Masoud Nekooei

Islamic Azad University Tehran Science and Research Branch | SRBIAU · Department of Civil Engineering

Providing a connection tool between different structures in an offshore complex, flare bridges are one of the most important offshore structures. Early damage identification in these structures is of great importance, as it may prevent casualties as well as financial and environmental losses. Modal strain energy is one of the most promising structu...

Being exposed to huge waves, repetitive wetting and drying as well as vessel collisions, members that are located in the splash zone of offshore platforms are prone to damage and failure. Providing the possibility of identifying and repairing these damages at an early stage, establishing a concise structural health monitoring system for these struc...

Catwalks are one of main components of each offshore complex. Their most important functionality is to provide connection between different parts such as the jackets and flare or between two neighboring jackets. Due to the catastrophic environmental and financial losses as well as the more importantly, loss of lives in case of the failure of an off...

Vertical mass isolation approach is a new technique in which an individual structure is divided into two distinct subsystems and each possesses different characteristics. Such two subsystems–mass and stiff subsystems– are interconnected with passive dampers in vertical layers at the height of the frame. The primary task of such passive devices is t...

The present study is an attempt to investigate structures equipped with friction dampers under the influence of near-field earthquakes based on Stribeck friction behavior of velocity function. At present, the cyclic behavior of friction dampers in structural design engineering software is simple and based on the Coulomb friction force that is indep...

Vertical mass isolation (VMI) method is used for the seismic control of structures. In this method, the entire structure is considered to be a combination of two mass and stiffness subsystems with an isolator layer located in-between. A magnetorheological (MR) damper is used as the isolator layer to control the structure. The semi-active control te...

The use of waste glass in concrete can bring significant economic and environmental benefits due to reduction of landfills and demand for natural aggregates. This paper presents a comprehensive investigation on the feasibility of using high volume of waste glass as fine aggregate in self‐compacting concrete (SCC). A detailed investigation on fresh...

In this article, a novel vibration-based damage detection approach is proposed based on selecting effective cepstral coefficients, consisting of three main stages: (1) signal processing and feature extraction, (2) damage detection by combining effective cepstral coefficients through feature selection methods, and (3) performance evaluation. First,...

This paper presents a novel approach for detecting damage in a cable-stayed bridge based on adaptive signal processing and feature extraction. The Empirical Mode Decomposition (EMD) technique is employed in this research to obtain the Intrinsic Mode Functions (IMFs). Several features in time and frequency domains are extracted from IMFs as damage-s...

Mass isolation of structures is an efficient vibration-control technique for reducing earthquake effects on buildings. This paper introduces a vertical seismic isolated rocking-core system (VSI-RCS) in which a controlled rocking-core is separated from the frame by viscous fuses. The controlled rocking-core provides the self-centring capability whil...

One of the effective parameters in the dynamic behavior of reinforced soil walls is the fundamental vibration frequency. In this paper, analytical expressions for the first three natural frequencies of a geosynthetic reinforced soil wall are obtained in the 3D domain, using plate vibration theory and the energy method. The interaction between reinf...

Dams are rarely built on non-permeable lands, therefore usually reservoir leakage from dam foundations cause major problems for large dams which affect dams performances. One method of controlling the origin of leaks is to use plastic concrete cutoff walls. Bentonite is one of the most important materials used in constructing plastic concrete which...

In this paper, a novel approach is presented to detect damage in a cable-stayed bridge based on feature extraction and selection. In the first part of the paper, several features are used in time domain, frequency domain, and time-frequency domain to detect damage. Next, several spectral parameters are introduced as effective features to reduce fal...

Structural fuses and rocking system are used in order to reduce the building response to earthquakes and damage guidance. In the proposed seesaw motion system, which is similar to the rocking system, the building columns, in top of the foundation, have been removed and a central support and structural fuses are used around the building instead of t...

Considering the high importance of energy-carrying buried pipelines in lifeline network, it is vital to understand this kind of structures against seismic dynamic excitations. In this paper, seismic behavior in some part of a buried pipe with horizontal bend under Bam earthquake record effect (2003, Iran) is studied experimentally and numerically u...

The behavior and response of pipelines subjected to slip fault movement is studied by numerical simulations as well as experimental setup. A finite element modeling is also developed via ABAQUS software. In this study, an artificial accelerogram is applied to the system and matched against the response spectrum according to the standard No. 2800 (I...

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...

An experimental program was arranged to investigate the relationship between shear deformation and pinching in lightweightaggregate reinforced concrete beams under cyclic loading. Lightweight-aggregate reinforced concrete beams and their connection to column were selected for the purpose of this study and their flexural and shear behaviors experime...

Skewed bridges due to the specific dynamic characteristics have shown vulnerability in recent strong earthquakes. In this study, an active control strategy is employed to optimize the seismic performance of a typical model of such structures. As the control algorithm, the pole placement method has been used, of which the key factor is selection of...

This paper presents the probabilistic generation of collapse fragility curves for evaluating the performance of 3D, reinforced concrete (RC) moment-resisting building models, considering soil-structure interaction (SSI) by concentration on seismic uncertainties. It considers collapse as the loss of lateral load-resisting capacity of the building st...

