Experimental and Numerical Studies on the Behaviors of Autoclaved Aerated Concrete Panels with Insulation Boards Subjected to Wind Loading

Autoclaved aerated concrete panels (AACP) are lightweight elements in civil engineering design. In this paper, experiments and numerical analyses were conducted to study the flexural behavior of an enclosure system that consisted of AACPs and a decorative plate. A full-scale test was conducted to investigate the behavior of the enclosure system under wind suction. Load–deflection curves and load–strain relationships under different wind pressures were recorded and discussed. The effects of thickness, reinforcement ratio, and strength grade on the flexural behavior of AACPs were numerically investigated. Based on the numerical results, we found that the flexural behavior of AACPs can be improved by increasing the thickness or the reinforcement ratio. A comparison of finite element and theoretical results calculated using American and Chinese design formulae was conducted, and the results indicated the existing design formulae can conservatively estimate the major mechanical indices of AACPs.

Impact of Turbulence Models of Wind Pressure on two Buildings with Atypical Cross-Sections

The article deals with the numerical analysis of the wind pressure distribution on a group of two high-rise buildings of different shape for different wind directions. The first building has the shape of a circular cylinder and the second was created by a combination of semicircles and a longitudinal member. The floor plan of the second building was similar to the letter S. The simulations were realized as 3D steady RANS. CFD results were compared with experimental measurements in the wind tunnel of the Slovak University of Technology in Bratislava. The results were processed using statistical methods such as correlation coefficient, fractional bias and fraction of data within a factor of 1.3, which determined the most suitable CFD model. The purpose of the present article was to verify the distribution of the external pressure coefficient on scale models at a scale of 1:350, which are located in the Atmospheric Surface Layer (ASL). In numerical modeling, the most important thing was to ensure similarity with the flow in the experimental Atmospheric Boundary Layer (ABL) and with the flow around the models. SST k–ω was evaluated as the most suitable turbulent model for the given type of problem. Turbulent models had a decisive influence on the overall distribution of external wind pressures on objects. The results showed that the most suitable orientation of the objects in terms of the external wind pressure coefficient is 0°, when the cylinder produced a shielding effect, with min mean cpe = −0.786. The most unfavorable wind effects were shown by the wind direction of 90° and 135° with the value min mean cpe = −1.361.

Influences of Wind Barriers on the Train Running Safety on a Highway-Railway One-Story Bridge

In this study, the influences of wind barriers on the aerodynamic characteristics of trains (e.g. a CRH2 train) on a highway-railway one-story bridge were investigated by using wind pressure measurement tests, and a reduction factor of overturning moment coefficients was analyzed for trains under wind barriers. Subsequently, based on a joint simulation employing SIMPACK and ANSYS, a wind–train–track–bridge system coupled vibration model was established, and the safety and comfort indexes of trains on the bridge were studied under different wind barrier parameters. The results show that the mean wind pressures and fluctuating wind pressures on the trains’ surface decrease generally if wind barriers are used. As a result, the dynamic responses of the trains also decrease in the whole process of crossing the bridge. Of particular note, the rate of the wheel load reductions and lateral wheel-axle forces can change from unsafe states to relative safe states due to the wind barriers. The influence of the porosity of the wind barriers on the mean wind pressures and fluctuating wind pressures on the windward sides and near the top corner surfaces of the trains are significantly greater than the influence from the height of the wind barriers. Within a certain range, decreasing the wind barrier porosities and increasing the wind barrier heights will significantly reduce the safety and comfort index values of trains on the bridge. It is found that when the porosity of the wind barrier is 40%, the optimal height of the wind barrier is determined as approximately 3.5[Formula: see text]m. At this height, the trains on the bridges are safer and run more smoothly and comfortably. Besides, through the dynamic response analysis of the wind–train–track–bridge system, it is found that the installation of wind barriers in cases with high wind speeds (30[Formula: see text]m/s) may have an adverse effect on the vertical vibration of the train–track–bridge system.

Experimental investigations of interference effects on wind pressures of tall buildings

The interference effects between two tall buildings on building surface wind pressures are studied by using wind tunnel experiments. Different breadth ratios ( B r = B interfering/ Bprincipal), depth ratios ( D r = D interfering/ Dprincipal), and relative locations of the two buildings are tested. The results show that the interference effects on mean wind pressures on the windward face and the right face are more considerable than those on the other two faces. The windward face mainly shows the shielding effect, while the right face exhibits the amplification effect. The surface interference factors ( SIF) of windward and right faces under different breadth ratios and depth ratios have clear correlation with the reference values ( B r = D r = 1.0), and a series of correlation formulas are obtained. The SIF values of the windward face in tandem arrangement and the maximum and minimum interference factors of the right face in parallel arrangement are formulated. The most prominent local peak pressure under different cases mainly concentrates in the side edge and upper edge of the windward face, the left upper corner, left lower corner, and the upper-middle part of the right face.

Experimental investigation of the aerodynamics of a large industrial building with parapet

The aerodynamic performance of a roof depends significantly on its shape and size, among other factors. For instance, large roofs of industrial low-rise buildings may behave differently compared to those of residential homes. The main objective of this study is to experimentally investigate how perimeter solid parapets can alter the flow pattern around a low-rise building with a large aspect ratio of width/height of about 7.6, the case of industrial buildings/shopping centers. Solid parapets of varied sizes are added to the roof and tested in an open-jet simulator in a comparative study to understand their impact on roof pressure coefficients. Roof pressures were measured in the laboratory for cases with and without parapets under different wind direction angles (representative of straight-line winds under open terrain conditions). The results show that using a parapet can alter wind pressures on large roofs. Parapets can modify the flow pattern around buildings and change the mean and peak pressures. The mean pressure pattern shows a reduction in the length of the separation bubble due to the parapet. The parapet of 14% of the building’s roof height is the most efficient at reducing mean and peak pressures compared to other parapet heights.

A Conditional Simulation Method for Predicting Wind Pressure Fields of Large-Span Spatial Structures

Wind load is among the control loads for large-span spatial structures. Wind tunnel test is one of the commonly used methods for measuring wind pressure fields of different kinds of structures. However, due to the limited wind pressure data obtained from wind tunnel testing, it is quite meaningful to employ the limited measured data to predict the unknown wind pressure at target points. Considering the complexity of wind pressure fields of large-span spatial structures, a simplified nonparametric method based on conditional simulation is proposed to predict the unknown pressures using the existing data. The Karhunen–Loève (KL for short) expansion is employed to represent wind pressure random variants as eigenfunctions of the covariance operator. To reduce the variant dimensionality, the nearest neighboring estimator is given for the transition distribution of the KL expansion. The targeted wind pressure fields are obtained by expanding the Fourier basis of the eigenfunction and estimating its expansion coefficients. The proposed method is applied to estimate wind pressures on a gable roof building. The relevant parameters of the wind pressure field are obtained, and the results compare well with those from wind tunnel testing, with higher efficiency. The proposed method effectively reduces the dimensionality of the predicted wind pressures, with reduced errors, higher accuracy, and increased efficiency.