Wall Beam Structure Elastoplastic Analysis

The wall beam structure has been widely used in our city and country construction. It has many merits such as:saving steel, cement and timber;reducing labor and time and etc. Its bearing mechanism possess unique speciality. Based on the plastic theory and adopted the method of deformation theory, the paper studied wall beam speciality in bearing vertical load, rules of distribution of stress and influence factors. Through analyzing and summarizing the recent theoretical researches on constitutive models and failure criteria for brick masonry, a combination of a useful constitutive model with a reasonable failure criterion is used for describing the behavior of brick masonry under in-plane load. A finite element program of wall beam structure under elasto-plasticity condition is compiled and used to test some practical samples. The result is perfect.Through contrast analysis and graphs showing, there are many rules of distribution of stress and strain have been made. The result shows that:(1) In bearing vertical load the wall beam has arch domino effect. The vertical stress distribution presents the character that it's small in mid-span and it's big in the two sides on the boundary section of masonry and joist.(2) The character of mid-span joist accords with the plane section premise of bending member in the phrase of elasticity and plasticity under the vertical load. Normalized mid-span level stress and level strain in joist under plastic phrase is higher than that under elastic phrase in the same section.(3) The vertical stress distributing shape in plastic brick masonry is same as it in elastic brick masonry, presented the shape of basin. The vertical stress of each level section increases with the vertical load increasing. But the level section normalized vertical stress in masonry does not change in evidence with the vertical load. The basin shape of normalized vertical stresschanges gradually till flat from the bottom of brick masonry to the top of brick masonry. Normalized mid-span level compressive stress and level compressive strain in masonry change in evidence with the vertical load and which under plastic phrase is higher than that under elastic phrase in the same section.(4) The plastic phrase distributing proportion of supporting resistance on equal-span continuous wall beam is almost the same as the elastic phrase distributing proportion.(5) The stress of side-span steel element is bigger than other span in equal-span continuous wall beam under the vertical load.