Wind Incidence Angle Research Articles

Wind Effects on Rectangular and Triaxial Symmetrical Tall Building Having Equal Area and Height

The study aims to investigate wind effects on the equal area and the same height building model having the plan cross‐sectional shape in the form of regular and irregular shape bulidings. The ratio of modification in the cross‐sectional shape is kept same for regular and irregular shaped models because limited studies are available for such type of comparison. The responses of the structure to resist the wind load is increased by applying these modifications in the corner configuration such as corner cut, chamfer, and fillet in the plan shape of the structure. The numerical study is performed using ANSYS CFX and wind incidence angle varies in the range of 0° to 180° at the interval of 15°. The results of velocity and pressure distribution are presented in the form of pressure contours and wind force coefficients for all four‐building models which are presented in the form of a graph. The comparison of numerical simulation results on two models are compared with the different international standards and with the experimental results. The regular shape with a corner cut and a “Y”‐shaped structure with a fillet corner model performed the best among all models for resisting overall wind force. The results of pressure distribution of all four models are presented in the form of pressure contours for 0° and 90° wind angles.

Aerodynamic mitigation by corner modification on square model under wind loads employing CFD and wind tunnel

This paper explores a recent application of the computational fluid dynamics technique “CFD” for wind analysis and its comparisons with the conventional wind tunnel experimentations. This study is centered on the wind response of square and corner cut-shaped building models and its optimization caused by the variation of the wind incidence angle. Extensive rigid model experiments of two building models of length scale 1:100 have been performed in the boundary layer wind tunnel. The numerical analysis has been carried out with the standard k-ε turbulence model to evaluate the force coefficients, base moments, power spectra, external surface pressure coefficients, and flow field characteristics of the models with variable wind angles of incidence. The comparisons between experimental results and CFD analysis suggest the computational approach's viability in wind analysis of tall structures efficiently and accurately. A case study of aerodynamic mitigation by corner cut suggests minor modification techniques performance, efficiency, and limitations.

Numerical Study of Wind induced Pressures on Irregular Plan Shapes

Purpose: This paper presents the numerical examination of wind pressure distributions on irregular plan shape building models over wind incidence angles of 0° and 180°. The purpose of this study is to investigate the effect of irregular building form, projection ratios, distances from the re-entrant corner, the building height and wind incidence angles on the wind flow and wind pressure distributions at all surfaces of the buildings.Design/Methodology/Approach: Two L-shaped and two T-shaped building models having the same plan area and height but having different projections in plan were analyzed by the application of Computational Fluid Dynamics (CFD) package of ANSYS. With this purpose, wind pressure distributions on and around various irregular plan shaped buildings are analysed for the same height level.Findings: As a result of the studies, it has been observed that the plan shape, projection ratios, distances from the re-entrant corner, significantly affect the wind characteristics on building.Research Limitations: In recent years, numerical approaches based on computational fluid dynamics (CFD) simulations are being commonly used engineers and architects for various wind studies such as determining wind loads on buildings and investigating wind flows in built area. Model dimensions were reduced to 1/100 scale to save computing time.Practical Implications: Understanding the behavior of the building under the wind load will increase the solution oriented approach to the problems at the initial part of the design stage.Social Implications: The study supports occupant comfort by making it easier to perceive the design component wind in the architectural sense.Originality/Value: Wind is a significant architectural design component. However, there are very few studies on wind behavior of buildings in the architectural field. This is often observed as an engineering problem. On the contrary, it is primarily an architectural design piece to be perceived. Therefore, understanding the behavior of buildings under wind loads is vital to develop problem-oriented solutions at every stage of the design phase. Projections in plan with different wind angle and distances from the re-entrant corner’s effect on pressure coefficients were not be studied comprehensively. Key Words: Building form, building dimensions, projections, mean wind pressure coefficient, computational fluid dynamics (CFD

Fluid-structure interaction analysis of a lightweight sandwich composite structure for solar central receiver heliostats

