Experimental Study On Strengthening Technology For Historical Masonry Structures

The reinforcement of historic buildings pays more attention to the protection oftheir historical value and features. In order to meet the needs of protection of historicmasonry structures, three applicable methods for strengthening the masonry wall bymounting polymer mortar, steel plate and embedded constructional column areproposed. The effect and shear bearing capacity of the strengthened masonry wall arestudied. The main findings are summarized as follows:Eight retrofitted walls were tested under low cyclic loading to investigate theseismic performance of strengthened walls. Test results showed that:(1) The mainfailure mode of strengthened walls is shear-compression failure, part of wallsstrengthened by mounting steel plate in bed joints failed by sliding along horizontalmortar joint;(2) The improvement of seismic performance by mounting polymermortar in bed joints is not obvious, and the increase of bearing capacity anddeformation capacity is limited;(3) Mounting steel plate can improve the capacity ofenergy dissipation and deformation effectively;(4) Mounting steel plate can changebrittle nature of the brick wall, and its latter bearing capacity decreased slowly;(5)Mounting steel plate working with mounting polymer mortar can improve the bearingcapacity more obviously, however, in the latter loading, its hysteretic curve andskeleton curve were no changed;(6) The weak frame formed by embedding ringbeam and constructional column can provide effective constraint to the wall, as aresult, it is very effective in increasing the ultimate bearing strength and thedeformation capacity of strengthened walls;(7) The hysteretic loops of all wallsstrengthened by mounting in bed joints are of plump shuttle shape, while those byembedding ring beam and constructional column are in bow shape.Mounting steel plate in bed joint increased the tensile strength of wall, so theshear bearing capacity of the strengthened wall is controlled by the principal tensilestrength and the frictional resistance of mortar joint. Based on the existing model forcalculating the shear bearing capacity of masonry wall, a formula to calculate theultimate lateral shear capacity of the strengthened masonry wall is proposed.