Effect of Aspect Ratio on High Rise Structures with Diagrid

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
A. Vimala ◽  
A. Vimala
Keyword(s):  
Aspect Ratio ◽  
Numerical Study ◽  
Percentage Increase ◽  
Base Shear ◽  
High Rise ◽  
Aspect Ratios ◽  
Drift Ratio ◽  
Time Period ◽  
Diagrid Structure ◽  
Building Behaviour

Urbanization and population explosion in the present times has led to increase in demand for land and residencies but the availability of land is scare i.e reason a trend has evolved for construction of high rise structures in high rise structures major emphasis given to lateral load resisting systems. As diagrid structural system is lighter, stiffer and is effective in resisting the lateral loads, the present investigation carried out to study the performance diagrid on high rise structures varying aspect ratio. The study is carried out to observe the performance of diagrid structures ranging from 30 to 90 storeys. Diagrid structures are modelled with 3 storey module and performance of 7 models with different storeys i.e 30, 40, 50, 60, 70, 80, 90 (aspect ratio 3.67-10.86) and with fixed plan area. As a part 1 investigation to optimise the diagrid angle a 30 storey Diagrid structure performance is studied with 4 different diagrid angles one storey module angle 35°45’, Two storey module angle 55°13’, Three storey module 65°9’, Four storey module 70°51’. The optimized diagrid angle is used for different aspect ratio high rise structures to investigate the performance in terms of Storey displacement, Storey drift ratio, base shear and time period. For all the models plan area is fixed. Second part of investigation was a numerical study carried out by utilizing identified optimum angle of diagrid is applied on high rise buildings with aspect ratios 3.67, 4.86, 6.06, 7.26, 8.46, 9.67, 10.86 (Aspect ratio is the total height of the building to the width of the building). Behaviour of the Diagrid buildings due to change in aspect ratio is analysed based on parameters such as Storey displacements, Storey drift ratio, Base shear, Time period. As a part of investigation parameters such as Storey displacements and storey drift ratio were evaluated if they were within the limits as per IS code provisions. Percentage increase in storey displacements, maximum storey drift ratio,

Optimization of Diagrid Angle for High Rise Structure for Varying Bay Widths

2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Kathi Lavanya ◽  
A. Vimala
Keyword(s):  
Numerical Study ◽  
Comparative Investigation ◽  
Structural Systems ◽  
Lateral Loads ◽  
Structural System ◽  
Base Shear ◽  
High Rise ◽  
Gravity Load ◽  
Structural Responses ◽  
Diagrid Structure

The development of urban population, the lack of space and the high land costs has created the scope and necessity for the high-rise structures. In high rise structures, the design of lateral load resisting systems is more crucial than gravity load resisting system. There are many structural systems exists in literature to resist lateral loads. Diagrid structure is one among them which is proven to be both structurally and architecturally efficient structural system to resist lateral loads. The present study aims to investigate the best bay spacing for a particular high-rise structure and also optimizing the best diagrid angle to suit to the selected bay spacing. A numerical study is carried out with a 24 storied high-rise structure of plan area 36m x 36m considering with and without corner columns. The structure performance is checked with a bay width of 4m and with a bay width of 6m. Each structure is analyzed for four angles of inclinations of diagrid are formed by connecting 1, 2, 3, 4 stories respectively to optimize the diagrid angle. A comparative investigation is carried out for the structural responses like storey displacement, storey drift and base shear with different diagrid angles and with different bay width.

scholarly journals Fracture Shape and Orientation Contributions to P-Wave Velocity and Anisotropy of Alpine Fault Mylonites

2021 ◽  
Vol 9 ◽  
Author(s):  
Jirapat Charoensawan ◽  
Ludmila Adam ◽  
Michael Ofman ◽  
Virginia Toy ◽  
Jonathan Simpson ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Shear Zone ◽  
Numerical Study ◽  
Numerical Models ◽  
Propagation Model ◽  
P Wave ◽  
Micro Ct ◽  
Alpine Fault ◽  
Aspect Ratios ◽  
Ct Data

