Mussa Mahmoudi

• PhD
• Professor at Shahid Rajaee Teacher Training University

The aim of this study was to examine how the tensile strength of glass fibre reinforced polymer stirrups is affected by different types of solutions, including alkaline, seawater, tap water, and acidic solutions. The study involved the production and testing of 260 stirrups in two different shapes (L and U) with diameters of 6 and 8 mm. The stirrup...

GFRP stirrups are a promising alternative to conventional steel stirrups due to their non-corrosive nature. However, their performance under cyclic exposure to wet-dry and freeze-thaw conditions in seawater needs to be evaluated to ensure their long-term durability and sustainability. This study investigates the tensile strength of glass fibre rein...

The train-induced vibrations on the buildings nearby the railway lines was a serious challenge for the citizens. Therefore, it was necessary to provide a simple model to predict vibrations in the buildings. In response to this need, a numerical model based on the results of modal analysis of buildings was developed. The modal parameters of the buil...

Despite having appropriate architectural performance, high strength, and acceptable stiffness, steel Y-shaped braces still demonstrate insufficient ductility. Moreover, the risk of buckling, especially in some of the longest members, can be counted as another deficiency in such systems. One of the methods to alleviate these demerits is employing da...

This paper presents an efficient Proper Orthogonal Decomposition (POD) based methodology for structural finite element model updating problem. In the proposed methodology, the vibrational responses of the system are projected into proper modal coordinates and then the Power Spectrum Density (PSD) Functions of the projected data are used to establis...

Researchers in the field of earthquake engineering are always looking for new ways to improve the seismic behavior of structures. The buckling-restrained brace (BRB) is one of these exciting innovations that are employed to increase the ductility capacity of traditional steel braced frames. Understanding the nonlinear response of these novel system...

The method of Proper Orthogonal Decomposition (POD) is one of the popular techniques used in structural dynamics. Unlike Linear Natural Modes (LNMs), Proper Orthogonal Modes (POMs) derived from the POD method, depend on the excitation loads in addition to the mass and stiffness of the dynamical system. According to the various researches in establi...

Dynamic properties of structures, such as natural frequency, mode shapes, and damping ratios, play a decisive role in the structural behavior against dynamic loads such as earthquakes. One of the utilizations of these properties is the determination of the earthquake forces imposed on structures based on the design spectra. Other applications of th...

Steel braced frames are structures installed in order to resist lateral forces of the earthquake in the construction. Despite the high stiffness and strength of these lateral systems, most of them do not have enough ductility and architectural performance. Y-shaped bracings can be used to deal with architectural issues, although these braces also d...

The foundation of buildings commonly assumed to be fixed in practical seismic response analysis. However, in severe earthquake loadings, the uplift phenomenon would be occurred due to the lack of tensile strength in the subsoil. This research aims to investigate this nonlinear phenomenon to obtain the actual behavior of diagonally braced steel fram...

Dynamic characteristics of the structures such as natural frequencies, mode shapes and damping, are inherent parameters of structures which change as a result of local damages. Damage detection using mode shape curvature difference method is too sensitive to the presence of noise. This paper introduces a new method for damage detection in the conne...

The selection of a suitable numerical method to evaluate the dynamic behavior of structures, especially in nonlinear cases, is an important task in practice. Accordingly, the purpose of this study is to demonstrate the numerical features of a new single-step type of the Modified Energy Method (MEM) to compute the dynamic response of structural syst...

The use of slip-critical bolted connections is strongly emphasized for steel structures located in seismic zones by building codes. Obviously, the type of contact surface has a significant effect on the slip resistance of such connections. The purpose of this research is to experimentally and numerically evaluate the effect of the type of plate con...

In the conventional dynamic and static analysis of bridges, changes in seismic waves along the propagation path under the bridge structure are not considered, and it is assumed that the waves received at different points of the bridge supports are the same and they are simultaneously applied to the piers of bridges. Such an assumption requires that...

Recently, various methods have been developed for remote measurement. The most usage of photogrammetry method is the ability to achieve the whole structure and its efficiency for working in test environments, especially where the use of other measurement methods is not accessible. Although, researchers have utilized this method to measure the vibra...

Pipelines as lifeline play a key role in water, gas, and oil delivery. One of the effective factors in the design of buried pipes is fault existence on its path. One of the other effective factors in the pipeline design is the propagation of earthquake waves along it. Wave propagation means that the different parts of the pipes are vibrating with d...

The aim of this study was assessing the seismic performance of three types of mid-span connections in the cross bracing systems including: the mid-span connection with cover plates, the flanged connections and the braced ductile shear panel (BDSP). For this purpose, the linear buckling and post-buckling behavior of the cross braces with the aforeme...

In this paper, an efficient computational solution technique based on the energy balance equations is presented for the dynamic analysis of shear-frames, as an example of a multi-degree-of-freedom system. After deriving the dynamic energy balance equations for these systems, a new mathematical solution technique which is called Elimination of Disco...

Structural elements exhibit cyclic behavior or hysteresis under seismic loads; therefore, the analysis of this type of response is of great importance in Earthquake Engineering. On the other hand, due to the complexity of this nonlinear behavior and the absence of an explicit function to express the restoring-force regarding deformation, the modeli...

