scholarly journals Prognosis of Wind-tempted Mean Pressure Coefficients of Cross-shaped Tall Buildings Using Artificial Neural Network

2020 ◽  
Author(s):  
Rajdip Paul ◽  
Sujit Kumar Dalui
Keyword(s):  
Mean Squared Error ◽  
Pressure Coefficient ◽  
Tall Buildings ◽  
Parametric Models ◽  
Wind Pressure ◽  
Pressure Coefficients ◽  
Building Models ◽  
Wide Range ◽  
Close Relationship ◽  
Artificial Neural

The present paper focuses on the study of wind-induced responses of cross-plan shaped tall buildings. Initially, three parametric building models are studied for the purpose with a constant plan area 22500 mm2. The length and velocity scales are taken as 1:300 and 1:5, respectively. Wind angle of attack (WAA) is considered from 0° to 330° with an increment of 30°. At first, the external surface pressure coefficients (Cp) at different faces of the models are carried out for different wind occurrence angles employing Computational Fluid Dynamics method of simulated wind flow. Again, Fast Fourier Transform (FFT) fitted expressions as the sine and cosine function of WAA are proposed for attaining mean wind pressure coefficient on the building faces. The accuracy of the Fourier series expansions is justified by presenting histograms of sum square error (SSE), R2 value and root mean square error (RMSE). The results are also compared by training Artificial Neural Networks (ANN). Training is continued till Regression (R) values are more than 0.99 and Mean Squared Error (MSE) tends to 0, ensuring a close relationship among the outputs and targets. The face-wise value of (Cp) obtained using all three methods, are plotted. The error histograms of the ANN models show that the fitting data errors are spread within a reasonably good range. It is observed that the deviation in the result is not more than 5% in any case. Finally, the ANN predictions are presented for nine parametric models to cover a wide range of possible cross-shaped buildings.

scholarly journals Probability Characteristics, Area Reduction, and Wind Directionality Effects of Extreme Pressure Coefficients of High-Rise Buildings

2021 ◽  
Vol 11 (15) ◽  
pp. 7121
Author(s):  
Shouke Li ◽  
Feipeng Xiao ◽  
Yunfeng Zou ◽  
Shouying Li ◽  
Shucheng Yang ◽  
...  
Keyword(s):  
Probability Distribution ◽  
Pressure Coefficient ◽  
Wind Pressure ◽  
Extreme Pressure ◽  
Distribution Law ◽  
Distribution Fitting ◽  
Pressure Coefficients ◽  
High Rise ◽  
Area Reduction ◽  
The Mean

Wind tunnel tests are carried out for the Commonwealth Advisory Aeronautical Research Council (CAARC) high-rise building with a scale of 1:400 in exposure categories D. The distribution law of extreme pressure coefficients under different conditions is studied. Probability distribution fitting is performed on the measured area-averaged extreme pressure coefficients. The general extreme value (GEV) distribution is preferred for probability distribution fitting of extreme pressure coefficients. From the comparison between the area-averaged coefficients and the value from GB50009-2012, it is indicated that the wind load coefficients from GB50009-2012 may be non-conservative for the CAARC building. The area reduction effect on the extreme wind pressure is smaller than that on the mean wind pressure from the code. The recommended formula of the area reduction factor for the extreme pressure coefficient is proposed in this study. It is found that the mean and the coefficient of variation (COV) for the directionality factors are 0.85 and 0.04, respectively, when the orientation of the building is given. If the uniform distribution is given for the building’s orientation, the mean value of the directionality factors is 0.88, which is close to the directionality factor of 0.90 given in the Chinese specifications.

