Experimental Study On Strengthen Technology For Stone Slabs

Stone slabs are widely used as floor members in stone masonry buildings in thesoutheast of China. These buildings are under potential risk against earthquakes. In order toenhance the integrity and bearing capacity of the stone slabs, a new strengtheningtechnique with inner ring-beam and ferrocement was proposed in this dissertation. Thefollowing studies were conducted.A total of thirty pull-out tests were conducted to investigate the bond behaviorbetween the stone and the embedded steel rebars. The main test parameters included thebonded length, the adhesive type, and the surface characteristic of the rebars.Recommendations on the configuration of embedding steel rebars into the stone were putforward based on the test results.With the purpose of improving the seismic weakness of poor integrity and insufficientsupported length in stone slabs, the technique of adding inner ring-beam beneath the stoneslabs was proposed. Six specimens were tested to study the interfacial behavior betweenthe ring-beam and the stone block. The test parameters included the amount of U-shapedstirrup, surface characteristic of the rebar and the loading position. Test results showed that:(1) The bearing capacity of specimen increased along with the usage of U-shaped stirrup;(2) The bearing capacity of specimen with ribbed rebars was higher than that with roundrebars;(3) The bearing capacity increased with the decrease of the force arm. Based on thetest results and mechanical analysis, a model to calculate the load-carrying capacity wasproposed.Bending testes were carried out on seven stone multi-slabs and three single-slabs tostudy the influence of strengthening method, mortar strength, and reinforcement ratio onthe flexural behavior of the strengthened slabs. Test results showed that:(1) The crackingmoment and ultimate moment were not increased for the slabs strengthened in the joints,while the deformation capacity was significantly improved;(2) Both of the strengtheningmethods could effectively increase the bearing capacity, deformation capacity and ductility;(3) The two strengthening methods had the same effect and could be used in engineering application;(4) Increasing the reinforcement ratio could increase the cracking moment andultimate moment of the strengthened slabs;(5) The mortar strength had little influence onthe cracking moment and ultimate moment of the strengthened slabs;(6) Plane sectionremains plane when the strengthened slab deformed.Based on experimental results and the plane-section assumption, the flexural capacityof the strengthened stone slabs was mechanically analyzed, and the model to calculate theminimum reinforcement ratio was proposed. The equations, which were proposed by ourresearch group, were checked by the test datas. The predicted results agreed well with theexperimental once, and the model could be referenced for the engineering application.