Central tower concentrating solar power systems are moving to the forefront to become the technology of choice for generating renewable electricity, but their widespread implementation is limited by cost. Heliostats contribute almost 50% to the plant’s cost and are thus the most significant element in central tower systems. For both large and small-area heliostats, the drive elements demonstrate the largest cost element in these systems. While large-area heliostats (>100 m2) have proven offer the best economy compared to other sizes, they require high-torque drives due to the heavy steel-based support structure. Heliostat costs could be reduced by decreasing the support structure’s weight, avoiding large drive units and reducing energy consumption. However, the structure must be able to cope with the aerodynamic loads imposed upon them during operation. Although honeycomb sandwich composites have been widely used where high structural rigidity and low weight are desired, there is an absence of studies that rigorously investigated their suitability as the structure for heliostat mirror. Here, a fluid-structure interaction study investigated, for several loading conditions at various tilt and wind incidence angles, the aero-structural behavior characteristics of honeycomb sandwich composites used as a heliostat support structure. The honeycomb sandwich panel showed markedly different behavior characteristics at various operational conditions. The effect of tilt orientation on the sandwich panel’s maximum deflection and stresses became more pronounced as wind velocity increased above 10 m/s, and increasing wind incidence angle reduced their magnitudes at different rates. The supporting components and torque tube had a noticeable wind-shielding effect, causing pronounced changes in the deflection and stresses experienced by the heliostat. The worst operational condition was at a tilt angle of 30° with wind flow of 20 m/s at 0° to the heliostat surface. However, the heliostat maintained its structural integrity according to relevant optical and material failure standards.

Experimental study on mitigating extreme roof suctions by passive vortex generators

High wind suction always occurs at the edges and corners of large-span low-rise flat roofs, which can lead to severe damage to roof elements and even to the overall destruction of the roof. The passive vortex generator (PVG), a new device which can generate streamwise vortices, is proposed to mitigate the extreme wind suction on a low-rise large-span flat roof. Wind tunnel tests were conducted to investigate the control effect of PVGs, and parametric analysis was performed, with parameters including the height, length, opening angle, tilt angle and interval of PVGs. The maximum reduction of peak wind pressure under the worst wind incident angle with PVGs reaches 74%, and they show excellent control effects at all wind incident angles. The recommended parameters of PVGs are also provided for engineering practice. Spectrum analysis and the structure of the conical vortices show that the streamwise vortices generated by PVGs which mixed into the conical vortices and can distort or destroy the conical vortices, and then alter the position of conical vortices axis and reduce the reattachment range. Meanwhile, the high frequency fluctuation is increased and the low frequency fluctuation is reduced accordingly.

Incident wind angle and topographic steering through excavated foredune notches

Artificial foredune ‘notching’ aims to increase sand transport between the beach and backdune environments to enhance biodiversity and increase foredune resilience. Recent research has examined the morphodynamics of dunes in the lee of notches, however the conditions that favour sand transport through the notches, and the associated processes of topographic steering, flow acceleration and deceleration, have not been systematically examined. It is important to examine the relationship between these processes because on most temperate coasts regional winds cross shorelines at oblique angles.This study combines field-based experiments and Computational Fluid Dynamics (CFD) modelling to examine the relationship between the relative incident wind approach angle, topographic steering and flow acceleration through an excavated foredune notch located at St Kilda, New Zealand. Secondary wind speed and direction is recorded in the notch by 12 ultrasonic anemometers and compared with incident wind conditions measured at 6.5 m above the foredune crest. Field data is used to validate the CFD simulations, which is used to examine the flow dynamics at a larger spatial scale, across the beach, as well as through the notch.Wind speeds inside the notch are strongly correlated with incident wind angles ranging from −6° to 77° relative to notch orientation. Wind flow realignment to notch orientation, compression and acceleration through the notch occurs when the relative incident wind angle is less than 27° for a notch oriented 77° to the shoreline. Wind flow separation and deceleration occurs when the relative angle is greater than 27°. An empirical model relating incident wind speed, direction and notch activation (i.e. when sand transport occurs) is developed. The threshold of incident wind speed for notch activation increases when the relative wind angle increases, and vice versa.

Wind Induced Pressure Variation on High-rise Geometrically Modified Building having Interference through CFD Simulation

The wind different forms i.e. cyclones, hurricanes, storms, tornados, etc., loads various structures which come in their way. To minimize the wind effects, different techniques have been used and geometrical modification is one of them. In this study, the pressure variation on a geometrically modified high-rise corner-cut building having interference has been evaluated. The study is carried out using ANSYS FLUENT in which CFD simulation is carried out for the different models at different wind incidence angles viz. 0°, 45°, and 90°. Two building models are used in this study, one is high rise Corner-cut building, which is called the principal or primary building. The other is a high-rise rectangular building, which is called interfering or secondary building. The results obtained in case of interference are then compared to that of an isolated corner-cut building. In general, from the present investigation, it is noticed that the suction effect increases due to the interference effect. When wind strikes obliquely the effect of interference is relatively lower.