CFD Modeling of Pressure Coefficients for a Natural Ventilation Study in an Experimental Low Rise Building

2013 ◽  
Author(s):  
Robel Kiflemariam ◽  
Cheng-Xian Lin
Keyword(s):  
Natural Ventilation ◽  
Pressure Coefficient ◽  
Wind Pressure ◽  
Analytical Models ◽  
Cfd Modeling ◽  
Engineering Practice ◽  
Pressure Coefficients ◽  
Wind Pressure Coefficient ◽  
Detailed Assessment ◽  
Ventilation Rates

Mean wind pressure coefficient (Cp) is one of the major input data for natural ventilation study using building energy simulation approach. Due to their importance, they need to be accurately determined. In current engineering practice, tables and analytical Cp models only give mostly averaged results for simpler models and configurations. Considering the limitation of tables and analytical models, Computational Fluid Dynamics (CFD) could provide a means for an accurate and detailed assessment of Cp. In this paper, we make use of a relatively high resolution, detailed experiments done at Florida Intentional University to validate a CFD modeling of the pressure coefficients Cp. The results show that existing CFD model has a good agreement with experimental results and gives important information of distribution of Cp values over the surface. The local values of the Cp are investigated. In addition, the CFD derived Cp and discharge coefficient (Cd) values are utilized in semi-analytical ventilation models in order to get a more accurate value of ventilation rates.

scholarly journals Computational assessment of wind flow field on and around atypical buildings

2020 ◽  
Author(s):  
Rajasekarababu KB
Keyword(s):  
Surface Pressure ◽  
Pressure Coefficient ◽  
Tall Buildings ◽  
Ground Level ◽  
Pressure Variation ◽  
Middle Level ◽  
Computational Results ◽  
Pressure Coefficients ◽  
Building Surfaces ◽  
Side Face

Abstract This article provides an overview of pressure coefficients ( Cp ) on atypical tall buildings with the application of CFD. Various modifications in architectural shapes on tall buildings eventually lead to a reduction in the wind load on building surfaces. The surface pressure on conventional (Square and rectangular) buildings is relatively different in comparison to other tall buildings. This study is to evaluate the surface pressure coefficient over rectangular, taper and setback buildings. The computational results show that the taper building has 7% Cp rise at ground level ( y/H= 0.225) in the windward face, and 34% Cp fall at the middle level ( y/H= 0.475) in the side face when compared with the rectangular building. Whereas for the setback building, Cp at ground level near setback ( y/H= 0.225) has reduced to about 25% and about 6% at the middle level ( y/H= 0.475) in windward than that in the rectangle building. Also, the side faces of the setback showed a 15% drop in Cp than other buildings. In leeward face, Cp is reduced to 56% near setback at the top of the building ( y/H= 0.725). This valuation of the Cp on these buildings shows that the effect of setbacks on building reduces the pressure variation on all faces and the downstream wake vortices.

Chip-on-Beam and Hydrostatic Calibration of the Piezoresistive Coefficients on (111) Silicon

2007 ◽  
Author(s):  
Chun-Hyung Cho ◽  
Richard C. Jaeger ◽  
Jeffrey C. Suhling ◽  
M. Kaysar Rahim
Keyword(s):  
Pressure Coefficient ◽  
Experimental Methods ◽  
Temperature Dependent ◽  
Pressure Coefficients ◽  
Stress Sensors ◽  
Wide Range ◽  
Complete Set ◽  
Stress Sensing ◽  
Test Chips ◽  
P Type

Stress sensing test chips are used to investigate die stresses arising from assembly and packaging operations. The chips incorporate resistor or transistor sensing elements that are able to measure stresses via the observation of the changes in their resistivity/mobility. The piezoresistive behavior of such sensors is characterized by three piezoresistive (pi) coefficients, which are electro-mechanical material constants. Stress sensors fabricated on the surface of the (111) silicon wafers offer the advantage of being able to measure the complete stress state compared to such sensors fabricated on the (100) silicon. However, complete calibration of the three independent piezoresistive coefficients is more difficult and one approach utilizes hydrostatic measurement of the silicon “pressure” coefficients. We are interested in stress measurements over a very broad range of temperatures, and this paper present the experimental methods and results for hydrostatic measurements of the pressure coefficient of both n- and p-type silicon over a wide range of temperatures and then uses the results to provide a complete set of temperature dependent piezoresisitive coefficients for the (111) silicon.

