Analysis of Billboards Signs Collapse Due to Intensive Wind of Hurricane Maria

Abstract

In Structural Analysis the collapse of different structures always will depend on factors such as the loads, dimensions and material used for building the structure. Billboards signs are commonly used by the outdoor media companies to deliver a message to the public and society. In Puerto Rico, this types of structures are subjected to high-intensity winds due to the hurricanes phenomena that take place on our island. Highintensity winds could cause severe damage to the sign structure causing sudden collapse. A few months ago a category four hurricane called “Maria” hit Puerto Rico and different structure of this type collapsed on the whole island due to the intense wind loads they were subjected. In this project, different cases of billboard failures were identified, and field visits were developed to perform a visual inspection, take measurements, and perform a general assessment of the failure, and correlate damages. A local buckling and plastic yielding type of failure was noted at the lower ends of poles supporting the sign's structure. This took place immediately above ground level where the major concentration of stress due to the wind force occurred. One of the cases, located in the Municipality of Bayamon, was selected to conduct a simulated failure analysis that would be capable of reproducing the situation found, thus allowing to estimate the wind speeds at the moment of failure. The Finite Element Analysis (FEA) software SAP200 R19 was used to perform an elastic buckling analysis to find the critical load factor and the bucking modal shape, and determine which velocity of wind produced the critical condition that may produce caused the buckling failure. Then a full static nonlinear analysis (pushover analysis) considering material nonlinearity and geometric P-Delta effects was performed, with the same objectives. Key Terms - Billboard Signs, Buckling Load, Critical load, Wind Forces.