant residual displacements after major earthquakes due to seismic energy distribution all over the building and make their repair uneconomical. Self-Centering systems in steel frame buildings omit residual displ...

Research bulletin of Seismology and Earthquake Engineering, Vol.20, No 4, Winter 2018. http://www.rbsee.ir/index.php/rbsee/article/view/223/186

To overcome complexities and shortcomings of previous studies, a new method is proposed to derive an equivalent linear model for predicting seismic hysteretic energy demand of bilinear single degree of freedom (SDOF) models. A new displacement spectrum is defined, which represents hysteretic energy. It is found that by increasing initial period and...

The seismic design of the structures is carried out by technical regulations and codes in free-field conditions (regardless of underground cavities). While with the availability of tunnels and the complex interaction between the tunnel and the aboveground structures, may be contemplated wrongly, which could be dangerous for over ground buildings an...

The construction and designing technology of earthquake-resistant systems has greatly improved to reduce its detrimental effects on buildings, hospitals, and utilities over the years. Therefore, ground stimuli result from accelerating the structural floors led to alter the lateral location of the building and the potential risk for structural and n...

Damage data after strong earthquakes has had an important application in revising codes and design criteria or changing the practice methods in different regions. The data has also been used for developing seismic fragility curves for different types of structures. A project for damage data collection after earthquakes has been defined recently in...

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Hysteretic energy is defined as energy dissipated through inelastic deformations during a ground motion by the system. It includes frequency content and duration of ground motion as two remarkable parameters, while these characteristics are not seen in displacement spectrum. Since maximum displacement individually cannot be the appropriate criterio...

The seismic performance of elliptic braced moment resisting frame (ELBRF) is assessed here and is found that the structural behavior is improved and is of free of architectural space. The demand for seismic performance of ELBRF is estimated through conventional pushover methods of 3, 5, 7, and 10-story ELBRF frames and they are compared with specia...

Performance‐based seismic design, as an alternative to conventional methods of approach, has served engineers and the public rather well during the last two decades. Neither approach guaranties catastrophic collapse prevention nor post‐earthquake realignment and repairs (PERR) due to major seismic events. As a result, most code‐compliant buildings...

Today, the evaluation of the performance of structures against earthquakes has attracted the attention of many researchers around the world. One of the key and precise tools in determining the assessment of the seismic vulnerability of the structures is fragility functions that express the damage exceedance probability of a structure from a specifi...

The effects of diaphragm flexibility on seismic response of asymmetric-plan buildings are investigated in this paper. The results show that the diaphragm flexibility could induce different effects depending on the asymmetric system characteristics, selected element, level of structure yield, and degree of diaphragm flexibility. When the structure b...

This paper proposes a methodology for developing earthquake‐resilient structures (ERSs). This is achieved by following principles of full cycle performance control and embracing a holistic approach to design led analysis (DLA) of ERS. Collapse prevention (CP) and postearthquake realignment and repairs (PERRs) are the basic traits of ERS. Despite th...

Modern rocking and stepping cores have been known as the efficient self‐centering earthquake‐resisting systems (SC‐ERSs). The current article proposes an approximate equivalent linear (EL) model for rapid estimation of the SC‐ERS displacement. An equivalent damping ratio and effective stiffness are formulated for flag‐shaped hysteresis of a fully S...

This paper presents seismic behavior of several buildings with low torsional stiffness. The performance criterion is story drift ratio, as story drift ratio is an appropriate damage index for structural and non-structural elements comparably. Therefore, the safety of structure is defined by mentioned criterion. This study illustrates that the propo...

Unlike conventional seismic resisting systems, rocking core-moment frame (RCMF) combinations as low-damage assemblies are being developed to mitigate, or even eliminate structural damage and residual deformations following a severe earthquake. Despite extensive studies on the performance of specific rocking cores, dynamic characteristics and streng...

In masonry buildings, walls are the main structural members that deal with lateral forces. The important point in seismic retrofitting projects is identifythe most effective method of improving in various levels of displacement. Therefore, in this study based on laboratory results, 12 reinforced and unreinforced walls are subjected to cyclic load,...

Controlled-rocking braced frames are capable of reducing the drawbacks of conventional frames against seismic loading. This paper examines the effects of soil-foundation modeling on the seismic responses of low-rise controlled-rocking braced frames. For this purpose, dynamic analyses are performed on rocking braced frames and similar conventional f...