P-wave anisotropy is significant in the mylonitic Alpine Fault shear zone. Mineral- and texture-induced anisotropy are dominant in these rocks but further complicated by the presence of fractures. Electron back-scattered diffraction and synchrotron X-ray microtomography (micro-CT) data are acquired on exhumed schist, protomylonite, mylonite, and ultramylonite samples to quantify mineral phases, crystal preferred orientations, microfractures, and porosity. The samples are composed of quartz, plagioclase, mica and accessory garnet, and contain 3–5% porosity. Based on the micro-CT data, the representative pore shape has an aspect ratio of 5:2:1. Two numerical models are compared to calculate the velocity of fractured rocks: a 2D wave propagation model, and a differential effective medium model (3D). The results from both models have comparable pore-free fast and slow velocities of 6.5 and 5.5 km/s, respectively. Introducing 5% fractures with 5:2:1 aspect ratio, oriented with the longest axes parallel to foliation decreases these velocities to 6.3 and 5.0 km/s, respectively. Adding both randomly oriented and foliation-parallel fractures hinders the anisotropy increase with fracture volume. The anisotropy becomes independent of porosity when 80% of fractures are randomly oriented. Modeled anisotropy in 2D and 3D are different for similar fracture aspect ratios, being 30 and 15%, respectively. This discrepancy is the result of the underlying assumptions and limitations. Our numerical results explain the effects that fracture orientations and shapes have on previously published field- and laboratory-based studies. Through this numerical study, we show how mica-dominated, pore-free P-wave anisotropy compares to that of fracture volume, shape and orientation for protolith and shear zone rocks of the Alpine Fault.

scholarly journals Effect of Shear Wall on RC Building of Varying Heights

2019 ◽  
Vol 8 (12) ◽  
pp. 766-770
Keyword(s):  
Aspect Ratio ◽  
Response Spectrum ◽  
Shear Walls ◽  
Shear Wall ◽  
Seismic Zone ◽  
Lateral Loads ◽  
Base Shear ◽  
Aspect Ratios ◽  
Rc Building ◽  
The Comparative Study

Earthquake is an unexpected and expensive disaster for both livelihood and economy. In the modern day construction, there has been a lot of importance to make the structure resistant against lateral loads for multi storied building. Shear walls are an option of lateral load resisting system. The Concept of designing shear wall is to provide building structure with sufficient strength and deformation capacity to sustain the demands imposed by lateral loads with adequate margin of safety. The study focuses on effect of shear wall on R.C. building at different heights. For this purpose five models of different heights 15m, 30m, 45m, 60m and 75m and with different aspect ratios of 1.33, 0.66, 0.44, 0.33 and 0.26 respectively have been considered. All the models were designed for seismic zone V. For analysis purpose response spectrum method of analysis is considered as per IS: 1893-2002. The comparative study has been done for base shear, storey displacement, storey drift and storey stiffness. Utilization of shear walls when placed at corners of the building of low aspect ratio in high rise buildings is more effective compared to the low rise buildings of higher aspect ratio, as it gives the larger base shear and lesser displacement. The storey stiffness and storey drift is greatly improved when shear wall is placed at corners of the building

scholarly journals Analog Search of Different Lateral Load Resisting System for High Rise Building

2019 ◽  
Vol 8 (2S3) ◽  
pp. 476-480
Keyword(s):  
Tall Buildings ◽  
Lateral Load ◽  
Exterior Surface ◽  
High Rise ◽  
Column System ◽  
Time Period ◽  
Exhaustive Study ◽  
Strength And Stiffness ◽  
Diagrid Structure ◽  
Seismic Forces

As the rate of growth of population is increasing day by day, the requirement of land is increasing for different purposes. To accommodate this increased population, the height of building is increasing thereby subsequently increasing the importance of lateral load resisting system which provide adequate strength against lateral loading arising due to earthquake and wind. In present study various lateral load resisting system have been introduced which can resist the lateral forces and safely transfer them to soil thereby improving the strength and stiffness of column structures. The lateral load resisting systems that are widely used are conventional beam column system, shear wall system, tube system, outrigger system, tubular system etc. Diagrid structural system is generally adopted in tall buildings due to its structural efficiency and flexibility in planning. Compared to closely space vertical columns in Conventional Beam column system, diagrid structure consists of inclined columns on the exterior surface of building. The concrete diagrids member is used in both precast and cast in-situ type. An exhaustive study has been performed on the performance of 20 storey RCC building with plan size 18 m × 18 m using E-TAB software. All structural members are designed as per IS 456:2000 and all the load combinations of seismic forces are considered as per IS 1893(Part 1): 2002. Finally, Parameter such as storey displacement, storey stiffness and time period are compared and obtained results were presented in both graphically and tabular format