The Plasma Environment Surrounding the Reiner Gamma Magnetic Anomaly

AbstractReiner Gamma is a prime target for low‐orbiting spacecraft or even surface‐landed missions in the near future. The region hosts a prominent lunar swirl that is co‐located with a strong and well‐structured magnetic anomaly. We simulate and discuss Reiner Gamma's near‐surface plasma environment at different altitudes above the lunar surface using the fully kinetic particle‐in‐cell code iPIC3D. The input magnetic field model is based on orbital‐altitude observations from the Kaguya and Lunar Prospector missions. We develop eight simulation cases, representing the distinct plasma regimes. Reiner Gamma is exposed to along a typical orbit, including different solar wind incidence angles and the magnetosheath crossing. We show that the plasma environment is vastly different at different altitudes and depends critically on the upstream plasma parameters, consistent with the predictions of the solar wind standoff model. Our work helps to define measurement requirements for a possible future low‐orbiting or lander mission to the Reiner Gamma area or similarly magnetized regions of the lunar surface.

Wind flow on and around U-shaped buildings

PurposeThis paper presents the numerical examination of wind pressure distributions on U-plan shaped buildings having four different depth ratios (DR) as 0.5, 1, 2 and 4 over wind incidence angle (WIA) of 0°. The purpose of this study is to investigate the effect of irregular building form, DRs, distances from the reentrant corner, wind velocity values on and around wind pressure distributions of the buildings. With this aim, ANSYS Fluent 20.0 Computational Fluid Dynamics (CFD) program is used for the analysis.Design/methodology/approachFour U-shaped buildings having the same height, width and wing length but having different DR in plan were analyzed by the application of CFD package of ANSYS 20. With this purpose, wind pressure distributions on and around U-plan shaped buildings were analyzed for the wind velocity values of 2 and 5 m/s over WIA of 0°. Comprehensive results were obtained from the analyses.FindingsWhile the change in the DR values did not create a significant change in positive pressure coefficients on A and E surfaces, negative pressure values increased as the DR decreased. The negative pressure coefficients observed on the A and E surfaces become higher than the positive pressure coefficients with the decrease in the DR. On contrary to that condition, with the decrease in the DR, G surfaces take higher positive pressure coefficients than the negative pressure coefficients. The reason for this is that the DR decreases and negative pressure values on G surface significantly decrease. The effect of the DR on the pressure coefficients is remarkable on B and D surfaces. The negative pressure coefficients on the B and D surfaces tend to increase as the DR decreases.Research limitations/implicationsThis study focused on DRs and wind velocity values effect on pressure coefficients to limit variables. Different building wing dimensions did not take into account.Originality/valueAlthough there are a number of studies related to wind behavior of irregular plan shaped buildings, irregular building forms have not been extensively investigated parametrically, especially in terms of the effect of DR on wind pressures. This study is therefore designed to fill this gap by analyzing impacts of various parameters like building shape with various DRs, WIA and wind velocity values on wind pressure distributions and velocity distributions on and around the building.

Effect of Natural Wind on the Transiting Test for Measuring the Aerodynamic Coefficients of Structures

The aerodynamic coefficients transiting test is a new method for measuring the structural aerodynamic coefficients using the wind generated by a moving vehicle. However, the effect and correction of natural wind on the transiting test has not been studied. Hence, in this study, the investigation of the aerodynamic force and pressure measurements on a special triangular prism model is simulated through the transiting test under different natural wind conditions for 30° and 90° angles of wind incidence. Force and pressure measurement results in the transiting test are used to describe and explain the effect of natural wind in the range of 0–3.0 m/s on the aerodynamic coefficients of the symmetric triangular prism qualitatively and quantitatively. The results show that the driving wind field of the vehicle, aerodynamic force coefficient, and aerodynamic pressure coefficient are significantly influenced by strong natural wind greater than 1.71 m/s, which must be considered and so it is recommended that the structure aerodynamic coefficients transiting test should be conducted under the condition that the natural wind is less than 1.71 m/s. In addition, the method of two-direction round-trip measurement is proposed to modify the effect of natural wind on transiting tests.