The results of the eigenvalue analyses of many tunnel form concrete buildings represent primacy of torsional modes to transitional modes leading to torsionally flexible behavior of those buildings. Considering the regularity provisions for tunnel form buildings in plan, it appears that probable eccentricity of mass and stiffness caused by asymmetri...

This paper presents evaluation of reinforced concrete structures subjected to multiple low intensity earthquakes (earthquakes in the range of 3≤𝑀_𝑤≤5) effects in their lifetime. This study focused on the effect of accumulated damage of repeating low intensity earthquakes on moment resisting reinforced concrete structures, using OpenSees software.

The ductility capacity of bridge piers is estimated uniaxially by moment-curvature analysis, regardless of the amount of flexural demand on the perpendicular axis of the section. In this study, by applying a numerical fiber-based model, the ductility capacity of reinforced concrete (RC) piers subjected to biaxial monotonic loadings is investigated....

Decision making for selecting an appropriate alternative among nominated alternatives is still a problem among retrofit designers. It is clear that selected alternative should comply the current codes in terms of structural criteria, but the other criteria may not be considered. The main goal of this study is to introduce a suitable method for maki...

Rocking core-moment frame (RCMF) combinations are structural assemblies that are capable of collapse prevention, recentering, avoiding soft story failure, and large residual deformation. Although several such systems have been proposed, few studies have quantified RCMFs behavior under lateral loadings. This paper proposes closed-form solutions for...

With respect to Iran seismicity and probability of seismic damages especially for petroleum facilities and plants, in recent years, Iranian Ministry of Petroleum (MOP) Department of Engineering has decided to establish a technical code for seismic design of petrochemical plants, refineries, pipelines, etc. This code (available on "http://det-mop.i...

Common earthquake-resistant systems often experience non-elastic behavior during a large earthquake throughout the structure, which ultimately results in residual deformation and distributed failure in the structure. Therefore, after an earthquake, these buildings are damaged and destroyed. In order to reuse the structure, you need to spend a lot o...

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Rocking core-moment frame (RCMF) combinations are structural assemblies that are capable of collapse prevention, recentering, avoiding soft story failure, and large residual deformation. Although several such systems have been proposed, few studies have quantified RCMFs behavior under lateral loadings. This paper proposes closed-form solutions for...

Common earthquake-resistant systems often experience non-elastic behavior during a large earthquake throughout the structure, which ultimately results in residual deformation and distributed failure in the structure. Therefore, after an earthquake, these buildings are damaged and destroyed. In order to reuse the structure, you need to spend a lot o...

Incremental dynamic analysis (IDA) is recognized as a valuable method for assessing the performance of structures under earthquake excitation. Since IDA is computationally intensive, a number of previous studies have attempted to approximate IDA curves using pushover analysis. As a requirement for assessments of asymmetric buildings, IDA under two-...

In conventional seismic design codes of building structures severe structural damage due to large earthquakes is accepted, provided that the structure does not collapse, and life safety of the residents is guaranteed. The extent of this allowed damage can be so high that after earthquake, demolition and reconstruction of the building becomes inevit...

In-plane seismic behaviour of concrete sandwich panel-infilled steel frame (CSP-ISF) was experimentally and numerically investigated. Four large-scale, single bay and single story steel frame specimens were tested under reversed cyclic lateral loading. Three infilled frames with different aspect ratios along with one bare frame were considered. It...

The seismic behavior of asymmetric structures with a flexible diaphragm was studied by conducting inelastic dynamic time-history analyses. Asymmetric structures with different configurations of mass, stiffness, and strength centers, in combination with a wide range of diaphragm flexibility, were evaluated. The behavior of structures was studied by...

Design codes utilize the ductility and over-strength of the structural components to achieve target performances such as life safety and collapse prevention. Design with this attitude leads to significant damage following a severe earthquake event. This paper presents a design algorithm for self-centering steel braced frame. This system consists of...

The paper introduces a number of new analytic techniques and practical technologies that lead to the development of an efficient earthquake resistant system. The proposed structural system consists of a grade beam supported moment frame connected to a rigid rocking core through story level rigid links. The new system tends to bend and tilt as an up...