Reza Rahgozar | Shahid Bahonar University of Kerman (original) (raw)
Papers by Reza Rahgozar
Structures, Apr 1, 2024
This paper presents the simultaneous geometrical and material optimization of functionally graded... more This paper presents the simultaneous geometrical and material optimization of functionally graded doubly-curved shells under static load and free vibration. The weak form of governing equations is derived from third-order shear and normal deformation theory. Bending and free vibration analyses were conducted using the finite element method. The functionally graded material (FGM) is composed of metal and ceramic, and Voigt’s rule of mixtures is applied to capture the characteristics of FGMs throughout the shell thickness direction. In this regard, two multi-objective optimization algorithms (i.e., multi-objective particle swarm optimization and multi-objective cuckoo search optimization algorithms are employed. The objective functions combine minimizing the maximum normalized displacement and mass and maximizing the first dimensionless frequency. The results show that where minimizing the mass of the FG shell structure was considered an objective function, the value of the power index is equal to zero for almost all studied cases.
Journal of Structural and Construction Engineering, Jun 1, 2016
Civil engineering infrastructures journal, Dec 1, 2010
Civil Engineering Journal, Nov 1, 2020
American Journal of Applied Sciences, Apr 1, 2008
International Journal of Engineering, Apr 1, 2012
International journal of engineering. Transactions B: Applications, Nov 1, 2017
2nd international conference on concrete repair, rehabilitation and retrofitting, ICCRRR-2, Nov 24, 2009
Mechanics of Advanced Materials and Structures, 2021
The current literature deals with the multi-objective optimal material distribution of porous fun... more The current literature deals with the multi-objective optimal material distribution of porous functionally graded plates subjected to free vibration in the framework of Carrera Unified Formulation ...
Sustainability, 2004
The free vibration of Timoshenko beams with varying cross-section is reduced to an analytical sol... more The free vibration of Timoshenko beams with varying cross-section is reduced to an analytical solvable standard differential equation. This equation form depends on the specific moment of inertia, cross-section area and mass variation. The more accurate mode shapes and natural frequencies can be obtained by combining the effects of shear and flexural deformation. In this paper the main differential equation of vibration which involves flexural and shear effects (Timoshenko beam without rotary inertia effect) is obtained. The general solution of the main vibration equation has been derived by selecting suitable expressions such as power and exponential functions for the stiffness and mass distribution. Tall structures can be treated as cantilever beams with variable cross-section for their free vibrational analysis. The natural frequencies and mode shapes of tall buildings can be obtained by applying the proposed general solution of Timoshenko beams with varying cross-section. The ca...
Light weight construction is one of topics in civil engineering, the topic of reducing weight of ... more Light weight construction is one of topics in civil engineering, the topic of reducing weight of structure achieves by use of new technique stuction and optimization of procedure construction. Consideration to wide use of concrete and enviromental pollution to the reason of using cement, investigators are trying to replacement of a part of cement by natural and artifitial pozzolan and nano particle and etc. In this study natural pozzolan zeolite as replacement admixture with different percents 0, 5, 10, 15, 20 investigated and longterm and short term effects on the compression and tensile strenght on half light weight concrete at the age 3, 56, 90 days were studied and compared with control specimen. Result shows that 5% and 10% replacement of zeolite improve compression strength at the age of 3, 90 days, and for age of 56 days most improvement is related to 15% replacement by zeolite.
2nd International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR-2, 24-26 November 2008, Cape Town, South Africa, 2008
American Journal of Applied Sciences, 2008
American Journal of Applied Sciences, 2007
Carbon fiber reinforced polymer (CFRP) has been widely used to strengthen steel members in bendin... more Carbon fiber reinforced polymer (CFRP) has been widely used to strengthen steel members in bending. Few research studies have been carried out on strengthening steel members under axial load strengthening by CFRP. The purpose of this study is to evaluate the compressive load capacity of Square Hollow Section (SHS) steel short and slender columns strengthened using CFRP. The numerical analyses using Finite Element Method (FEM) obtained from ANSYS Software were utilized. The results have been verified by experimental analyses. The results showed that CFRP wraps are capable of increasing the compressive load capacity of SHS steel short and slender columns appropriately. In addition when coverage percent CFRP layers was less 100%, CFRP more increased the compressive load capacity of SHS steel slender columns. The numbers of CFRP layers were effective in the compressive load bearing capacity of SHS steel short and slender columns.