Cross-Wind Influence on Low Aspect Ratio Wings at Low Reynolds Numbers

2013 ◽  
Author(s):  
Amir Karimi Noughabi ◽  
Mehran Tadjfar
Keyword(s):  
Aspect Ratio ◽  
Numerical Study ◽  
Three Dimensional ◽  
Micro Air Vehicles ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Low Aspect Ratio ◽  
Aspect Ratios ◽  
Lift And Drag ◽  
Lift And Drag Coefficient

The aerodynamics of the low aspect ratio (LAR) wings is of outmost importance in the performance of the fixed-wing micro air vehicles (MAVs). The flow around these wings is widely influenced by three dimensional (3D) phenomena: including wing-tip vortices, formation of laminar bubble, flow separation and reattachment, laminar to turbulent transition or any combination of these phenomena. All the recent studies consider the aerodynamic characteristics of the LAR wings under the effect of the direct wind. Here we focus on the numerical study of the influence of cross-wind on flow over the inverse Zimmerman wings with the aspect ratios (AR) between 1 and 2 at Reynolds numbers between 6×104 and 105. We have considered cross-wind’s angles from 0° to 40° and angle of attack from 0° to 12°. The results show that lift and drag coefficient generally decrease when the angle of the cross-wind is increased.

scholarly journals Impact of Variation in Plan Configuration on Structural Behaviour of Reinforced Concrete Building

2021 ◽  
Vol 9 (VIII) ◽  
pp. 495-505
Author(s):  
Akshit Kumar Ketanbhai Ravat
Keyword(s):  
Reinforced Concrete ◽  
Aspect Ratio ◽  
Population Increase ◽  
Centre Of Mass ◽  
Base Shear ◽  
Structural Behaviour ◽  
High Rise ◽  
Concrete Building ◽  
Structural Engineers ◽  
Day By Day

Nowadays high rise building is a new trend in India because day by day population increase and it’s a problem to accommodate large number of people in small place. To resolve this problem only one option is good which is vertical growth of building. Due to architectural purpose some building’s plan like L, C, E and + etc. cause plan irregularities and in elevation like vertical set-back type building cause vertical irregularities. These kind of shapes are creating problem for structural engineers because it demands serious damage in earthquake. In this study the main objective is to understand demand of lateral load on different plan aspect ratio and with varying heights of 18, 33 and 48meter. Modelling of varying heights OF 18, 33 and 48 meter R.C.C. framed building is done on the ETABS software for analysis. Post analysis of the structure, Centre of mass, Centre of resistance of building, maximum storey displacement, storey drift and base shear are computed and then compared for all the analyzed cases.

scholarly journals Numerical Study on the Effect of Tunnel Aspect Ratio on Evacuation with Unsteady Heat Release Rate Due to Fire in the Case of Two Vehicles

Energies ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 133 ◽  
Author(s):  
Younggi Park ◽  
Youngman Lee ◽  
Junyoung Na ◽  
Hong Sun Ryou
Keyword(s):  
Aspect Ratio ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Numerical Study ◽  
Longitudinal Direction ◽  
Release Rates ◽  
Aspect Ratios ◽  
Visibility Distance ◽  
Computational Fluid Dynamics Analysis

In this study, the characteristics of fires in case of two vehicles in a tunnel are analyzed by Computational Fluid Dynamics analysis for varying tunnel aspect ratios. Unsteady heat release rates over time are set as the input conditions of fire sources considering real phenomena. Unsteady heat release rate values are obtained from experiments. As a result, the smoke velocities above the fire source appear faster in the case of tunnels with a large aspect ratio because the higher the height of the tunnel, the faster the smoke velocity caused by buoyancy forces. The smoke velocity in the longitudinal direction increases quickly. However, the temperature distribution in the vicinity of the ceiling is low when the tunnel aspect ratio is large because the height of the tunnel is not directly affected by the flames. Also, the higher the height of the tunnel, the lower the visibility distance due to the heat and smoke coming down along the wall surface. However, in the tunnels represented in this study, it is considered that the visibility of evacuees is sufficiently secured.

scholarly journals Analysis of Aspect Ratio Effects on Transonic Rotor Performance Using a 3D Viscous Solver

1998 ◽  
Author(s):  
Cecil R. Buchanan ◽  
Paul R. Emmerson ◽  
Michael Spruce
Keyword(s):  
Aspect Ratio ◽  
Numerical Study ◽  
Navier Stokes ◽  
Test Cases ◽  
Compressor Rotor ◽  
Aspect Ratios ◽  
Radial Profiles ◽  
Ratio Change ◽  
The One ◽  
Good Agreement

