Damage Characteristics of Cracked TMT Reinforcement Bars

AbstractThermo-mechanically treated (TMT) bars have rapidly replaced the conventional High Yield Stress Deformed (HYSD) bars in RCC constructions. Due to the heat treatment on TMT bars, the surface toughness of such bars gets altered. Crack initiation and propagation characteristics of such bars vary significantly from that of conventional HYSD bars. Micro-cracks usually develop in bars at bend regions or may be appearing in straight region due to accidental overloads. Prominent cracks may develop due to the 90o bends at various locations, for example at beam ends. These cracks reduce the load carrying capacity and may lead to failure at stress levels much below the yield stress. Moreover, the surface cracks at bends are larger in bars with diameters over 16mm, amplifying their effect on the bars. Hence, it becomes imperative to study the failure characteristics of TMT bars and understand the progression of damage or cracks in the bars once the surface region has been already damaged

A generalized higher-order theory for multi-layered, shear-deformable composite plates

A generalized higher-order theory describing the mechanical behavior of multi-layered composite plates with arbitrary lamination scheme is proposed. Ritz’s method is employed to determine the kinematic unknowns expressed in a complete polynomial power series of the thickness-wise coordinate whereas the dependence on the in-plane coordinates is such that the functions satisfy all boundary conditions. The correct constitutive laws of a three-dimensional orthotropic elastic continuum are employed for each individual layer. The convergence and accuracy of the computational scheme are investigated by comparing elastic static and buckling results with analytical or finite element solutions for complex cross- and angle-ply laminates. For further validation of the theory, laminated plates under a transverse pressure are investigated for technically relevant lamination schemes and the associated deformation and stress results are compared with those obtained through FE calculations