Most of the proposed methods for obtaining the free vibration natural frequency of the retaining wall assume the behavior of the wall in the two-dimensional domain, and they are not able to express the three-dimensional behavior of these structures in a satisfying manner. Moreover, the effect of damping has not yet been considered in analytical stu...

از آنجایی که سدها به ندرت بر روي زمینهاي ناتراوا ساخته می شوند معمولاً فرار آب مخزن از پی سد یکی از مسائل سدهاي بزرگ به شمار می آید که برکارایی سد و ایمنی تأسیسات دائمی سد تأثیرگذار است. یکی از روشهایی که براي کنترل این تراوشات به کارگرفته میشود استفاده از دیوار آببند بتنپلاستیک است. بتنپلاستیک به دلیل داشتن خاصیت نفوذپذیري پایین، رفتارپلاستیکی و خ...

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...

The behavior of moment resistant steel structures depends on both the beam-column connections and columns foundations connections. Obviously, if the connections can meet the adequate ductility and resistance against lateral loads, the seismic capacity of these structures will be linked practically to the performance of these connections. The shape...

Most of the proposed methods for obtaining the free vibration natural frequency of the retaining wall have been presented, assuming the behavior of the wall in two-dimensional domain, and they are not able to express the three-dimensional behavior of these structures in a satisfying manner. In this paper, the plate theory is employed to analyze the...

This article is all about using the MR damper with an external lever system for mitigation torsional and transitional lateral displacements by using of PID control algorithm. The torsional modes are so destructive and can be varied during an earthquake therefore, using a semi-active control system mostly recommended for them. In this paper the corn...

Stress reduction factor, λ, is a dimensionless coefficient in two-dimensional (2D) analysis based on convergence confinement method (CCM) of tunnel which represents stress relaxation in the tunnel walls at different excavation steps. The aim of this paper is to look into the influencing factors on parameter λ around the tunnel walls using finite di...

Connections in MRFs are the most important members and seismic behaviour is affected by function of beam column connections as well as column foundation connections. If the connections are able to provide the required ductility and efficiency against the seismic excitation, the seismic capacity of the MRF performed by these connections will be affe...

In vertical seismic isolation (VSI), a building is partitioned intentionally by vertical layers into two dynamically different substructures for seismic response reduction. Initially, a 1-story frame was partitioned into two substructures, interconnected by viscous and visco-elastic links, and seismic responses of the original and the vertically is...

The variability in engineering design decisions results in the building models with considerably different deterioration properties. So, this paper investigates the effect of different deteriorating hysteretic model parameters on the response of asymmetric buildings. The example buildings are 5-story symmetric and asymmetric buildings. The maximum...

In an actual design, none of the structures with shear behaviors will be designed for torsional moments. Any failure or damages to roofs, infills, shear walls, and braces caused by an earthquake, will inevitably result in relocation of center of mass and rigidity of the structure. With these changes, the dynamic characteristics of structure could b...

Steel structures often need strengthening due to increased life loads, or repair due to corrosion or fatigue cracking. Multiple studies have been performed concerning the structural steel beams, while few have been conducted on columns. The stability of columns is very important in steel structures. It is one of the main factors in buckling instabi...

Multi Span Simply Supported Bridges (MSSS) are categorized among the most vulnerable bridge classes and their vulnerability increases when different sources of irregularities such as skewness as well as columns height differences are included. Different sources of irregularities make the irregular bridge more complicated in case of dynamic response...

Background/Objectives: Investigation the behavior of lightweight aggregate concrete beams and connection under cyclic loading and compare it with the behavior of concrete beam with normal weight. Methods/Statistical Analysis: This study is focused on the experimental investigation of the behavior of the beams constructed of scoria lightweight aggre...

The need for strengthening and retrofitting is well known and extensive research is progressing in this field. The reasons for strengthening and retrofitting are numerous: increased loads, changes in use, deterioration, and so on. In recent years, the use of carbon fiber reinforced polymer (CFRP) for strengthening has shown to be a competitive meth...

This article is all about the combination of an intelligent system such as a photoelectric sensor with MR damper that would be able to control the shear and torsional displacements of buildings. This paper will show how the appropriate algorithm is for current injection into MR Damper in order to control the lateral displacement of structure when t...

This study primarily investigates if the building asymmetry changes the variance of collapse capacity. The example models are five-story reinforced concrete buildings. The variance of collapse capacity is evaluated by first-order-second-moment method. There is a difference between the results of symmetric and asymmetric building models, independent...

SUMMARY A variety of new approaches in seismic design of structures are based on improving the flexibility and energy dissipation potentials of the system. In these approaches the existence of large energy dissipaters in the system and the structural mechanism that supports the reaction forces of these devices make the current single degree of free...

Mass isolation of structures is one of the new techniques in seismic design of structures that focuses on the mass of the structure as the main target for seismic isolation and reducing earthquake effects on buildings. In this study, the seismic behaviour of vertical mass isolated structures against the earthquake was studied. The analytical model...

In this paper, the seismic behaviour of vertical mass isolated structures against the earthquake is studied. These structures are assumed to be consisted of two subsystems. Mass subsystem possesses low lateral stiffness but carries the major part of mass of the system. Stiffness subsystem, however, controls the deformation of the mass subsystem and...