This paper presents the results of a numerical study into the effects of aspect ratio on compressor rotor performance. The test cases studied are NASA rotors 37 and 38, which have aspect ratios of 1.19 and 1.63 respectively. A 3D, single-passage steady flow Navier-Stokes solver was used to predict complete performance characteristics, including the numerical instability point, for both rotors. The predictions are generally in good agreement with the test data (characteristics, radial profiles and rotor over tip measurements) at all conditions modelled for rotor 37. The performance for rotor 38 is overpredicted, with slightly less than half of the measured performance difference between the two rotors being captured. The effect of a pure aspect ratio change (divorced from the rotor inlet to exit area changes present in the rotor 37/38 comparisons) was also investigated, and a case with an aspect ratio double that of rotor 37 was also modelled. The results indicated that the code predicted little effect on rotor performance due to an aspect ratio change alone (from 1.19 to 2.38). This is surprising and it raises doubts about the ability of current codes (or at least the one used in the study) to predict this important aspect of a compressor design adequately.

Effect of Aspect Ratio on the Buoyancy Driven Reverse Flow Near the Leading Wall of Rotating Cooling Passages

1996 ◽  
Author(s):  
Prabhat Tekriwal
Keyword(s):  
Aspect Ratio ◽  
Rotation Number ◽  
Numerical Study ◽  
Reverse Flow ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Hydraulic Diameter ◽  
Flow Reversal ◽  
Aspect Ratios ◽  
Reversal Phenomenon

The present work is concerned with the flow reversal phenomenon that is caused by the centrifugal buoyancy forces in the case of three-dimensional radially outward flow through rectangular ducts rotating in orthogonal mode. Due to the flow reversal, regions of zero to low fluid velocity (stagnation) are created near the leading wall and the heat transfer, consequently, is impaired causing concerns for the design engineers. Three duct cross-sections of the same hydraulic diameter but different aspect ratios (1:1, 2:1 and 3.33:1) have been examined in this numerical study for flows at different rotation numbers and different temperature ratios. The rotation number examined ranged from 0.08 to 0.35. For each rotation number the temperature ratio is increased until the flow reversal phenomenon is observed in the CFD predictions. For all the three ducts, computations have been carried out for Reynolds number equal to 80,000. The onset of the flow reversal near the leading wall and at the exit of the single-pass flow passage is studied with the buoyancy number variation. As the aspect ratio is increased while keeping the duct hydraulic diameter fixed, the buoyancy number required to cause the onset of flow reversal decreases. Also, for each of the three ducts examined it has been found that the buoyancy number required for the predicted reverse flow to occur increases as the rotation number is increased.

Numerical Study of the Effect of Reynolds Number and Aspect Ratio in Heat Transfer from Elliptical Tubes to Viscoplastic Fluids Employing Constructal Design

2017 ◽  
Vol 372 ◽  
pp. 142-151
Author(s):  
Lober Hermany ◽  
Rafael José Klein ◽  
Flavia F.S. Zinani ◽  
Liércio André Isoldi ◽  
Elizaldo Domingues dos Santos ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
Numerical Study ◽  
Viscoplastic Fluid ◽  
Flow Index ◽  
Flow Acceleration ◽  
Viscoplastic Fluids ◽  
Aspect Ratios ◽  
Elliptical Section

The present work aims to obtain geometries that ease the heat transfer from elliptical section tubes to cross flow of viscoplastic fluids. The Construtal Design method is applied to obtain aspect ratios between the axes of the elliptic sections that maximize the Nusselt number. The tubes elliptical section area is fixed, but the aspect ratio between their axes is free to change in order to optimize this geometry for different Reynolds numbers (Re). The viscoplastic fluid behavior is modeled using the Herschel-Bulkley constitutive equation for the viscosity function. The governing differential equations are solved numerically by the finite volume method. The values of the dimensionless numbers, Prandtl (Pr), modified Bingham (Bn*) and flow index (n), were kept constant and equal to 1, 1 and 0.4, respectively. The Reynolds number was varied from 1 to 40. The results obtained show that increasing the number of Reynolds results in a greater heat transfer. In addition, the optimal aspect ratio is smaller the greater the Reynolds number is. It was found that, as the aspect ratio grows, heat transfer increases due to flow acceleration, but also decreases due to the low strain rate zone downstream the tube, which possesses recirculation and unyielded material. The balance between these effects gives the optimum point.

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