Mechanical Performance And Design Method Of Load-bearing Horizontal-hole Interlocking Concrete Block Masonry And Walls

Masonry structure is widely used in rural areas.With the development of the concept of building green and energy saving in China and the implementation of the policy of "no-stick",concrete block with relatively low energy consumption is increasingly used in low-rise masonry structure in villages and towns.At the same time,the types and forms of concrete block is constantly developing and changing.The research group proposed a kind of Load-bearing Horizontal-hole Interlock Concrete Block(LBHHIB),which has the advantages of convenient and fast masonry,low technical threshold,saving masonry mortar and coating mortar,etc.At present,the research group has systematically studied the block design,thermal performance and basic physical and mechanical properties of LBHHIB.On this basis,the research on the mechanical properties of LBHHIB and its masonry and wall,and the establishment of the calculation model and design method for LBHHIB masonry and wall are the premise of the promotion and application of LBHHIB.Based on the compression and shear resistance research of LBHHIB masonry and the seismic research of LBHHIB wall,this paper takes the LBHHIB,LBHHIB masonry and LBHHIB wall as the research object,and launches the full research,the main content is divided into the following parts.First of all,A total of 54 compressive specimens in nine groups were designed to study the compressive properties of the LBHHIB masonry.The specimens were made of BC240,BH240 and BH290 block blocks and masonry mortar of high,medium and low strength.The thickness of the specimens were 240 mm,240mm and 290 mm respectively,the height were all 1030 mm,and the ratio of height to thickness was 4.3,4.3 and 3.6,respectively.The specimen was subjected to axial compression test,the failure characteristics of the specimens were analyzed,the key factors affecting the compressive performance of masonry were clarified,and the compressive strength of masonry was obtained.Research has shown that the transverse tensile stress caused by masonry compression and the additional transverse tensile stress caused by mortar deformation lead to the tensile state at the transverse ribs of masonry,which is the main reason for the failure of masonry.The mortar strength and block strength have great influence on the compressive strength of masonry,the vertical rib ratio and block structure also affect the compressive strength of masonry by changing the stress condition of masonry;The compressive strength of the LBHHIB masonry is lower than that of the traditional vertical hole block masonry;The formulas for calculating compressive strength of LBHHIB masonry presented in this paper is suitable for predicting the compressive strength of the block masonry,which can guide the engineering design.Secondly,for the study of the shear performance of LBHHIB,the shear tests of three different block types of LBHHIB masonry are carried out,and a method to calculate the shear strength of LBHHIB masonry considering the effective bonding area is proposed,which makes up for the deficiency that the current code formula can only be used to calculate the shear strength of commonly used vertical hole concrete block masonry.However,the above formula has the problem of confusion between the calculated area and the measured area.On this basis,this paper modifies the shear strength calculation formula,compares it with the shear strength calculation formula of other types of block masonry,and puts forward the modified shear strength calculation formula of LBHHIB masonry.Finally,in order to study the seismic performance of LBHHIB wall,nine pieces of LBHHIB wall were designed and manufactured in this paper.These include a reference wall with side reinforced concrete columns,a wall without side reinforced concrete columns,a wall with horizontal reinforcement,a wall with increased strength of masonry mortar,a wall with increased vertical precompression stress,and a wall with altered block type.The above nine walls were tested under in-plane lateral cyclic load.The test results show that all the walls have oblique cracks along the diagonal line,and the failure mode is shear failure.On the analysis comparison of the wall of the hysteresis curves,skeleton curves,deformation and energy dissipation,stiffness degradation,this article found that the ductility and energy dissipation capacity of the wall without side reinforced concrete columns were poor,and the horizontal reinforcement embedded in the body of the wall,as well as the increased vertical compressive stress and mortar strength,improved the shear capacity of the walls,inhibited the development of cracks and delayed the rate of stiffness degradation,improving their overall seismic performance.Finally,a formula for predicting the seismic shear bearing capacity of LBHHIB walls is proposed,and the calculated values are in good agreement with the experimental values.To sum up,this project has established the calculation theory of LBHHIB masonry compressive resistance,shear resistance and seismic bearing capacity of the walls,put forward the calculation formula that can be used for design,solved the key technical problems of LBHHIB masonry load-bearing wall design,and can be used for the subsequent preparation of technical regulations.The results show that LBHHIB meets the compressive,shear and seismic requirements of load-bearing walls in China’s current code,and can be used in load-bearing walls of low-rise masonry structures.The combination of the LBHHIB wall and the prefabricated ribbed floor concrete laminated slab constructs a new type of assembled monolithic masonry structure system,which is suitable for the promotion and application of the village and town houses in the beautiful rural construction.