Effects of wind direction and building array arrangement on airflow and contaminant distributions in the central space of buildings

Buildings are physical obstacles that diminish the benefits of wind by creating turbulence and reducing airflow velocities in urban settings. Particularly in the inner garden or amenities situated at the pedestrian level in the central space of a group of buildings, the efficiency of pollutant dispersion determines air quality and outdoor health. In this study, the effects of incident wind angles on wind velocity and pollutant distribution inside the central space of two building arrays arranged in ‘L’ and ‘U’ shapes were examined using computational fluid dynamics simulations. The ‘L’-shaped array performed better than the ‘U’-shaped array by forming a smaller low-wind-velocity (LWV) zone in the central space of the buildings (34.9%–76.11 % of the total space). The ‘L’-shaped array performed best at an incident wind angle of 225°, in which the LWV zone covered only 34.52 % of the central space. A 90° incident angle produced the largest LWV zone (81.80 %) for the ‘U’-shaped array. The ‘L’-shaped array generally distributed pollutants better than the ‘U’-shaped array. However, the ‘U’-shaped array with a 180° wind angle had a smaller high pollutant concentration area than the ‘L’-shaped array with a wind angle of 225° (Kc > 218.5 covering only 0.37 %). The worst vertical dispersion corresponded to a 135° wind angle for the ‘L’-shaped array, which recorded the highest Kc at the mid-level of the building. In conclusion, the appropriate selection of building array designs and their orientations allows for the most effective use of wind flow to enhance ventilation and pollutant dispersion.

Vehicle–bridge interaction and driving accident risks under skew winds

This paper proposes a new methodology to simulate wind fields that are non-orthogonal to the structure and to the traffic direction, and it presents the first wind–vehicle–bridge interaction (W-VBI) analysis framework to account for skew wind effects on the driving safety. The three-directional skew wind fields that are generated match well the target frequency content and correlation properties along the deck. The W-VBI methodology is applied to the study of vehicles crossing a long bridge for a wide range of wind incidence angles. It is observed that even though purely cross-winds increase the vehicle–bridge interaction, skew headwinds are more likely to cause driving accidents. • A new method to simulate wind that is non-orthogonal to the structure is proposed. • The first wind–vehicle–bridge interaction method with skew winds is developed. • Purely cross-winds maximise the bridge response and its interaction with vehicles. • Headwinds are significantly more dangerous for the vehicle safety than cross-winds.

Comparison of Downdraught and Up Draft Passive Air Conduction Systems (PACS) in a Winery Building

A huge portion of energy consumption in buildings comes from heating, ventilation, and air conditioning. Numerous previous works assessed the potential of natural ventilation compared to mechanical ventilation and proved their justification on the field. Nevertheless, it is a major difficulty to collect enough information from the literature to make decisions between different natural ventilation solutions with a given situation and boundary conditions. The current study tests the passive air conduction system (PACS) variations in the design phase of a medium-sized new winery’s cellar and production hall in Villány, Hungary. A computational fluid dynamics simulation based comparative analysis enabled to determine the differences in updraft (UD) and downdraught (DD) PACS, whereby the latter was found to be more efficient. While the DD PACS performed an air change range of 1.02 h−1 to 5.98 h−1, the UD PACS delivered −0.25 h−1 to 12.82 h−1 air change rate. The ventilation performance of the DD version possessed lower amplitudes, but the distribution was more balanced under different wind incident angles, thus this version was chosen for construction. It could be concluded that the DD PACS provides a more general applicability for natural ventilation in moderate climates and in small to medium scale industry hall domains with one in- and one outlet.