Experimental Investigation of the Wind Pressure Distribution and Wind Interference Effects on a Typical Tall Building

2013 ◽  
Vol 639-640 ◽  
pp. 444-451 ◽  
Author(s):  
Yi Li ◽  
Q.S. Li ◽  
K.L Ju
Keyword(s):  
Pressure Distribution ◽  
Wind Tunnel Test ◽  
Side Wall ◽  
Tall Buildings ◽  
Tall Building ◽  
Wind Pressure ◽  
Shielding Effect ◽  
Interference Effects ◽  
Large Cities ◽  
Pressure Coefficients

Most tall buildings are constructed in the prosperous center of large cities, where is inevitable to be surrounded by many interfering buildings. Wind interference effects among buildings should not be neglected. Therefore, it is necessary to investigate wind interference effects on such tall buildings. Based on the wind tunnel test of rigid model of a tall building, the wind pressure distribution on the building with interfering buildings around it has been researched, the contours of the mean and fluctuate wind pressure coefficients have also been presented. It has been found that shielding effect and channeling effect are significant in the wind interference effects on building. Wind pressure coefficients on side wall and leeward wall of a upstream building may be dramatically changed in case the wake boundary of the upstream building is interfered. The conclusions might be used as reference to structural design and plan.

Wind Load Characteristics of Tall Building with Atrium

2013 ◽  
Vol 639-640 ◽  
pp. 515-522
Author(s):  
Yong Gui Li ◽  
Q.S. Li
Keyword(s):  
Wind Tunnel ◽  
Critical Role ◽  
Pressure Coefficient ◽  
Tall Building ◽  
Wind Pressure ◽  
Wind Loads ◽  
Design Guideline ◽  
Pressure Coefficients ◽  
Opening Ratio ◽  
Wind Pressures

Wind tunnel test of 1:500 rigid model of tall building with atrium was carried out. Based on the experimental results, characteristics of wind pressures on atrium facades and wind loads on the structure were investigated in detail. The results show that the formation of flow separation on the building top plays a critical role in the generation of wind pressures on the atrium facades. Meanwhile, wind pressure coefficient distributions on the atrium facades are found to be relatively uniform. Moreover, the horizontal and vertical correlations of pressure coefficient exhibit high at most locations on atrium facades. With the increasing of the opening ratio, the mean wind pressure coefficients first decreased and then stabilized, and the fluctuating wind pressure coefficients first decreased and then increased. A design guideline for the wind-resistant design of atrium facades was proposed, and the results predicted by the proposed guideline were in good agreement with those from the wind tunnel tests, indicating that the proposed guideline can be used in engineering applications. When the opening ratio is no more than 5.33%, the effect of the facade pressures within the atrium on the wind loads on the structure can be ignored. For such cases, the wind-resistant design for a tall building with atrium can refer to that of a similar shape tall building without atrium.

scholarly journals Usporedna studija predviđanja koeficijenta molekularne difuzije za polarni i nepolarni binarni plin pomoću neuronskih mreža i višestrukih linearnih regresija

2019 ◽  
Vol 68 (11-12) ◽  
pp. 573-582 ◽  
Author(s):  
Naima Melzi ◽  
Hamid Zentou ◽  
Maamar Laidi ◽  
Salah Hanini ◽  
Yamina Ammi ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Molecular Diffusion ◽  
Mean Squared Error ◽  
External Validation ◽  
Multiple Linear Regressions ◽  
Mean Squared Errors ◽  
Wide Range ◽  
Artificial Neural ◽  
Linear Regressions

In the current study, an artificial neural network (ANN) and multiple linear regressions (MLR) have been used to develop predictive models for the estimation of molecular diffusion coefficients of 1252 polar and non-polar binary gases at multiple pressures over a wide range of temperatures and substances. The quality and reliability of each method were estimated in terms of the correlation coefficient (R), mean squared errors (MSE), root mean squared error (RMSE), and in terms of external validation coefficients (Q2ext). The comparison between the artificial neural network (ANN) and the multiple linear regressions (MLR) revealed that the neural network models showed a good predicting ability with lower errors (the roots of the mean squared errors in the total database were 0.1400 for ANN1 and 0.1300 for ANN2), and (root mean squared errors in the total databases were 0.5172 for MLR1 and 0.5000 for MLR2).

scholarly journals Effect of foundation compliance on earthquake stresses in multistory buildings*

