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LES simulations of wind-induced pressure on the floor system underside of elevated buildings
Mehrshad Amini,Ali M. Memari 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.5
Recent hurricanes have shown that coastal elevated houses are still vulnerable to wind-induced damage, mostly to envelope systems. This paper discusses the performance of elevated houses against hurricane wind loads, particularly wind flow characteristics and the distribution of the peak pressure coefficient (Cp_min) corresponding to the underside of the floor system. Computational fluid dynamics (CFD) analysis was utilized to investigate the effect of interior piers and the wind direction (0 ° ,45° , and 90° ) on the distribution and the magnitude of Cp_min. The CFD results show that the distribution of Cp_min and its maximum value are dependent on pier distribution (e.g., pier location and spacing) and wind direction. The distribution of Cp_min for the 90° wind direction is more similar to the 0 ° wind direction, but the leeward parts of the floor system are exposed to higher negative pressures. The maximum of Cp_min belongs to the 45° wind direction, which occurs at the windward edge and behind the interior pier due to recirculation zones and subsequent vortices. The results of this study indicate that current design standards and provisions need to be updated to include proper design requirements for the floor system, particularly around piers, to help reduce direct/indirect wind-induced damage to elevated houses in coastal areas.
BEPAT: A platform for building energy assessment in energy smart homes and design optimization
Kamel, Ehsan,Memari, Ali M. Techno-Press 2017 Advances in energy research Vol.5 No.4
Energy simulation tools can provide information on the amount of heat transfer through building envelope components, which are considered the main sources of heat loss in buildings. Therefore, it is important to improve the quality of outputs from energy simulation tools and also the process of obtaining them. In this paper, a new Building Energy Performance Assessment Tool (BEPAT) is introduced, which provides users with granular data related to heat transfer through every single wall, window, door, roof, and floor in a building and automatically saves all the related data in text files. This information can be used to identify the envelope components for thermal improvement through energy retrofit or during the design phase. The generated data can also be adopted in the design of energy smart homes, building design tools, and energy retrofit tools as a supplementary dataset. BEPAT is developed by modifying EnergyPlus source code as the energy simulation engine using C++, which only requires Input Data File (IDF) and weather file to perform the energy simulation and automatically provide detailed output. To validate the BEPAT results, a computer model is developed in Revit for use in BEPAT. Validating BEPAT's output with EnergyPlus "advanced output" shows a difference of less than 2% and thus establishing the capability of this tool to facilitate the provision of detailed output on the quantity of heat transfer through walls, fenestrations, roofs, and floors.
Ductility-based seismic design of precast concrete large panel buildings
Astarlioglu, Serdar,Memari, Ali M.,Scanlon, Andrew Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.10 No.4
Two approximate methods based on mechanism analysis suitable for seismic assessment/design of structural concrete are reviewed. The methods involve use of equal energy concept or equal displacement concept along with appropriate patterns of inelastic deformations to relate structure's maximum lateral displacement to member and plastic deformations. One of these methods (Clough's method), defined here as a ductility-based approach, is examined in detail and a modification for its improvement is suggested. The modification is based on estimation of maximum inelastic displacement using inelastic design response spectra (IDRS) as an alternative to using equal energy concept. The IDRS for demand displacement ductilities are developed for a single degree of freedom model subjected to several accelerograms as functions of response modification factor (R), damping ratios, and strain hardening. The suggested revised methodology involves estimation of R as the ratio of elastic strength demand to code level demand, and determination of design base shear using $R_{design}{\leq}R$ and maximum displacement, determination of plastic displacement using IDRS and subsequent local plastic deformations. The methodology is demonstrated for the case of a 10-story precast wall panel building.
Liang, Jianhai,Memari, Ali M. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.38 No.1
Brick veneer over steel stud backup wall is lighter and easier to construct compared to brick veneer over concrete masonry backup wall. However, due to the relatively low stiffness of the steel stud backup, the brick veneer tends to crack under wind load. This paper briefly introduces a new panelized brick veneer with steel frame backup wall system that is developed to potentially address this problem. The experimental study of the performance of this system under simulated wind loading is discussed in detail. The test setup details and the test specimens are introduced, results of major interests are presented, and performance of the new system is evaluated based on the test results.
Jianhai Liang,Ali M. Memari 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.38 No.1
Brick veneer over steel stud backup wall is lighter and easier to construct compared to brick veneer over concrete masonry backup wall. However, due to the relatively low stiffness of the steel stud backup, the brick veneer tends to crack under wind load. This paper briefly introduces a new panelized brick veneer with steel frame backup wall system that is developed to potentially address this problem. The experimental study of the performance of this system under simulated wind loading is discussed in detail. The test setup details and the test specimens are introduced, results of major interests are presented, and performance of the new system is evaluated based on the test results.