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Open Access Article
1 - Wind tunnel flow simulation and aerodynamic shape optimization of tall buildings to improve the drag coefficient under wind forces
Abdollah Baghaei Daemei seyed rahman eghbali Hossein Moez Payam BahramiAerodynamic behavior is an important characteristic of tall and ductile buildings, so aerodynamic design can play a key role in reducing the wind effects. A tall building response to wind can be controlled by application of aerodynamic improvements to building’s d MoreAerodynamic behavior is an important characteristic of tall and ductile buildings, so aerodynamic design can play a key role in reducing the wind effects. A tall building response to wind can be controlled by application of aerodynamic improvements to building’s design in order to manipulate the wind flow pattern and break the effective wind force acting on the structure. Traditionally the approach of structural engineers to mitigating wind loading and associated deflections and motions on tall buildings was to stiffen the building with the aim of increasing the natural frequency. Tall buildings are extremely sensitive to the wind. Thus, assessment of wind loads to design these buildings is essential. Monitoring the wind, which is forcing extraordinary tall buildings, is highly challenging. Due to increasing construction in recent decades, the study on wind flow over tall buildings has become a popular subject in theoretical research and applied engineering applications. By looking at recent constructions in Iran, it is obvious that despite the fact that constructing tall buildings is spreading, there is less concentration on environmental factors such as the wind’s aerodynamic. In tall buildings, aerodynamic behavior generally becomes important. The wind-induced building response of tall buildings can be reduced by means of aerodynamic from design and modifications that change the flow pattern around the building or break up the wind affecting the building face. Aerodynamic-based design can be divided into two types, “aerodynamic architectural design” and “aerodynamic architectural modifications” and their subgroups. The accurate estimation of the critical response parameters, such as top floor accelerations and displacements, is of fundamental importance when ensuring reliable designs of tall buildings. Methods to this end are typically set in a modal analysis framework and therefore require the estimation of the generalized forcing functions. Tall buildings are particularly prone to dynamic excitations such as those from natural disasters like strong winds and earthquakes, and this has become an especially important design issue. One way to minimize wind-induced vibrations of tall buildings is to focus more on their shapes in the design stage. Investigated aerodynamic forces and wind pressures acting on tall buildings with various unconventional configurations. The proposed of this research, investigation of aerodynamic shape optimization on tall buildings in order to reduce drag force. The aerodynamic forms such as a set-back, tapered and helical (twisted) and also aerodynamic modifications such as a chamfered corner, rounded corner and recessed corner to control and reduce wind forces and vortices on tall buildings are considered. On this basis, the study was carried out with numerical simulation of wind tunnel test on 29 building models. In order to construct 3D models, AutoCAD 2014 software was deployed and also to numerically simulate wind tunnel Autodesk Flow Design 2014 is used. Building samples were entered into the software via format FBX. The results showed that for a tall building with a triangular footprint and height of about 150 meters, base shape with chamfered corners of aerodynamic modification and tapered of aerodynamic form can have the best aerodynamic behavior against wind forces. Manuscript profile -
Open Access Article
2 - Investigating the wind-induced effects on Tall Buildings to reduce Drag Coefficient through Large Eddy Simulation (LES)
Najmeh Mastari Farahani Abdollah Baghaei Daemei Payam Madelat Seyedeh Maryam Abbaszadegan -
Open Access Article
3 - Designating a procedure for appropriate development of Tall Building in Iran: Regulating an ongoing process to reduce its negative consequences
Ghazal Raheb Ali Tayebi Elham Zabetian Targhi -
Open Access Article
4 - Evaluation of Seismic Performance of Combined Horizontal and Vertical Hexagrid Structural System for High-rise Buildings
Yasaman Memarzadeh Kiani Maryam Firoozi Nezamabadi -
Open Access Article
5 - Comparison of exploitation criteria and acceleration of diagrid steel structures with tube system based on wind dynamic analysis
