Mechanical as well as durability properties are pivotal for any type of concrete which gets adversely affected due to cracks that may form due to loading beyond its capacity.Concrete has the intrinsic property to heal...Mechanical as well as durability properties are pivotal for any type of concrete which gets adversely affected due to cracks that may form due to loading beyond its capacity.Concrete has the intrinsic property to heal itself to some extent but not fully as the passive form of autogenous healing plays an inferior role for a complete repair of a cementitious material.The self-healing capabilities can be enhanced by adding chemical admixtures,polymers,and bacteria strains induced calcium carbonate precipitation,etc.In this paper,the advancements in the development and performance of self-healing concrete using chemical admixtures,polymers,and bacteria strains are reviewed.This systematic review includes the available experimental tests and methodologies investigating self-healing efficiency over the last decade.Further,this review focussed on self-healing materials,the ideology,and opinions of those in the construction field on the direction of self-healing concrete for future applications.It is yet not possible to predict the most appropriate technique,however,a generalized opinion about the effectiveness of the different approaches has been illustrated.展开更多
A variety of new materials in the field of concrete technology have been developed during the past three decades with the ongoing demand of construction industry to meet the functional, strength, economical and durabi...A variety of new materials in the field of concrete technology have been developed during the past three decades with the ongoing demand of construction industry to meet the functional, strength, economical and durability requirements. Though reinforced concrete has high strength and is most widely used construction material it suffers from disadvantages like corrosion of steel, susceptibility to chemical and environmental attack. In order to overcome the above deficiencies of reinforced concrete new materials （special concrete composites） have been developed over the past three decades. Glass Fibre Reinforced Polymer （GFRP） is one such material with wide range of applications. Based on the preliminary investigations on GFRP bars, an optimum fiber/resin ratio of 7：3 was arrived. The tensile strength of GFRP bars is comparable to that of the mild steel as per the tests carried out, but the modulus of elasticity is about 25-30 percentage of that of steel bars. This paper deals with the experimental investigations carried out on small slab panels supported on all four edges with effective spans of 0.9 m ~ 0.45 m, which is a part of large research problem undertaken with different ratios of 10ng span to short span with different support conditions. The test results are compared with similar slab panels reinforced with conventional mild steel bars.展开更多
A new spherical triangular finite element based on shallow shell formulation is developed in this paper. The element has six degrees of freedom at each comer node, five of which are the essential external degrees of f...A new spherical triangular finite element based on shallow shell formulation is developed in this paper. The element has six degrees of freedom at each comer node, five of which are the essential external degrees of freedom and the additional sixth is associated with the in-plane shell rotation. The displacement fields of the element satisfy the exact requirement of rigid body modes of motion. The element is based on independent strain assumption insofar as it is allowed by the compatibility equations. The element developed herein is first validated by applying it to the analysis of a benchmark problem involving a standard spherical shell with simply supported edges. The results of the analysis showed that reasonably accurate results were obtained even when modeling the shells using fewer elements compared to other shell element types. The element is then used in a finite element model to analyze polygon shaped spherical roof structures. The distribution of the various components of deflection and stress is obtained. Furthermore, the effect of introducing circular arched beams as stiffeners spanning the two diagonally opposite end comers is investigated. It is found that the stiffeners reduced the deflections and the stresses in the roof structure by considerable value.展开更多
文摘Mechanical as well as durability properties are pivotal for any type of concrete which gets adversely affected due to cracks that may form due to loading beyond its capacity.Concrete has the intrinsic property to heal itself to some extent but not fully as the passive form of autogenous healing plays an inferior role for a complete repair of a cementitious material.The self-healing capabilities can be enhanced by adding chemical admixtures,polymers,and bacteria strains induced calcium carbonate precipitation,etc.In this paper,the advancements in the development and performance of self-healing concrete using chemical admixtures,polymers,and bacteria strains are reviewed.This systematic review includes the available experimental tests and methodologies investigating self-healing efficiency over the last decade.Further,this review focussed on self-healing materials,the ideology,and opinions of those in the construction field on the direction of self-healing concrete for future applications.It is yet not possible to predict the most appropriate technique,however,a generalized opinion about the effectiveness of the different approaches has been illustrated.
文摘A variety of new materials in the field of concrete technology have been developed during the past three decades with the ongoing demand of construction industry to meet the functional, strength, economical and durability requirements. Though reinforced concrete has high strength and is most widely used construction material it suffers from disadvantages like corrosion of steel, susceptibility to chemical and environmental attack. In order to overcome the above deficiencies of reinforced concrete new materials （special concrete composites） have been developed over the past three decades. Glass Fibre Reinforced Polymer （GFRP） is one such material with wide range of applications. Based on the preliminary investigations on GFRP bars, an optimum fiber/resin ratio of 7：3 was arrived. The tensile strength of GFRP bars is comparable to that of the mild steel as per the tests carried out, but the modulus of elasticity is about 25-30 percentage of that of steel bars. This paper deals with the experimental investigations carried out on small slab panels supported on all four edges with effective spans of 0.9 m ~ 0.45 m, which is a part of large research problem undertaken with different ratios of 10ng span to short span with different support conditions. The test results are compared with similar slab panels reinforced with conventional mild steel bars.
文摘A new spherical triangular finite element based on shallow shell formulation is developed in this paper. The element has six degrees of freedom at each comer node, five of which are the essential external degrees of freedom and the additional sixth is associated with the in-plane shell rotation. The displacement fields of the element satisfy the exact requirement of rigid body modes of motion. The element is based on independent strain assumption insofar as it is allowed by the compatibility equations. The element developed herein is first validated by applying it to the analysis of a benchmark problem involving a standard spherical shell with simply supported edges. The results of the analysis showed that reasonably accurate results were obtained even when modeling the shells using fewer elements compared to other shell element types. The element is then used in a finite element model to analyze polygon shaped spherical roof structures. The distribution of the various components of deflection and stress is obtained. Furthermore, the effect of introducing circular arched beams as stiffeners spanning the two diagonally opposite end comers is investigated. It is found that the stiffeners reduced the deflections and the stresses in the roof structure by considerable value.