Iran University of Science & Technology, 2020
The utilization of passive energy dissipation systems has been created a revolution in the struct... more The utilization of passive energy dissipation systems has been created a revolution in the structural engineering industry due to their advantages. Fluid Viscous Damper (FVD) is one of these control systems. It has been used in many different industries, such as the army, aerospace, bridge, and building structures. One of the essential questions about this system is how it can combine with the bracing system to enhance its abilities. In this paper, a comparison between the responses of a twelve-story steel building retrofitted by four layouts of bracings systems (i.e., chevron, diagonal, toggle, and X-brace) is studied. These bracing systems are equipped by FVD to find the optimum layout for these systems. Buildings are modeled nonlinearity and excited by an earthquake (Manjil earthquake). For this purpose, the Fast Nonlinear Analysis (FNA) is performed using the SAP2000 software. The results show that FVD alters some of the structural behaviors such as inter-story drift when combin...
Journal of Constructional Steel Research, 2008
Mechanics of Advanced Materials and Structures
This paper investigates the bending and vibration characteristics of metallic and functionally gr... more This paper investigates the bending and vibration characteristics of metallic and functionally graded (FG) beam structures. The weak form of governing equations and boundary conditions are derived using Carrera unified formulation (CUF). The isogeometric analysis (IGA) is employed to solve the static and free vibration problems. NURBS basis functions approximate the displacement field unknowns and material gradations in cross-section. In contrast, the axial displacements are evaluated by either NURBS or Lagrange basis functions. In this framework, the equations are extracted in the form of a fundamental nucleus, which allows the study of different beam theories in a constant formulation. Several numerical examples are presented and compared with results available in the literature to address the accuracy and effectiveness of the current approach. It is found that the present results are validated for different aspect ratios, boundary conditions, and material distribution with more accuracy and low computational cost.
The sensitivity of tall buildings subjected to the lateral loads is more than that of the gravity... more The sensitivity of tall buildings subjected to the lateral loads is more than that of the gravity loads. Therefore, the conventional methods are not efficient yet, and new methods such as the use of the belt truss and outrigger systems are proposed by designers to reduce the structural roof displacement, shear lag, overturning moment, and also to increase the lateral resistance of the structures. In the design of tall structures, for economic reasons, it is desirable to reduce the lateral stiffness of the structures along with the height of the structure. In this paper, the framed tube and shear core are modeled using the energy method and the continuous beam model. The optimum location of the belt truss and outrigger system are calculated considering three lateral loading patterns. It is assumed that the lateral stiffness of the framed tube and shear core varies along with the height of the structure. The stiffness of the belt truss and outrigger system is also considered as an equ...
Structures, Apr 1, 2024
This paper presents the simultaneous geometrical and material optimization of functionally graded... more This paper presents the simultaneous geometrical and material optimization of functionally graded doubly-curved shells under static load and free vibration. The weak form of governing equations is derived from third-order shear and normal deformation theory. Bending and free vibration analyses were conducted using the finite element method. The functionally graded material (FGM) is composed of metal and ceramic, and Voigt’s rule of mixtures is applied to capture the characteristics of FGMs throughout the shell thickness direction. In this regard, two multi-objective optimization algorithms (i.e., multi-objective particle swarm optimization and multi-objective cuckoo search optimization algorithms are employed. The objective functions combine minimizing the maximum normalized displacement and mass and maximizing the first dimensionless frequency. The results show that where minimizing the mass of the FG shell structure was considered an objective function, the value of the power index is equal to zero for almost all studied cases.
Journal of Structural and Construction Engineering, Jun 1, 2016
Civil engineering infrastructures journal, Dec 1, 2010
Civil Engineering Journal, Nov 1, 2020
American Journal of Applied Sciences, Apr 1, 2008
International Journal of Engineering, Apr 1, 2012
International journal of engineering. Transactions B: Applications, Nov 1, 2017
2nd international conference on concrete repair, rehabilitation and retrofitting, ICCRRR-2, Nov 24, 2009
Mechanics of Advanced Materials and Structures, 2021
The current literature deals with the multi-objective optimal material distribution of porous fun... more The current literature deals with the multi-objective optimal material distribution of porous functionally graded plates subjected to free vibration in the framework of Carrera Unified Formulation ...
Sustainability, 2004
The free vibration of Timoshenko beams with varying cross-section is reduced to an analytical sol... more The free vibration of Timoshenko beams with varying cross-section is reduced to an analytical solvable standard differential equation. This equation form depends on the specific moment of inertia, cross-section area and mass variation. The more accurate mode shapes and natural frequencies can be obtained by combining the effects of shear and flexural deformation. In this paper the main differential equation of vibration which involves flexural and shear effects (Timoshenko beam without rotary inertia effect) is obtained. The general solution of the main vibration equation has been derived by selecting suitable expressions such as power and exponential functions for the stiffness and mass distribution. Tall structures can be treated as cantilever beams with variable cross-section for their free vibrational analysis. The natural frequencies and mode shapes of tall buildings can be obtained by applying the proposed general solution of Timoshenko beams with varying cross-section. The ca...
