Research On The Performance And Application Of Spoiler On The Low-rise Building

China is a country with many typhoons.Every year,typhoon disasters bring about grave loss to the life and property of Chinese people and the national economy.Wind disaster statistics have showed that most of low-rise buildings in rural areas have been destroyed by typhoons,which is the main reason for casualties and economy losses.The mechanism of wind-induced damage of low-rise buildings has been revealed.The roof system is the first part of buildings to be damaged in strong wind.Then,the internal pressure of building has changed,which caused the damage of main structure of buildings.Thus,it is meaningful to increase the wind-resistant ability of roof system of low-rise building.The traditional method to increase the wind-resistant ability of roof system are broadly classified into two categories:increasing the weight of building envelop and enhancing the integrity of roof system.However,these two methods have many shortcomings such as high cost,limited effect,complicated construction and not being suitable for completed buildings.The aerodynamic mitigation devices caused the concerns of most researchers,because they can lower the uplift pressures in the corner and edge zones and save roofing material and requirements.The good effects of the aerodynamic mitigation devices on mitigating roof pressure has been widely accepted.However,these devices have not been generalized and applicated in practice.The main reason is that the mechanism of the mitigation device changing the wind pressure and the flow field has not been revealed,and the wind load on the mitigation device and the influence of mitigation device on wind-induced loss of buildings are unknown.Thus,there is no design method of mitigation device,and the influence of the mitigation device on economy loss can not be investigated.Based on this,this study was conducted to investigate the influence of spoiler,which is a typical aerodynamic mitigation device,on the wind pressure and flow field on building roof,and the design method of spoiler are proposed based on the test results.Besides,a wind-induced construction loss model for low-rise buildings with mitigation device is proposed.The main research contents are shown as follows:(1)The current study conducted wind tunnel tests to verify the mitigation effect of spoiler on roof pressure.And the influence of geometric factors including the spoiler width,angle and height on gable roof pressure has been investigated.The mechanism of the influence of spoiler on roof pressure and the influenced partitions of spoilers are revealed.Based on the test results,the design method of the arrangement and geometric factors of spoilers are provided.(2)The wind tunnel test model has been modified to measure the wind pressure on spoiler itself by two U-shaped steel panels containing pressure tubing.The distribution of net pressure on spoiler and wind pressure on upsides and downsides of spoiler are provided.The relation between the uplift force of spoiler and wind direction are revealed.Based on the test results,a more realistic roof uplift force is evaluated by considering the wind loads on the spoiler.(3)The fluid-structure interaction(FSI)numerical simulation was conducted with a flat roof building with a spoiler on eave to investigate the fluid-structure interaction effects between spoiler and flow field.The influence of spoiler deformation on roof pressure and uplift force on spoiler has been revealed.(4)Based on the fluid-structure interaction(FSI)numerical simulation results,the calculation method of spoiler deformation magnitude and spoiler performance has been provided,which has been verified by comparing the roof pressure and spoiler deformation magnitude of three gable roof buildings from FSI simulation with that from calculation method.Based on the calculation method,a simple design method for the spoiler stiffness was provided and applied in an actual gable roof building in southeast of China.(5)The CFD numerical simulation was conducted to investigate the interference effects among low-rise buildings with mitigation device.The wind pressure on building roof was used to calculate the wind load.Based on the existing wind-debris model and envelope structure damage mode,the wind-induced envelope structure loss model for low-rise buildings with mitigation device is proposed.The influence of spoiler on the envelope structure loss of building group has been investigated by the proposed loss model.The design suggestions about mitigation devices using in building group has been proposed.Based on the results of loss assessment of building group,the economy loss of an actual village with 50%and 80%installation ratio of spoiler has been predicted,which verified that installation mitigation device is meaningful to reduce economy loss of building group in rural areas.