Wind-induced Dynamic Response of Large Billboard Structures (original) (raw)

Analysis of Wind Load Factors and Stability on Sensitive Structures

IRJET, 2022

The roofs of low-rise structures are usually flat, pitched / gabled, hipped, or curved. Structures with curved roof are being constructed to achieve large unobstructed spans like entertainment centres, exhibition centres, sports arenas, airport hangers, etc. which are essential for various functional requirements. These structures are generally constructed either at ground level or at an elevated level. Wind loads are considered to be one of the most important load criteria for the structural design of such structures. The aerodynamic behaviour and wind induced pressures over the curved roofs are being affected by major factors such as inflow characteristics such as mean velocity and turbulence intensity profiles, Reynolds number, surface roughness, angle of wind incidence, neighboring structures, size of tributary area and geometric proportions such as rise to span ratio, wall height to span ratio, length to span ratio and wall height to rise ratio. Based on the wind induced pressure information, database assisted design and equivalent static wind loading are used to establish wind loading for their structural design. Studies on the characteristics of wind pressure over curved roofs were reported over the last three decades. Based on the earlier studies, the rise to span ratio is observed to be significantly affecting the wind pressure on curved roofs. The side wall height to span ratio and building length to span ratio are the two other geometric proportions, which also influence the wind induced pressure on curved roofs, as reported in the literature. Further, most of the studies reported in the literature were conducted under any one type of flow conditions, viz. uniform flow, open and suburban terrain conditions.

Dynamic response under wind of a cylindrical air-supported structure

Journal of Wind Engineering and Industrial Aerodynamics, 1983

The problem of simulation of dynamic behaviour under wind of a single skin cylindrical air-supported structure is presented in the present work. The large geometric non-linearity of the structural system and the dependance of the loading on the final shape are the most difficult aspects of the problem. In a previous paper (ref.l) a "shooting type" method has been proposed and applied to the static case. The method overcomes the above mentioned difficulties through a trial and error procedure, imparing equilibrium successively at the various joints of a discretized membrane. The above method is here modified and applied to the dynamic case, imposing dynamic equilibrium in the time domain at every joint of the air-supported membrane. Modifications are needed in order to take into account of inertia forces not normal to the final shape. The wind loading function is simulated in the time domain, using the method proposed in ref. 8 by Shinozuka and Jan. The njethod involving dynamic equilibrium step by step in the time domain consists of an iterative procedure with a prediction of acceleration and velocity at the end of a timestep in terms of the kinematic quantities at the beginning of the time step as well as in terms of the displacement corresponding to the time interval. Some results are given for a numerical example of an air-supported structure. A satisfactory stability and convergence of the method has been obtained. I. INTRODUCTION Air-supported structures are one of the most sensitive type of low-rise buildings. Wind is the most important design action for this type of structure and has been the cause of numerous accidents and structural failures which have occurred in recent years. The lack of theoretical knowledge of wind effects, especially of dynamic effects, together with poor quality of the material and inaccurate building details, have lead to a series of accidents in the 70 s, that cast grave doubts on the use of air-supported structures.

A numerical study of wind-induced tower vibrations

Computers & Structures, 1987

The application of the finite element method for the analysis of wind-induced tower vibrations is presented and discussed. In this study simulated wind forcing functions were applied to a 3-D model of an existing illumination tower, and its response was studied under various loading conditions. The obtained numerical results are compared with experimental data for evaluating the accuracy of this approach. NOTATION area on which wind forces act parameter for relating wind velocity with height shape factor, or force factor damping matrix drag coefhcient lift coefficient dimension of body normal to wind flow tower diameter elastic modulus force structural response frequency vortex shedding frequency stitTness matrix mass matrix forcing function vector dynamic head of wind Reynolds number Strouhal number time wind speed kinematic viscosity of air acceleration, velocity and displacement vectors, respectively elevation of points at which wind speed is measured, or computed mass density of air vortex shedding circular frequency

Simulation of Wind Loading Action on Hanging Structures Literature Survey

The hanging structures are the progressive kind of space structures. A great functionality of these constructions consists in possibility of very big surfaces roofing with relatively restricted number of supports. Hanging roofs serves as hall roofs (amphitheatres, sports, exhibitions), also as airports, hangars etc. One of the most important conditions of their calculations is proper determination of changeable in time loads, among them the decisive role plays the wind loading. Wind loads are applied on a structure as the result of complex interaction between wind and the structure itself. This interaction can be classified by aerodynamic and aeroelastic effects . The present paper gives the literature review of the wind loading determining for hanging roofings.

Torsional and across-wind response of high-rise buildings

In the present paper the across-wind and torsional responses of tall buildings exposed to turbulent wind are analyzed. Three models with different cross sections have been tested to obtain measurements of the pressure field. Using the wind tunnel pressure data, numerical analyses for the evaluation of the across-wind and torsional responses have been performed. In particular, both the direct integration of the equations of motion on an equivalent dynamic system and the response analysis based on random vibration theory were carried out. The results were compared with each other and with the results of the most reliable procedures suggested by the current international codes addressing across-wind and torsional responses. The comparison allowed to investigate the safety margins provided by different methods and to highlight the advantages and disadvantages inherent in each procedure

Impact on Structural Behavior Due to Installation of Billboard

Jurnal Teknologi

Installation of billboards on various structures adjacent to busy roads has become common practice as they provide high economic to the local municipal corporation or private business organisations. Till recent, design of billboards and its installation on a structure was of less importance, but recent large wind cyclones had led to the collapse of billboards and structural cracks. This incident has raised doubts in structural engineering community for the resistance of buildings with billboards during earthquakes. In this study, an existing building with the recent installation of a billboard has considered, and dynamic analysis is carried out for three different ground motions viz. El Centro earthquake, Loma Prieta earthquake and Uttarkashi earthquake for understanding the change in its behaviour with and without billboard. The structure has shown an increment of response due to the installation of a billboard during earthquakes.

Dynamic torsional behavior of tall building under wind loads using CFD approach

The dynamic torsional behavior of rectangular tall buildings under wind loads has been investigated using wind tunnel tests. It has been found that one of the main factors influencing the dynamic torsional behavior of tall buildings is the dynamic characteristics of the wind such as turbulence and wake excitation. In addition to that, the dynamic characteristics of the building itself influence the torsional behavior. The Ansys CFX10 has been used to analyze the flow over building model with the wind speed profile and turbulence profile generated from AS 1170.2 for the suburban terrain category. Different aspect ratios of rectangular tall buildings have been studies from square to slab type structure. The dynamic torsional moment has been analyzed from pressure distribution on surrounding surfaces of the rigid models of tall buildings. The torsional moments are normalized in coefficient form with the maximum projected width and the maximum projected area of the building. The numerical results are being comparable with the experimental results from Cheung and Melbourne .