# Wind Vulnerability of Flexible Outdoor Single-Post Billboards
## 6 Conclusions  
A methodology for determining the safety level of flexible single-post billboards is presented. Fluid and mechanical models were proposed and maximum values of internal forces and displacements in the most critical positions were obtained using linear elastic analysis. The maximum capacity of the billboard was determined by non-linear analysis and compared with those determined from the linear analysis. Limit state functions were determined according to the places most susceptible to damage. A reliability analysis wasperformed using the proposed probabilistic parameters of the random variables. Several wind speeds, bias factors and coefficients of variation were recommended. With the proposed methodology the following conclusions can be drawn:  
1. Determined gust load factors (GLF) for all the evaluated reference wind speeds had values higher than 2.0 and with an increment rate of the wind speed. This indicates high dynamic interaction between wind and the billboard. 2. Modal analysis points out that the billboard has a similar first period in the directions parallel and perpendicular to the panel, resulting in 0.96 s and 0.95 s, respectively. This indicates a high flexible structure susceptible to wind dynamic interaction. 3. Negligible differences were noted between internal forces for head-on and north eastbound wind directions with higher values at 45\({}^{\circ}\) for all evaluated wind speeds. Therefore, reliability analyses were performed using the dominant wind direction. 4. The structural efficiency of the analyzed sections indicates that the column base and base plate were designed at their limits, while anchor rods were overdesigned. This was done due to uncertainties in the calculation of the tension force in anchor rods. 5. It was determined that the billboard behaves elastically for all evaluated wind speeds. However, high displacements were obtained, reaching 1250 mm for the reference wind speed of 220 km/h at 45\({}^{\circ}\) wind direction. Considering the dynamic effect caused by wind, large oscillations could happen, damaging elements attached to the panel or provoking structural elements to become loose. 6. Single post billboards cannot withstand more than 20 km/h of wind speed increment for any case of evaluated COV and \(\lambda\) values taken for the reference design wind speed of 180 km/h. 7. Wind codes could provide the fundamentals for performing CFD analysis in billboards prone to dynamic interaction with wind and to prove its accuracy. Furthermore, a methodology as presented here, should be provided to determine the safety level of billboards in places where there is uncertainty about the wind speeds and their probabilistic parameters. To sum up, reliability analysis of flexible single-post billboards indicates that these structures are prone to having safety levels below what is considered as the minimum level if the bias factor and coefficient of variation are higher than that defined for codes. Conceptualization of the structural model, J.Y.M.-M. and A.G.; conceptualization of the fluid model, E.A.E.-H. and I.E.H.-D.; methodology, including reliability analysis, R.S.-E.; software analysis, E.A.E.-H.; formal analysis, R.S.-E. and E.A.E.-H.; writing--original draft preparation, R.S.-E. and F.C. ; writing--review and editing, A.L.H.-M. and S.A.Z.C. ; funding acquisition, J.Y.M.-M. and A.G. All authors have read and agreed to the published version of the manuscript. Not applicable. Not available. The authors would like to acknowledge the support given to this study by [PERSON], [PERSON], [PERSON] and [PERSON] during the elaboration of their bachelor theses performed in Universidad Veracruzana. The authors acknowledge the financial support of Universidad de Guanajuato Campus Celaya-Salvatierra and Universidad de Guanajuato Campus Irapuato-Salamanca for the payment of the article processing charge (APC) for publication in open access. The authors declare no conflict of interest.