mehdi hooshmand Hassan Haji Kazemi Seyed Alireza ZareeiConsidering the widespread use of diagrid systems in high-rise buildings, it seems necessary to investigate the behavior of this structural system against the wind and control comfort criteria based on acceleration. The purpose of this research is to compare the comfort MoreConsidering the widespread use of diagrid systems in high-rise buildings, it seems necessary to investigate the behavior of this structural system against the wind and control comfort criteria based on acceleration. The purpose of this research is to compare the comfort criterion based on acceleration in the diagrid system with the tube system. For this purpose, the effect of various parameters such as the acceleration of floors and base shear under dynamic wind load has been evaluated. It is expected that the performance of the diagonal network will be evaluated with a more detailed understanding of the diagonal network in tall structures and the evaluation of the performance and comfort criteria based on the acceleration against the wind load using the dynamic analysis of time history using Cholsky, ergodic and AP methods. Investigations show that the acceleration of the diagrid system floors, based on the ASCE7 wind dynamic response prediction equations, has exceeded the permissible limit of the ASCE 7 regulation of milli-g20. This article is due to the overestimation of ASCE 7 equations compared to the results of wind time history analysis. So, in the 50-story structure, the maximum acceleration of the roof obtained from the ASCE equation is 71.83 times the results of the dynamic analysis of wind time history, and in the 70-story structure, it is 2 times, and in the 100-story structure, it is 1.87 times the results of the dynamic analysis of the wind time history. Manuscript profile -
Open Access Article
6 - Optimized Designing of the Diametric Network of one or two-layer Diagrid Structure in Dignified Buildings under the Gravity and Lateral Loads
ashkan khodabandelou reza aghajani Diagrid structures as the structural system in dignified buildings, from the applicational point of view, are framed and piped developed structures which decrease the weight of the structure by reducing the cutting limp. The goal of the pr More Diagrid structures as the structural system in dignified buildings, from the applicational point of view, are framed and piped developed structures which decrease the weight of the structure by reducing the cutting limp. The goal of the present article is to optimize the diagrid structures for reducing the weight of structure, determining the number of classifications and the optimize angle and finally comparing the mono and two-layer diagrid structure for selecting the economic option. Through the present research, doing the optimizing diagrid structure by using the extra-creating algorithms, which made the integrated drive electronic necessary, was considered. The Grasshopper graphical programming extension on the Rhino geometric modelling software supplied the algorithmic optimization by making the written program parametric by the genetic algorithm by Galapagos extension. Optimizing in the written software is done by the genetic algorithm by Galapagos extension in base of output results from Karamba analysis structure engine. The optimizing accessed results show that the optimizing angle of the diagrid structures’ members with horizon line for mono-layer diagrid os 64/01 and for two-layer diagrid structure is 65/77. The optimizing weight of the mono-layer diagrid is less than two-layer diagrid which by attention to the simple structure in the rapid time and less energy consuming, the mono-layer diagrid is selected as the affordable option. Manuscript profile -
Open Access Article
7 - Optimal design of diagrid steel structure in high building
ashkan khodabandelou reza aghajaniDiagrid structure is diagonal elements that simultaneously carry the load of horizontal and vertical loads. In diagrid structures, unlike most common systems of high-rise buildings in which incoming loads are transmitted through shear and flexural mechanisms, the MoreDiagrid structure is diagonal elements that simultaneously carry the load of horizontal and vertical loads. In diagrid structures, unlike most common systems of high-rise buildings in which incoming loads are transmitted through shear and flexural mechanisms, the diagrid structures, due to their triangular configuration and removal of vertical columns, have a central load transfer mechanism, in other words, they have truss performance. Diagrid structures are developed for effectiveness and beauty of architecture and structure.Diagrid structures as a structural system in high-rise buildings in terms of performance, is an improved system of frame and pipe structure, which reduces the structural weight by decreasing the shear lag. The goal of this research is to optimize the diameter structure of buildings to minimize the weight of the structure, to determine the number of horizontal and vertical segments. Grasshopper graphical programming plugin for Rhino software, with parameterization of the written program, provides algorithm optimization. Optimization in the program written by the genetic algorithm is done through the Galapagos plugin based on the outcomes of the structure analysis engine of the Karamba plugin. The simulation results indicate that for a 40-store diameter structure of 900 square meters in each floor, the optimal mode with the horizontal and vertical divisions of 8, and 26, and the angle of 64 with the horizontal axis will be 21508 tons of the total structure. Manuscript profile -