Light weight construction is one of topics in civil engineering, the topic of reducing weight of ... more Light weight construction is one of topics in civil engineering, the topic of reducing weight of structure achieves by use of new technique stuction and optimization of procedure construction. Consideration to wide use of concrete and enviromental pollution to the reason of using cement, investigators are trying to replacement of a part of cement by natural and artifitial pozzolan and nano particle and etc. In this study natural pozzolan zeolite as replacement admixture with different percents 0, 5, 10, 15, 20 investigated and longterm and short term effects on the compression and tensile strenght on half light weight concrete at the age 3, 56, 90 days were studied and compared with control specimen. Result shows that 5% and 10% replacement of zeolite improve compression strength at the age of 3, 90 days, and for age of 56 days most improvement is related to 15% replacement by zeolite.
2nd International Conference on Concrete Repair, Rehabilitation and Retrofitting, ICCRRR-2, 24-26 November 2008, Cape Town, South Africa, 2008
American Journal of Applied Sciences, 2008
American Journal of Applied Sciences, 2007
Carbon fiber reinforced polymer (CFRP) has been widely used to strengthen steel members in bendin... more Carbon fiber reinforced polymer (CFRP) has been widely used to strengthen steel members in bending. Few research studies have been carried out on strengthening steel members under axial load strengthening by CFRP. The purpose of this study is to evaluate the compressive load capacity of Square Hollow Section (SHS) steel short and slender columns strengthened using CFRP. The numerical analyses using Finite Element Method (FEM) obtained from ANSYS Software were utilized. The results have been verified by experimental analyses. The results showed that CFRP wraps are capable of increasing the compressive load capacity of SHS steel short and slender columns appropriately. In addition when coverage percent CFRP layers was less 100%, CFRP more increased the compressive load capacity of SHS steel slender columns. The numbers of CFRP layers were effective in the compressive load bearing capacity of SHS steel short and slender columns.
Iran University of Science & Technology, 2020
The utilization of passive energy dissipation systems has been created a revolution in the struct... more The utilization of passive energy dissipation systems has been created a revolution in the structural engineering industry due to their advantages. Fluid Viscous Damper (FVD) is one of these control systems. It has been used in many different industries, such as the army, aerospace, bridge, and building structures. One of the essential questions about this system is how it can combine with the bracing system to enhance its abilities. In this paper, a comparison between the responses of a twelve-story steel building retrofitted by four layouts of bracings systems (i.e., chevron, diagonal, toggle, and X-brace) is studied. These bracing systems are equipped by FVD to find the optimum layout for these systems. Buildings are modeled nonlinearity and excited by an earthquake (Manjil earthquake). For this purpose, the Fast Nonlinear Analysis (FNA) is performed using the SAP2000 software. The results show that FVD alters some of the structural behaviors such as inter-story drift when combin...
Journal of Constructional Steel Research, 2008
Mechanics of Advanced Materials and Structures
This paper investigates the bending and vibration characteristics of metallic and functionally gr... more This paper investigates the bending and vibration characteristics of metallic and functionally graded (FG) beam structures. The weak form of governing equations and boundary conditions are derived using Carrera unified formulation (CUF). The isogeometric analysis (IGA) is employed to solve the static and free vibration problems. NURBS basis functions approximate the displacement field unknowns and material gradations in cross-section. In contrast, the axial displacements are evaluated by either NURBS or Lagrange basis functions. In this framework, the equations are extracted in the form of a fundamental nucleus, which allows the study of different beam theories in a constant formulation. Several numerical examples are presented and compared with results available in the literature to address the accuracy and effectiveness of the current approach. It is found that the present results are validated for different aspect ratios, boundary conditions, and material distribution with more accuracy and low computational cost.
The sensitivity of tall buildings subjected to the lateral loads is more than that of the gravity... more The sensitivity of tall buildings subjected to the lateral loads is more than that of the gravity loads. Therefore, the conventional methods are not efficient yet, and new methods such as the use of the belt truss and outrigger systems are proposed by designers to reduce the structural roof displacement, shear lag, overturning moment, and also to increase the lateral resistance of the structures. In the design of tall structures, for economic reasons, it is desirable to reduce the lateral stiffness of the structures along with the height of the structure. In this paper, the framed tube and shear core are modeled using the energy method and the continuous beam model. The optimum location of the belt truss and outrigger system are calculated considering three lateral loading patterns. It is assumed that the lateral stiffness of the framed tube and shear core varies along with the height of the structure. The stiffness of the belt truss and outrigger system is also considered as an equ...