Effects of different wind directions on ventilation of surrounding areas of two generic building configurations in Hong Kong

This study investigated effects of incident wind angles on wind velocity distributions in wakes of two generic building configurations, namely, ‘T’- and ‘+’-shaped, and the air pressure distributions along their leeward walls by using computational fluid dynamics simulations. Results show that when the wind approaches laterally (90°) (vs. when the wind is direct (0°)), the downwind length and maximum bilateral width of the low-wind velocity zone in the wake of ‘T’-shaped building decrease by 11.5% and 37.9%, respectively. When the incident wind is oblique (45°) (vs. when it is direct), the length and width of this low-wind velocity zone in the wake of ‘+’-shaped building decrease by 15.0% and 30.9%, respectively. Furthermore, results show that the air pressure on the leeward walls of the ‘T’- and ‘+’-shaped buildings gradually decreases along with the building height. The resulting low-wind conditions on upper floors of buildings reduce the fresh air intake of their leeward units utilizing natural ventilation. It is particularly apparent in the case of direct approaching wind. Thus, the appropriate selection of building configurations and their orientations allows for the most effective use of wind to enhance ventilation in indoor and urban environments.

Aeroelastic model design and sensitivity analysis of a complicated steel truss arch tower to skew incident winds based on wind tunnel tests

An aeroelastic model design method of a complicated steel truss arch tower was proposed and the response features subjected to skew incident wind forces were presented via experimental approach. At the geometric scaling of 1:40, the bars of aeroelastic model were designed and manufactured with scaled appearance, of which the rigidities are scaled based on the classification grouping to the dimensions and weights are compensated. The buckling analysis and checking calculation of members’ slenderness ratio were carried out. Wind tunnel tests on the completed stage and two key construction stages were conducted with various skew incident angles. Otherwise, the sensitivity coefficient of the y directional extreme displacement for the completed tower in turbulent flow was analyzed. The results show that the wind load in y direction has much more effect on the structure and the wind induced responses meet the design requirements. The maximum y directional extreme displacement at the reference wind speed appears within the range of wind incident angles 0°~30°. The decrease trend of the y directional extreme displacement of the completed tower in turbulent flow in the wind incident angle range of 30°~80° is bigger than that in other angles. • The aeroelastic model design method of a complicated steel truss arch tower with multi-end constraints has been proposed. • The buckling analysis and checking calculation of members’ slenderness ratio for the model have been carried out. • The complicated aeroelastic model has been manufactured and validated. • The dimensionless sensitivity coefficient has been used to analyze the response sensitivity of the model to skew wind.

Aerodynamic Characteristics of Coupled Twin Circular Bridge Hangers with Near Wake Interference

Much work has been devoted to the investigation and understanding of the flow-induced vibrations of twin cylinders vibrating individually (e.g., vortex-induced vibration and wake-induced galloping), but little has been devoted to coupled twin cylinders with synchronous galloping. The primary objective of this work is to investigate the aerodynamic forcing characteristics of coupled twin cylinders in cross flow and explore their effects on synchronous galloping. Pressure measurements were performed on a stationary section model of twin cylinders with various cylinder center-to-center distances from 2.5 to 11 diameters. Pressure distributions, reduced frequencies and total aerodynamic forces of the cylinders are analyzed. The results show that the flow around twin cylinders shows two typical patterns with different spacing, and the critical spacing for the two patterns at wind incidence angles of 0° and 9° is in the range of 3.8D~4.3D and 3.5D~3.8D, respectively. For cylinder spacings below the critical value, vortex shedding of the upstream cylinder is suppressed by the downstream cylinder. In particular, at wind incidence angles of 9°, the wake flow of the upstream cylinder flows rapidly near the top edge and impacts on the inlet edge of the downstream cylinder, which causes a negative and positive pressure region, respectively. As a result, the total lift force of twin cylinders comes to a peak while the total drag force jumps to a higher value. Moreover, there is a sharp drop of total lift coefficient for α = 9–12°, indicating the potential galloping instability. Finally, numerical simulations were performed for the visualization of the two flow patterns.

Study on wind flow around a pentagon plan shape tall building using CFD

Multi-storey buildings are emerging because of the lack in land availability within urban areas. Mostly, tall buildings are irregular in plan and more complex to wind action. In the present scenario, it is important to study the wind structure interaction for irregular plan shape tall buildings. This paper is focused on understanding the behaviour of pentagon plan shape building under wind load at different wind incident angles 0°, 45°, 90°, 135° and 180°. The wind behaviour is studied using Computational Fluid Dynamics (CFD) and turbulence model k- is used for external flow simulation around the tall buildings. The building models are scaled in the ratio 1:300 and wind velocity at inlet is scaled in the ratio 1:5 respectively. From the results, external pressure coefficient on various faces of the buildings, drag coefficient and lift coefficients are determined for pentagon shape building. The maximum positive external pressure coefficient (Cp) is 0.446 had occurred in Face A at 180° wind incident angle and the maximum value of the negative external pressure coefficient (Cp) is 0.388 had occurred in Face D at 135° wind incident angle.

