Experimental Research On Seismic Behavior Of Reinforced N-block Masonry Shear Wall Built With Straight-lint Joint

N-block masonry wall is a kind of masonry wall with the feature of fully aligned web-shells. It is recognized that cracking, water seepage and other engineering problems have been effectively mitigated by this kind of masonry wall, which has broad prospect of application. And this type masonry wall can be built with straight-lint joint. However, experimental study on its mechanical behavior is still limited. With the financial support from the construction technology research project of HuNan Province - Experimental Research on Seismic behaviors of Reinforced N-block Masonry Shear Wall, and based on previous research achievements on normal block masonry and N-block masonry wall, the basic mechanical performance of N-block masonry prism built with straight-lint joint, the seismic performance of reinforced N-block masonry reinforced shear wall built with straight-lint joint has been researched and analyzed.First of all, expatiated the N-type block masonry built with straight-lint joint construction methods, via the N-type block-shaped, and differences comparison between N-type block masonry structure with concrete block masonry.Through tests of 6 (6 half-grouted) block masonry specimens built with straight-lint joint on compressive behaviors, failure shape, cracking load, ultimate capacity and deformation capacity of were determined. Test results showed that, comparing with common concrete block masonry, due to special sectional geometric shape of N-block, the web-shell of N-block masonry exhibited favorable aligned ratio, the compressive behavior was better improved, and cracking load, compressive strength and elastic modulus of N-block masonry had been enhanced. Based on the compression mechanism of N-block masonry, a semi-empirical and theoretical formula of compressive strength is presented for grouted N-block masonry. And results calculated by the formulas were in good agreement with the test results. According to the test data of stress and strain, the stress-strain curve and modulus had been fitted, and the corresponding numerical expressions were also presented.Via the experiments of 3 (3 half-grouted) shear specimens built with straight-lint joint on shear performance, the shear failure characteristics were studied. According to the phenomenon of the shear tests, its shear failure mechanism was analyzed, based on previous research achievements and under the comprehensive consideration of the favorable restriction effect of external block on the core columns, relevant shear resistant formula of grouted N-block masonry was established, and results calculated by the formulas aligned well with the test results.Through experimental researches of two reinforced N-block masonry shear walls under the lateral cyclic load, the failure parttern, ultimate strength, hysteretic characteristics, and ductility and so on which all were indexes of seismic performance had been preliminarily investigated. Test results indicated that reinforced N-block masonry shear wall built with straight-lint joint had higher ultimate bearing capacity comparing to ordinary concrete block masonry shear walls, and when axial compressive stress is lower, ductial bending failure is more inclined to happen. The magnitude of vertical compressive stress and the quantity of horizontal steel and the quantity of vertical steel were three main factors which affected the ultimate strength and failure mode of the reinforced N-block masonry shear wall built with straight-lint joint. In the design of wall, the interrelation of the three factors should be simultaneously considered to satisfy the requirement of strong shear weak bending, in order to achieve bending failure with good ductility.