1954 ◽  
Vol 44 (4) ◽  
pp. 551-569
Author(s):  
R. G. Merritt ◽  
G. W. Housner
Keyword(s):  
Tall Buildings ◽  
Strong Motion ◽  
Analog Computer ◽  
Fundamental Period ◽  
Base Shear ◽  
Shear Forces ◽  
Multistory Buildings ◽  
Building Models ◽  
Wide Range ◽  
Building Practice

Abstract This paper shows the quantitative effect that foundation compliance has on the maximum base shear force and the fundamental period of vibration in typical tall buildings subjected to strong-motion earthquakes. A study was made of five-, ten-, and fifteen-story building models on the Electric Analog Computer, subjecting them to the ground accelerations of actual earthquakes. The base shear forces were measured, the foundation compliance of the models being changed through a very wide range. The properties specified for the building models are shown to be similar to the properties found in real buildings. The experimental results imply that the maximum base shear forces in typical buildings of five stories and higher during strong-motion earthquakes will be essentially unaffected by any degree of foundation compliance that can be expected in normal building practice. The fundamental period of typical buildings will be increased by about 10 per cent if the foundation compliance is the maximum that can be expected in standard building practice.

scholarly journals Effects of Side Ratio on Wind-Induced Pressure Distribution on Rectangular Buildings

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
J. A. Amin ◽  
A. K. Ahuja
Keyword(s):  
Pressure Distribution ◽  
Incidence Angle ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Wind Pressure ◽  
Surface Pressure Distribution ◽  
Side Ratio ◽  
Building Models ◽  
Mean Pressure ◽  
Wind Pressures

This paper presents the results of wind tunnel studies on 1 : 300 scaled-down models of rectangular buildings having the same plan area and height but different side ratios ranging from 0.25 to 4. Fluctuating values of wind pressures are measured at pressure points on all surfaces of models and mean, maximum, minimum, and r.m.s. values of pressure coefficients are evaluated. Effectiveness of the side ratios of models in changing the surface pressure distribution is assessed at wind incidence angle of 0° to 90° at an interval of 15°. Side ratio of models has considerable effects on the magnitude and distribution of wind pressure on leeward and sidewalls but it has very limited effect on windward walls at wind incidence angle of 0°. For building models with constant cross section, change in side ratio does not significantly affect the general magnitude of peak pressures and peak suctions, but rather the wind angle at which they occur. The regression equation is also proposed to predict the mean pressure coefficient on leeward wall and side wall of rectangular models having different side ratios at 0° wind incidence angle.

scholarly journals Full-Scale Measurements of Wind-Pressure Coefficients in Twin Medium-Rise Buildings

Buildings ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 63
Author(s):  
Stergiani Charisi ◽  
Thomas Thiis ◽  
Tormod Aurlien
Keyword(s):  
Probability Distribution Function ◽  
Tall Buildings ◽  
Wind Pressure ◽  
Pressure Measurements ◽  
Pressure Coefficients ◽  
Air Infiltration ◽  
Measuring Period ◽  
Building Geometry ◽  
Twin Buildings ◽  
Building Engineering

Wind pressure coefficients (Cp) are important values for building engineering applications, such as calculation of wind loads or wind-induced air infiltration and especially for tall buildings that are more susceptible to wind forces. Wind pressure coefficients are influenced by a plethora of parameters, such as building geometry, position on the façade, exposure or sheltering degree, and wind direction. On-site measurements have been performed on a twin medium-rise building complex. Differential pressure measurements have been employed in order to determine the wind pressure coefficients at various positions along the windward façades of the twin buildings. The measurements show that one building provides substantial wind shelter to its twin and the microclimatic effect is captured by the measured wind pressure coefficients. They also showed that the wind pressure coefficients vary significantly spatially along the windward façades of the medium-rise buildings. Furthermore, the pressure measurements showed that the wind pressure coefficients fluctuate significantly during the measuring period. The use of the fluctuating Cp values by means of probability distribution function (pdf) for the calculation of air infiltration has been evaluated. The results indicate that the air flows deriving using fluctuating Cp values are more accurate than the ones calculated by the conventional method of using mean Cp values.

Sign in / Sign up

Export Citation Format

Share Document