Study On Wind Pressure Zoning And Area Reduction Effect Of Saddle-shaped Roof

Roof is an important part of building,and the safety and economy of its wind-resistant design are important factors that affect the construction and use of buildings.At present,wind-induced disasters that cause partial or overall destruction of building roofs frequently occur.In order to reduce the occurrence of wind-induced damage to the roof,it is particularly important to use reasonable wind-resistant design methods to conduct wind-resistant research on the roof.At the same time,the saddle-shaped roof is used more in engineering,however,the standard related to the wind-resistant design of the saddle-shaped roofs has not been supplemented simultaneously.Therefore,the need for wind-resistant design research on saddle-shaped roofs is particularly urgent.The research of structural wind resistance design should consider both the safety of the design and the economic benefits as much as possible to achieve the optimal design plan.For building roofs,the extreme wind pressure in the windward front region is larger than the internal region.Based on the extreme wind pressure,the roof is divided into various zones,and the wind pressure of area reduction effect is studied for each zone.And then,the area wind pressure extreme value of each zone is determined as the design wind pressure to provide a reasonable reference for the wind resistance design of large-span roofs.Based on the above thoughts,this thesis takes the wind tunnel test data of the saddle-shaped roofs to study the wind pressure zoning and area wind pressure reduction effects.The main content includes the following aspects:1.Based on the wind tunnel test data,the wind pressure distribution law and wind pressure characteristics of the saddle roof are studied in various wind directions.Studies have shown that the wind pressure on the roof surface is unevenly distributed.The wind pressure decreases gradually along the downwind direction,in each wind direction.And the value of wind pressure on the entire roof is different.Secondly,the roof wind pressure is correlated,but the extreme wind pressures at different locations do not appear at the same time.2.According to the characteristics of uneven distribution of wind pressure on the roof surface,the saddle-shaped roof is divided into various wind pressure zones.In order to reduce the subjectivity of roof wind pressure zoning and to link roof wind pressure information with location information,a mixed zoning method and a three-dimensional clustering method that are superior to the existing zoning methods are proposed.Research shows that the wind pressure zoning method proposed in this thesis has wider applicability and effectiveness.3.Considering the correlation of roof wind pressure,the area average method and the moving average method are used to estimate the area wind pressure extreme for each zoning.And the logarithmic linear function is used to fitting curve of the area wind pressure extreme.The research results show that the area wind pressure extreme in different zones of the roof are quite different,and the area wind pressure extremes in each zone show a phenomenon of decreasing with the increase of the area.The wind pressure area reduction curve fitted in each zone can be used as the reference for selecting the design wind pressure value of the saddle roof,which is more convenient for designers to use.4.The theoretical formula of non-Gaussian stochastic process combination is used to calculate the extreme value of wind pressure,and the influence of wind pressure correlation and wind pressure gradient on the extreme value of combined is analyzed.The research results show that the results of the area extreme values of the wind pressure calculated by the area average method and the non-Gaussian random process combination method are consistent.At the same gradient value,the positive correlation coefficient is more sensitive to the influence of the combined extreme value than the negative correlation,and the larger the correlation coefficient,the larger the combined extreme value.In addition,the smaller the wind pressure extreme value gradient,the smaller the impact on the combined extreme value.When the extreme value gradient is less than 20%,the wind pressure extreme value gradient has little effect on the combined extreme value.