Buildings in seismic regions are prone to severe damage due to large deformations and low capacity to absorb energy. X-bracing is effectively employed in maintaining the structure stability when earthquakes occur or extreme lateral loads act on the structure. The widespread use of X-bracing systems in steel structures reveals the importance of unde...

The utilization of smart materials in construction, to improve the seismic response of structures is one of the most interesting topics in earthquake engineering. Accordingly, this study aims to investigate the use of shape memory alloy (SMA) bars within X-knee-braced frames (X-KBFs). To fulfill the objectives of this research, three 3-, 5-, and 7-...

Concentrically braced steel frames should be capable of bearing considerable amounts of lateral force. The connection of these frames to beams and columns plays an important role in this respect. This connection is designed to either prevent end-connection problems caused by free buckling of a member or reinforce the gusset plate to reduce damages...

The braced frame is used in steel structures to confront lateral loads. In Iran, braced frames, especially concentrically braced frames are more commonly used due to their high levels of rigidity and ease and speed of construction. The bracing member of this system bears considerable amounts of load, and thus it needs to be properly connected to th...

In this research, a new numerical method is presented to evaluate the linear and especially the nonlinear dynamic response of single degree of freedom systems. This technique is based on the simultaneous usage of energy and force equilibrium equations which is called the Modified Energy Method. At first, a simple linear system is selected to illust...

The seismic behavior of skewed bridges compared to straight bridges is not well recognized and need more study to investigate its unique behavior under seismic forces. Much more damage have seen from skewed bridges particularly when its deck rotates in the earthquake. Many causes are involved in this behavior such as columns and piers nonlinear def...

Response modification factor (R factor) is one of the seismic design parameters to be considered in evaluating the performance of buildings during strong motions. This paper has tried to evaluate the response modification factor of concrete coupled shear wall structures with various length/depth ratios of spandrel beams. The effect of diagonal rein...

Knee braced frames (KBF) include a diagonal member which provides major lateral stiffness through connecting to the skew knee member. This skew knee member, through its connection to the beam-column and yielding during severe earthquakes as well as energy dissipations, provides the required ductility, deforming in elastically as a mechanical fuse t...

During recent years, the use of fiber-reinforced polymers (FRP) as a desirable alternative for improving the behavior of lateral resisting system are known. There are various factors influencing the quality of such kind of rehabilitation. This study aims to investigate the influence of geometric characteristics and arrangement of FRP layers on reha...

The seismic behavior of skewed bridges has not been well studied compared to straight bridges. Skewed bridges have shown extensive damage, especially due to deck rotation. Many causes are involved in this behavior such as columns and piers nonlinear deformation patterns. The columns material i.e. (concrete or steel) shall influence the pattern of t...

The current building codes provide limited prescriptive guidance on design for protection of buildings due to progressive collapse. Progressive collapse is a situation in which a localized failure in a structure, caused by an abnormal load, such as explosions or other happenings. Three procedures, often employed for determination of the structural...

Abstract Shape memory alloys (SMA) are novel materials that have high elastic strain, so they can be used as materials to improve the seismic performance of structures. The purpose of this paper is to compare seismic behavior of ordinary X-braced frames (XO), with SMA X-braced one, called (XS). As the current paper takes into account the effect of...

Response modification factor is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake. Relying on this, many seismic design codes led to reduce loads. The present paper tries to evaluate the response modification factors of buckling restrained braced frames (BRBFs) utilized for rehabi...

According to seismic design codes, nonlinear performance of structures is considered during strong earthquakes. Seismic design provisions estimate the maximum roof and story drifts occurring during major earthquakes by amplifying the drifts computed from elastic analysis at the prescribed seismic force level with a displacement amplification factor...

The knee bracing steel frame (KBF) is a new type of energy dissipating frame which enjoys exceptional ductility and lateral stiffness. Rather than the beam-column joint, one end of the diagonal brace in KBF is attached to the knee element. Indeed, the knee element as a hysteretic damper is designed and detailed to behave like a structural fuse by s...

In performance based design, the hazard levels and relevant acceptable damages are clearly specified. Structural and non-structural performances are controlled by limiting stiffness, strength and members ductility characteristics. Using displacement amplification factors (Cd) and force reduction factors (R) related to hazard levels, this paper pres...

Yielding elements (YE) are among those devices that not only help control structural damages, but make better seismic behavior by concentrating the frames in some removable part of the structures. YE are located at the intersection of Concentric Braced Frame (CBF) in a rectangular shape. In this paper, Seismic behavior of the frames with YE will be...

Inelastic deformation of structural components is generally acceptable in seismic design. In such behavior, the strength of structures increases while plastic hinges are formed in members frequently. The strength revealed during the formation of plastic hinges is called "overstrength".Overstrength is one of the important parameters in the seismic d...

Response modification factor is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake. Relying on this, many seismic design codes led to reduce loads. The present paper tries to evaluate the response modification factors of conventional concentric braced frames (CBFs) as well as buckl...

For Seismic design, it is important to estimate, maximum lateral displacement (inelastic displacement) of the structures due to sever earthquakes for several reasons. Seismic design provisions estimate the maximum roof and storey drifts occurring in major earthquakes by amplifying the drifts of the structures obtained by elastic analysis subjected...