Research On Local Compressive Performance And Application To Shearing Connectors Of Lightweight Aggregate Concrete

In recent years,the maturity of lightweight aggregate concrete material has made it have great development in constructional engineering.Lightweight aggregate concrete is light,strong,fireproofing and durability,these characteristics are of great advantage in high-rise and large-span bridge's construction.So lightweight aggregate concrete has become an important direction of concrete.We must do a comprehensive and systemic study towards the force behavior of Lightweight aggregate concrete to promote the use of Lightweight aggregate concrete in construction,so that we can provide necessary operation basis to the engineers and technicians.Local compression is a common engineering structure in the form of force,for example,post-tensioned priestesses concrete structure anchored end zone,directly under the bearing plate of the local concentrated loads from the bridge pier hat,The hinged steel arch or support points all have local compression problem.Learn from foreign experience in preparation of lightweight aggregate concrete,and referring the relevant research results,in this paper,the author uses lightweight aggregate to produce the lightweight aggregate concrete mixing water reducing,and do research about the local compression.The full text is divided into six chapters,Chapter III,Chapters IV and V is the focal points of this article.Chapter I introduces the background,meaning and content of this research.With the development of construction technology,construction develops to large-span,high-level,so as to decrease the structure section,reduce the structure weight,the concrete must be of great strong and light weight.Because the lightweight aggregate and lightweight aggregate concrete get over the shortcoming of the concrete's heaviness,the production of lightweight aggregate and the use of lightweight aggregate concrete have become a important subject all of the world.Local compression is a common force form in engineering structure,the scholar at home and aboard do many experiment and study on common concrete local compression problem.But there are rare scholars doing research on lightweight aggregate concrete's local compression problem. Chapter II introduce the lightweight aggregate and lightweight aggregate concrete's definition and classification. Lightweight aggregate concrete can be divided into three main categories by the use:thermal insulation of lightweight aggregate concrete,structural insulating lightweight aggregate concrete,structural lightweight aggregate concrete.This paper mainly studies the local compression of the structure of lightweight aggregate concrete.Structural lightweight aggregate concrete has the advantages of light weight,high strength,fire resistance,and good seismic performance,impermeability,and durability,and comprehensive technical and economic effect.Chapter III,the focus of this paper, mainly studies the lightweight aggregate concrete theory. Local compression is the most common engineering structures form other researchers at home and aboard also carried out a series of experiment studies,at the same time,they worked out some mechanical models of the working principle of concrete partial pressure,which include the more classical theory such as hoop theory,the theoretical splitting wedge.This chapter studie the working principle of concrete local compression,and explain the local compression process of cracking and damage of Lightweight Aggregate Concrete with arching theory in according to wedge theory,it works out the mechanical model of local compression problem of lightweight aggregate concrete,and derives more satisfaction theoretical formula with limit equilibrium method.Through analysis of test data,we obtain the practical calculating formula in harmony with the normative formula.Chapter IV is the core of this article.On the basis of the experiments,this chapter studies the effects of different board positions,different forms of pressure and pore Board to the local compression strength of lightweight aggregate concrete.Through experimental analysis,we can see that the local compression strength and damage are the same as ordinary concrete,it can be divided into first-cracking-post-damage,cracking with damage and particle sink.In same condition of area and pressure,the lightweight aggregate concrete circularβpressure value is slightly larger than rectangular board pressure,and theβvalues of square partial pressure is between the two;theβvalues of trial target with holes has a direct relationship with the size of the holes,Bigger the holes,lower the local compression strength;bigger the ei,lower the local compression strength of roundness load;we can use reasonable Ab value calculating method to measure the effect of ei to paricle pressure strength.This chapter gives the design procedure of Ab,the calculation results from the method is in line with the measured value.Chapter V studies the strength of shear joints,and put the theoretical formula for local compression in use designing steel shear connectors.Through experimental analysis,we can consider the steel shear connector's pressure stress as local compression,and we can use the formula of local compression theory in the paper into the steel shear connectors'design.As for the normal size of the bolt shear connectors nail,the concrete stress state is complex under screw bolt,so it can not be calculated by the local compression theory.Chapter VI is the final chapter of this article.Be a summary of the full text,it summarizes the work and proposes the next step of the research.Innovation of this article:(1)propose the change rules of the local compression strength of lightweight aggregate concrete.(2)study the effects of different forms,holes to the strength of local compression and the calculating method of Ab value.(3)study the differences of local compression between lightweight aggregate concrete and ordinary concrete.(4)propose the calculating method of Ab value of the circular component's local compression,especially small component.(5)study the use of local compression in designing the shearing connector.