Study On Mechanical Properties Deterioration Laws Of Perforated Brick Masonry After Fire Exposure

The development of masonry architecture in our country has a long history.With the development of production technology,besides the original sintered clay solid brick,clay perforated bricks,Fly-ash perforated bricks,concrete perforated brick etc are also appeareded successively.All of these greatly enrich and develop the masonry structure,which makes the masonry structure still has a place in the future.After a series of national policy propaganda and popularization,people’s consciousness on the environment and resources protection constantly deepened.Coupled with the advantages of itself energy-saving,land-saving,as well as good mechanical properties,so in the past ten years perforated brick masonry structure has been a large number of applications in our building construction,and perforated brick will completely replace clay solid brick as building structure wall materials.According to statistics,the occurrence of building fire disaster presents a tendency of increasing,the fire is of great destructive effects and results in vast of property losses and casualties.Masonry structure often has the problems about higher population and housing density,poor fire protection measures etc.These factors not only increased the frequency of the masonry building fire disaster,also makes the damage of masonry building after the fire is more serious.However,the researches concerned with the fire resistance of masonry structure are only in the beginning stage in China.Although there are numerous scholars devote themselves to the experimental and theoretical study of masonry structure,the achievements could not meet the requirements of application.What’s more,the researche on the mechanical properties of perforated brick masonry after fire exposure has not been carried out.Considering the situation stated above,enhancing the research of mechanical properties of perforated brick masonry after fire exposure is of great significance.In this paper,perforated brick masonry specimens was studied.At first,experiment of mechanical properties of clay brick masonry after standard fire was conducted.Then a simulation of the mechanical behavior of masonry structure was carried out.The contents of this paper can be divided into several parts above.(1)The achievements refer to properties of masonry structures exposed to high temperature obtained by domestic and alien scholars was concluded.(2)Compressive experiments on perforated brick masonry standard specimens was carried out.There were two groups of specimens in room temperature,and six group of specimens after fire exposure.The effect of mortar strength,duration under fire and cooling regime on the properties of perforated brick masonry structure under pressure was observed.Eventually,the variation of compressive strength,elastic modulus and stress-strain relationship of perforated brick masonry specimens versus duration under fire were obtained.(3)Shear experiments on perforated brick masonry standard specimens was carried out.There were two groups of specimens in room temperature,and six group of specimens after fire exposure.The effect of mortar strength,duration under fire and cooling regime on the shearing properties of perforated brick masonry structure was observed.Eventually,the variation of shear strength of perforated brick masonry specimens versus duration under fire were obtained.(4)According to the existing research results,this paper proposed a kind of numerical calculation method for calculating the compressive strength of perforated brick masonry.Based on ABAQUS,the process of masonry compressive specimens in fire was simulated,and temperature field distribution was obtained.Then through mathematical calculation method,the relationship between compressive strength of masonry material under and after high temperature exposure was analyzed.Finally on the basis of the research above,layer method is used to calculate the compressive strength of perforated brick masonry structure after fire,and results had good agreement with experimental values.(5)A foreign existing compressive experiment on masonry structure after high temperature exposure was checked by this numerical calculation process.By comparing the experimental results with the calculated results,the validity of the numerical method in solving other fire conditions(different specimen sizes,different heating curves,and different fire surfaces)is further verified.