Study of Load Effects on a Dome Due to Fluctuating Wind Loads

The present study attempts to compare three contemporary techniques available to estimate peak load effects on structures from limited pressure histories, obtained from Wind Tunnel tests. A wind tunnel test was performed to study fluctuating wind loads on smooth and rough surface dome. The dome model was instrumented with 85 pressure taps. Pressure coefficient history at each tap location was obtained from the wind tunnel test. A Finite Element Model of the dome was created using structural analysis software RISA 3D at the Computer Laboratory of Wind Science and Engineering Research Center of Texas tech University. Structural analysis of the dome was performed for unit load at each of the 85 pressure tap locations and the load effects (displacement and moment) at the apex and stagnation point of the dome were calculated Thus the influence coefficients for load effects at apex and stagnation point were obtained for each of the 85 pressure taps. The influence coefficients were used to estimate the peak load effect coefficients at apex and stagnation point of the dome using three methods, viz., Actual Analysis, Quasi Steady theory and Covariance Integration method. The peak load effect coefficients obtained from the three methods were compared with each other. Load Response Correlation (LRC) technique was used to estimate the extreme pressure coefficient distributions on the surface of the dome, which are expected to cause peak load effects at the apex and stagnation point of the dome. The LRC extreme pressure coefficient distributions were calculated for two values of 'g~ one, same as that used for Covariance Integration method and the other, estimated from the peak load effect coefficients obtained from Actual Analysis. The LRC extreme pressure coefficients were compared with the actual pressure coefficients causing peak load effect coefficients in Actual Analysis. The pressure coefficient distributions obtained from LRC for two values of 'g ', were then applied on the surface of the dome and structural analysis of the dome was performed to calculate the peak load effect coefficients at the apex and stagnation point of the dome. This was done to confirm the peak load effect coefficients obtained from Actual Analysis and Covariance Integration method. All of the above calculations were performed for both smooth and rough surface dome. The peak load effect coefficients from the three methods, for smooth and rough surface dome were compared to understand the effect of surface finish of the dome on peak load effect coefficients.