Measurement of wind-induced dynamic stresses in billboard structures | |
| Author | Moh Moh Ko |
| Call Number | AIT Thesis no.ST-18-18 |
| Subject(s) | Wind resistant design Billboards--Design and construction |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Structural Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ST-18-18 |
| Abstract | Billboard structures, which are usually used for advertising, have to resist wind load because of its large frontal area and high position above the ground. The fluctuating nature of wind velocities, pressures and forces may cause the excitation of significant resonant vibratory response in structures provided their natural frequency and damping are low enough. The resonant dynamic response can generate stresses at the base of the supporting column of billboard structure which may lead to collapse of the structure. Therefore, one of the objectives of this study is to identify the dynamic properties such as natural frequency and damping of the billboard structure. The initial damping of the billboard structure may be low enough to provoke the resonant response. However, when the flexible, dynamically wind sensitive structure like billboard is excited by wind induced forces, the motion of the structure may itself generate aerodynamic forces which counteract the structural vibration. Due to aerodynamic effect, the overall damping of the structure may be high enough to suppress the resonant response in billboard structures. Hence, dynamic responses of billboard structure to wind-induced forces are investigated in natural wind condition. A typical billboard structure located in Prachathipat, Thanyaburi District, Pathum Thani Province is selected as a case study for the full-scale measurement of wind-induced dynamic responses in natural wind condition. The strain responses at the base of the supporting column of billboard structure are measured by strain gage sensors to obtain dynamic responses of the billboard structure. After that, the dynamic properties of the billboard structure such as natural frequencies and damping ratios are identified from response time histories by performing Fast Fourier Transform and Random Decrement Techniques. Power spectral density of measured dynamic response of billboard structure is also developed to investigate the response behavior of billboard structure in natural wind condition. The results obtained from this study showed that resonant response is found to be significant in dynamic response of billboard structure to wind-induced drag force. However, damping of billboard structure to wind-induced drag force is high enough to suppress the resonant response. Since the damping of billboard structure in torsional mode is very high, the significance of resonant response in dynamic response of billboard structure to wind-induced torsion is not found. Hence, dynamic response of billboard structure to wind-induced forces are found to be dominated by quasi-static response. |
| Year | 2018 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ST-18-18 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Pennung Warnitchai; |
| Examination Committee(s) | Anwar, Naveed;Punchet Thammarak; |
| Scholarship Donor(s) | Ma Ga Manufacturing Co., Ltd. – AIT Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2018 |