Experimental Study On Failure Form And Deformation Behavior Of Mansard Steel Beam

Reinforced concrete structure is the most widely used and the most common of building structure. But from raw material production to the building demolition, reinforced concrete structure produces a lot of garbage, which seriously contaminates the environment. However, steel structure building has many advantages, such as light weight, high strength, good mechanical properties, excellent seismic performance, high degree of industrialization, rapid construction speed, aesthetic appearance, fast invest retrieve and so on, which conform to industrialization and sustainable development. In recent years, steel structure building in our country becomes more and more popular. The structure system of mansard steel beam is a kind of the special form of composite RCS moment frames system. It can exert the advantages of the two materials at the same time. First, it can give full play to the specialty of steel and concrete, and maintain suitable for large-span building traditional advantage. Second, the stiffness and stability problems of reinforced concrete columns are easy to solve. With good compression performance, excellent durability and fire resistance of reinforced concrete, structural costs and maintenance costs are greatly reduced. When using reinforced concrete column, people can match it with lightweight masonry wall to solve the problem of the durability of building insulation and wall. Upper with light weight high strength steel beam and light roofing accelerate the construction speed and reduce the construction cost. Moreover, reinforced concrete raw material cost is low, and the theory and construction technology is mature, which reduces the cost of fire prevention. It also has practical significance in anti-corrosion.Mansard steel beam in the structural system must be highly safe and reliable, which is the premise to guarantee the normal work of the structure and it is the core of this structure system. Further study of mansard force performance of steel structure system is the precondition of reasonable design of reinforced concrete. Scholars at home and abroad have some researches about concrete column-hybrid girder components, but there is fewer research about mansard steel beam structure system. This paper proposes five different slope of experimental research to inspect failure form and deformation behavior of mansard steel beam in the structural system in under concentrated load. The main contents of this paper about the results of research and analysis the following aspects are as follows:1. Observe the mansard steel beams under concentrated load test in the process of damage phenomenon; analyze mansard steel beams in the process of stress deformation characteristics and failure mechanism; draw the mansard steel beam load curve and load-displacement curve of load-strain relationship and analyze the slope of the different linear beams through the analysis on the stress of the mansard steel beam under concentrated load until failure process. The results showed that the failure mode of mansard steel beam is unstable failure, the upper flange at the mid-span cause structural buckling distortion, both flanges have some protuberances, the splints at the support have a certain angle, the section at the mid-span is distortion of out-of-plane, which have large apical transportation with slope.2. From a theoretical point of view of mansard steel beam calculation analysis and derivation of the horizontal thrust calculation formula and other internal force calculation formula, and use the Matlab program for the horizontal thrust factors of mansard steel beam in the structural system, it is concluded that the horizontal thrust with variation of the influencing factors of the slope, the span and so on. Analysis results show that the horizontal thrust increase first and then decrease with the increase of the slope and increases with the increase of the span, when the position of the load is close to the mid-span, horizontal thrust is larger, when horizontal displacement is larger, horizontal thrust is smaller.3. Make use of ANSYS Workbench 14.0 finite element software to simulate the load of the mansard steel beam process, with the design of experiments in the process of simulation, the author consider the material constitutive relation, failure criteria, the initial defects such as simulation and compare them with the test results. Analysis results show that the slope of mansard steel beam is smaller, the total stress is bigger, which the having horizontal displacement is larger than the not having horizontal displacement under the same slope. The section strain increase with the increase of the load, which the having horizontal displacement is larger than the not having horizontal displacement and the loading point of section that is dangerous section is larger than the mid-span of section. The having horizontal displacement of neutral axis location is higher than the not having horizontal displacement under the same slope, which the mid-span section is higher than the loading point of section.