Open Access Article
8 - Comparison of Exploitation Criteria and Acceleration of Long Diagrid Steel Structures with Environmental Frame System Based on Dynamic Wind Analysis
mehdi hooshmand Hassan Haji Kazemi Seyed Alireza ZareeiConsidering the widespread use of diagrid systems in tall buildings, it is necessary to investigate the behavior of this structural system against the wind and control comfort criteria based on acceleration. According to different regulations, it is evident that there i MoreConsidering the widespread use of diagrid systems in tall buildings, it is necessary to investigate the behavior of this structural system against the wind and control comfort criteria based on acceleration. According to different regulations, it is evident that there is not much guidance for the design of this structural system and its requirements have not yet been included in the design regulations. Therefore, one of the most important goals of the current research is to investigate and use the Diagrid structural system as one of the modern structural systems in high-rise buildings. Another goal of this research is to compare the performance of the diagrid system with the environmental pipe system. Accordingly, the effect of various parameters including the acceleration of floors and shear of the base under dynamic wind load has been evaluated. It is expected that the performance of the diagonal network will be evaluated with a more detailed understanding of the diagonal network in tall structures and the evaluation of the operation and comfort criteria based on the acceleration against the wind load using dynamic time history analysis applying Cholesky, ergodic and AP methods. The results have been compared with the formulas of the ASCE7 regulation and the AIJ-GBV-2004 and ISO 10137:2007 comfort criteria and the National Building Code of Canada (NBCC). These investigations indicate that the acceleration of the diagrid system floors based on ASCE7 wind dynamic response prediction equations, has exceeded the permissible limit of ASCE 7 regulation by 20 milli-g (20Gal). This is due to the high estimation of ASCE 7 equations compared to the results of wind time history analysis. In such a way that in the 50-, 70-, and 100-story buildings, the maximum accelerations of the roof obtained from the ASCE 7 equation are 1.83, 2.07, and 1.87 times the results of the dynamic analysis of wind time history, respectively. Manuscript profile -
Open Access Article
9 - Comparison of the Capacity of Three Types of Lateral Resisting Systems in the Design of a 45-Story Steel Building
shahab Emamzadeh Amin JavanmardiIn this research, the strengths and weaknesses of lateral systems of tall buildings are identified and a suitable system is proposed both technically and economically. In this regard, for a hypothetical 45-storey building, three types of pipe in pipe system with truss b MoreIn this research, the strengths and weaknesses of lateral systems of tall buildings are identified and a suitable system is proposed both technically and economically. In this regard, for a hypothetical 45-storey building, three types of pipe in pipe system with truss belt cap, moment frame system with truss belt cap and central core system with restraint arm and truss belt are compared. Nonlinear analysis of the structure was performed by pushover method. In addition, the relative displacement of the floors was extracted by ETABS software. The results revealed that the central core system with the restraint arm and truss belt in a hypothetical 45-storey building is economically more viable than other systems. Another consequence is that the closer the truss belt is to the ground floors, the better the performance of the structural system. Although this makes the bracing sections heavier, it will not have much effect on the overall weight of the structure. Manuscript profile -
Open Access Article
10 - Seismic Evaluation of Tall Buildings with End Shear Walls by Fragility Curve
Ali Kheyroddin Mehran Akhavan Salmassi Ali Hemmati -
Open Access Article
11 - Response of the Wind Excited Benchmark Building Upgraded with SAEMFDs
Veeranagouda B. Patil
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