Analysis On Inflation Deployment And Deflation Collapse Of Air-inflated Fabric Arches

Air inflated fabric arch structure is a type of spatial structure comprised of slender airtight membrane members and compressed air.It has obvious advantage of being light-weight,able to accommodate large spans,low cost,easy mobilization and reusable.Along with the development of experimental and theoretical analysis,it has been widely applied to civilian,military,and aerospace structures.However,its slenderness and flexibility introduce potential deployment difficulties during construction phase and may cause evacuation problems in the service stage when it is subjected to accidental ventilation.Related researches are very few.This study focuses on air-inflated arches.The development of related experimental and theoretical research is reviewed.The work includes experimental tests,numerical simulation analysis,and simple analytical method deduction in regard to their dynamic deployment and collapse performance:(1)Realtime pressure monitoring,continuous high-resolution video and camera recording,setting gridlines on wall for displacement measurement and etc.were applied to collect experimental data according to features of dynamic tests.Four single arches of different shapes and one large scale arch frame were designed and tested.Tension tests on membrane were conducted.The deployment and collapse behavior were investigated and summarized.The impact of geometric parameters,initial layouts,and external faciliations on dynamic behavior was studied.The results show that both deployment and collapse behavior shows strong regularity.Geometric parameters of arches and their initial deflated layouts have significant influence on the deployment pressure.External facilitations help to substantially lower the deployment pressure.The arches will collapse rapidly when they are subjected to accidental ventilation.The design parameters,constraints,and internal pressure have limited influence on anti-collapsing capacity of arches.It is recommended to take other measures to ensure emergency evacuation.(2)Dynamic simulation theory was reviewed.Control volume method based on thermodynamics was applied to simulate the inflation and deflation of arches.Modeling programs were developed to solve difficulties in creating control volume finite element models.Research was conducted on influence of finite element meshing,control volume divisions,and shapes of gas exchanging virtual diaphragms.Indirect measures were explored to achieve initial pre-stressed deployed models by inflation analysis,develop stress-free flat models by deflation analysis,and create all kinds of folded models by applying external forces and constraints in deflation analysis.The improvement on computation efficiency was studied by amplifying membrane parameters and applying “fast-slow” combined air flow rate.Refined meshing and less wrinkling models were proposed to solve contact issues.Dynamic analysis was conducted to simulate deployment and collapse behavior of arches and reveal membrane stress development.Results were summarized and compared with tests.In general,control volume algorithm is capable of simulating and predicting dynamic behavior of airinflated arches.Although simulated behavior and pressure-time/volume-time history differ from experimental observations,the key parameters of deployment pressure and collapse duration are in good agreement.The advantages of high calculation efficiency and being able to cover wide range of applications are prominent.(3)Based on thermodynamics,elastic mechanics,characteristics of air-inflated arches and its application environments,simple analytical methods were proposed to predict the deployment pressure of bent members,gas flow rate through venting openings,and anticollapsing performance of beams and arches.Case studies were conducted to evaluate the effectiveness and efficiency of the simple methods.Limitations were also discussed.The simple method for air-inflated structures was expanded to cover air-supported structures so as to enhance its practical applications.This work is helpful for understanding deployment and collapse dynamics of air-inflated arches.It can also help to solve deployment problems and provide guidance to their evacuation design.The test and analysis experiences can provide reference for improving dynamic test method,carrying out further simulation and developing other simple solutions so as to promote the application and development of air-inflated arches.