Study On Blast Resistance Of Reinforced Masonry Infill Wall Based On Impact Of Drop Hammer Machine

After9.11attack, the performance of structures under blast load has become oneof the topics in structural engineering field. Masonry infill wall which often works asexterior envelope component has been widely used in constructions. however, becauseof its poor out-of-plane load-carrying capacity and brittleness of masonry block, onceexposed to blast load, the wall is easy to be destroyed and produces fragments of highvelocity, which often result in casualties of indoor occupants. In order to improve thesafety reliability of masonry infill wall under blast load, it’s important to strengthenthe wall with reinforced materials in protective design. Considering the advantages anddisadvantages of existing testing method for masonry wall under blast load and therequirement of study, multi-stage impact tests of eight wall specimens were carried outusing the drop hammer machine of Center for Integrated Protection Research ofEngineering Structures. Also, a series of finite element simulations were conducted tomeasure the resistance of masonry infill walls under blast load. The main researchwork and achievements in this thesis are as follows:1. Impact test of two unreinforced wall specimens was conducted using drophammer machine. The load-carrying capacity of unreinforced masonry infill wallsunder impact was assessed and the feasibility of using drop hammer machine toinvestigate the behavior of blast-retrofit masonry walls was verified. The resultsprovide some references to related test researches.2. Drop hammer impact tests of masonry infill walls reinforced with CFRP andpolyurea protective panels were performed. The results show that increasing the layersof CFRP is benefit to inhibit the development of cracks on the wall, and continuouswoven sheets are better than continuous unidirectional. Although severe tearphenomenon have been captured on polyurea protective panels, the panels can stillbound fragments of masonry wall to exterior frame. Overall the protective performanceof polyurea protective panels is superior to CFRP. Also the drop hammer impact testmethod is discussed.3. The numerical analysis of unreinforced, CFRP and polyurea protective panelsretrofited masonry infill walls was conducted. The results show that failure mode ofunreinforced masonry wall depends to the value of peak overpressure; stiffness ofmasonry wall will greatly increase when reinforced with CFRP, but brittle fracture often happens when subjected to large lateral pressure because of the weakness ofstretch properties; reinforcing the wall with polyurea protective panels is helpless toimprove the load-carrying capacity, but it can still play a protective role under largepressure which is resulted from the good performance in stretch properties.