In order to enhance the durability of steel encased concrete beams, a new type of steel reinforced engineered cementitious composite(SRECC) beam composed of steel shapes, steel bars and ECC is proposed. The theoretica...In order to enhance the durability of steel encased concrete beams, a new type of steel reinforced engineered cementitious composite(SRECC) beam composed of steel shapes, steel bars and ECC is proposed. The theoretical analyses of the SRECC beam including crack propagation and stress-strain distributions along the depth of the composite beam in different loading stages are conducted. A theoretical model and simplified design method are proposed to calculate the load carrying capacity. Based on the proposed theoretical model, the relationship between the moment and corresponding curvature is derived. The theoretical results are verified with the finite element analysis. Finally, an extensive parametric study is performed to study the effect of the matrix type, steel shape ratio, reinforced bar ratio, ECC compressive strength and ECC tensile ductility on the mechanical behavior of SRECC beams. The results show that substitution concrete with ECC can effectively improve the bearing capacity and ductility of composite beams. The steel shape and longitudinal reinforcement can enhance the loading carrying capacity, while the ductility decreases with the increase of steel shape ratio. ECC compressive strength has significant effects on both load carrying capacity and ductility, and changing the ultimate strain of ECC results in a very limited variation in the mechanical behavior of SRECC beams.展开更多
Ceramics can keep their mechanical characteristics up to 2 000℃ or higher.In this paper,A model to predict ultimate strength of continuous fiber-reinforced brittle matrix composites is developed.A statistical theor...Ceramics can keep their mechanical characteristics up to 2 000℃ or higher.In this paper,A model to predict ultimate strength of continuous fiber-reinforced brittle matrix composites is developed.A statistical theory for the strength of a uni-axially fiber-reinforced brittle matrix composite is presented.Also a semi-empirical frictional heating method for estimating in-situ interfacial shear in fiber-reinforced ceramic matrix composites was improved.Local uneven fiber packing variation as well as uneven micro-damage during fatigue can be expected to have effects on the composites:generation of frictional heating,thermal gradients,and residual stresses around local fiber breaks.This study examined those engineering interests by the finite element method.展开更多
We proposed a bilinearity constitutive curve model of fiber reinforced polymer(FRP) confined concrete which includes a parabola in the first stage and a straight line in the second stage. The FRP-confined concrete has...We proposed a bilinearity constitutive curve model of fiber reinforced polymer(FRP) confined concrete which includes a parabola in the first stage and a straight line in the second stage. The FRP-confined concrete has powerful confinement status and weak confinement status leading to different equations of parabola. We analyzed the impacts of factors such as confinement ratio and restrain stiffness on confined concrete compressive strength,ultimate strain and other control parameters through finite element analysis. The results show that the confinement ratio determines the confinement status,and the increase of the confinement ratio has a limited capacity to increase the compressive strength. The deformation of confined concrete is influenced by restrain stiffness. The stronger the restrain stiffness is,the less the lateral deformation is and the greater ultimate axial strain will be. The consideration of equivalent section coefficient kse is needed in the non-circular section confined concrete. We analyzed the results and proposed boundary values of strong and weak confinement styles,a peak/inflection point stress and strain model,and a compressive strength and ultimate strain model.展开更多
基金The National Natural Science Foundation of China(No.51778183)the National Key Research and Development Program of China(No.2016YFC0701907)the Distinguished Young Scholar Foundation of Jiangsu Province(No.BK20160027)
文摘In order to enhance the durability of steel encased concrete beams, a new type of steel reinforced engineered cementitious composite(SRECC) beam composed of steel shapes, steel bars and ECC is proposed. The theoretical analyses of the SRECC beam including crack propagation and stress-strain distributions along the depth of the composite beam in different loading stages are conducted. A theoretical model and simplified design method are proposed to calculate the load carrying capacity. Based on the proposed theoretical model, the relationship between the moment and corresponding curvature is derived. The theoretical results are verified with the finite element analysis. Finally, an extensive parametric study is performed to study the effect of the matrix type, steel shape ratio, reinforced bar ratio, ECC compressive strength and ECC tensile ductility on the mechanical behavior of SRECC beams. The results show that substitution concrete with ECC can effectively improve the bearing capacity and ductility of composite beams. The steel shape and longitudinal reinforcement can enhance the loading carrying capacity, while the ductility decreases with the increase of steel shape ratio. ECC compressive strength has significant effects on both load carrying capacity and ductility, and changing the ultimate strain of ECC results in a very limited variation in the mechanical behavior of SRECC beams.
文摘Ceramics can keep their mechanical characteristics up to 2 000℃ or higher.In this paper,A model to predict ultimate strength of continuous fiber-reinforced brittle matrix composites is developed.A statistical theory for the strength of a uni-axially fiber-reinforced brittle matrix composite is presented.Also a semi-empirical frictional heating method for estimating in-situ interfacial shear in fiber-reinforced ceramic matrix composites was improved.Local uneven fiber packing variation as well as uneven micro-damage during fatigue can be expected to have effects on the composites:generation of frictional heating,thermal gradients,and residual stresses around local fiber breaks.This study examined those engineering interests by the finite element method.
基金Funded by the Science and Technology Plan Project (No. 62065) of Guangzhou.
文摘We proposed a bilinearity constitutive curve model of fiber reinforced polymer(FRP) confined concrete which includes a parabola in the first stage and a straight line in the second stage. The FRP-confined concrete has powerful confinement status and weak confinement status leading to different equations of parabola. We analyzed the impacts of factors such as confinement ratio and restrain stiffness on confined concrete compressive strength,ultimate strain and other control parameters through finite element analysis. The results show that the confinement ratio determines the confinement status,and the increase of the confinement ratio has a limited capacity to increase the compressive strength. The deformation of confined concrete is influenced by restrain stiffness. The stronger the restrain stiffness is,the less the lateral deformation is and the greater ultimate axial strain will be. The consideration of equivalent section coefficient kse is needed in the non-circular section confined concrete. We analyzed the results and proposed boundary values of strong and weak confinement styles,a peak/inflection point stress and strain model,and a compressive strength and ultimate strain model.