Heat removal and hybrid ventilation characteristics of a vertical dry storage cask for spent nuclear fuel

Computational fluid dynamics (CFD) was used in this study to numerically simulate the heat removal and hybrid ventilation characteristics of a vertical dry storage cask for spent nuclear fuel. The parameters included a Grashof number of 1.0x1011, an approaching wind incidence angle of 0° or 45°, and a Reynolds number (Re) of 2.7×104-8.0×105 (Gr/Re2=0.15-137). As shown by the results, the buoyant airflow dominated the heat removal capability of the cask at low Re (2.7×104). When the Re was increased to 5.3×104-1.3×105, the wind-induced channel airflow compromised the buoyant airflow, thus reducing the heat removal capacity of the cask. When the Re was⩾2.7×105, the wind-induced airflow dominated.

Wind-driven ventilation of Double Skin Façades with vertical openings: Effects of opening configurations

Insufficient airflow in the cavity of Double Skin façade (DSF) systems has resulted in the overheating risk of the cavity and the resulting reduction in thermal performance in cooling dominant climates. Previous research has focused more on buoyancy-driven natural ventilation, and there is a lack of research on utilising wind-driven ventilation in the cavity as a dominant natural force for the heat dispersion from the cavity. Additionally, geometrical features of the cavity and wind direction as influential factors on wind-induced airflow have not been addressed in DSF studies. This paper presents a detailed evaluation of the impact of opening configurations on the ventilation performance of an integrated tall building with DSF with respect to four wind orientations (0°, 30°, 60°, and 90°) to the facade. The evaluation is based on three ventilation performance indicators: (i) induced airflow rate, (ii) wind speed ratio, and (iii) airflow distribution across the cavity length. High-resolution 3D steady RANS CFD simulations of cavity ventilation were performed for a range of sizes of the DSF cavity. The CFD simulations were validated against wind-tunnel measurements. The results show that the ratio between the areas of the front and lateral openings is a critical factor for improving the ventilation in the cavity at the wind incident angle 0° < ϴ < 30°. As wind direction increases to 60° and 90°, cavity size tends to be of the highest importance. Employing three front openings on the external skin of DSF (M3) can increase the efficacy of the system in a broader range of wind direction and cavity size.

Estimation of wind pressure coefficients on multi-building configurations using data-driven approach

Wind load acting on a standalone structure is different from that acting on a similar structure which is surrounded by other structures in close proximity. The presence of other structures in the surrounding can change the wind flow regime around the principal structure and thus causing variation in wind loads compared to a standalone case. This variation on wind loads termed as interference effect depends on several factors like terrain category, geometry of the structure, orientation, wind incident angle, interfering distances etc., In the present study, a three building configuration is considered and the mean pressure coefficients on each face of principle building are determined in presence of two interfering buildings. Generally, wind loads on interfering buildings are determined from wind tunnel experiments. Computational fluid dynamic studies are being increasingly used to determine the wind loads recently. Whereas, wind tunnel tests are very expensive, the CFD simulation requires high computational cost and time. In this scenario, Artificial Neural Network (ANN) technique and Support Vector Regression (SVR) can be explored as alternative tools to study wind loads on structures. The present study uses these data-driven approaches to predict mean pressure coefficients on each face of principle building. Three typical arrangements of three building configuration viz. L shape, V shape and mirror of L shape arrangement are considered with varying interfering distances and wind incidence angles. Mean pressure coefficients (Cp mean) are predicted for 45 degrees wind incidence angle through ANN and SVR. Further, the critical faces of principal building, critical interfering distances and building arrangement which are more prone to wind loads are identified through this study. Among three types of building arrangements considered, a maximum of 3.9 times reduction in Cp mean values are noticed under Case B (V shape) building arrangement with 2.5B interfering distance. Effect of interfering distance and building arrangement on suction pressure on building faces has also been studied. Accordingly, Case C (mirror of L shape) building arrangement at a wind angle of 45° shows less suction pressure. Through this study, it was also observed that the increase of interfering distance may increase the suction pressure for all the cases of building configurations considered.