A Nonlinear finite element based ABAQUS modeling studies were conducted to evaluate the performance of exterior Beam Column Joint (BCJ) under quasi-static test loads. Six integrated BCJ models representing different configurations of beam reinforcement anchored in joint are verified by using a novel retrofitting technique called "Post Installation of Supplementary Anchorage" (PISA) by using headed bar as supplementary steel. The configuration of beam reinforcement anchored in column are described by straight bar,90 degree bend ,180 degree hook (confirming to design code IS456:2000) and single head, double head bars (confirming to ACI 318-19, ACI 352R-02 ) and 90 degree long bend of ductile detailing (as per IS 13920-2016). Two series (A&B) of integrated joint specimens representing conventional (series-A) and retrofitted anchorage (series-B) systems are modeled and tested by using ABAQUS software. The test parameters considered are configuration of anchorage system and presence of supplementary anchorage. The test variables representing nonlinear performance of retrofitted joint system are Von Mises stress conditions, Principal tensile stress, Moment-Rotation, Degraded stiffness, Crack mechanics and Damage index. The results shows good improvement of post failure conditions of exterior beam-column joint such as relocation of plastic hinge mechanism and failure mechanics of retrofitted joint system. Also the results validated with experimental program on typical specimens casted and tested. This study imparts useful information on implicit retrofitting methods applied by external means in exterior beam-column joint. It also promotes performance based design principles with viable construction practice.

This work is aimed at formulating a polynomial function for the nonlinear analysis of CCCS isotropic rectangular thin plate. The previous researchers used trigonometry function as their shape function on the decoupled Von Karman’s equations to obtain particular stress and displacement function respectively. Trigonometry function can only be used effectively for SSSS and CCCC plates; apart from these boundaries conditions its efficiency reduces. This present work hence used a polynomial function to formulate the approximate shape function for the CCCS plate. Direct variational calculus was used applied on Von Karman’s equations to obtain the general form of minimized total potential energy which serves as a platform for the determination of coefficient factor( Amplitude or coefficient of deflection). The numerical values of CCCS plate under unit load were obtained using Amplitude equation formulated. These values were obtained for various aspect ratio (ranging from 1 to 1.5 with an increment of 0.1). This work was compared with the previous work [1] and the percentage difference in the results are within the acceptable limit. This results indicate that the approach adopted by the present work is adequate, reliable and satisfactory for the analysis of CCCS rectangular plate.

The work is aim at the development of a computer program for the nonlinear analysis of rectangular thin isotropic plate on Ritz method. Twelve boundary conditions were analyzed which include: SSSS, CCCC, CSCS, CSSS, CCSS, CCCS, CCFC, SSFS, CCFS, SCFC, CSFS, and SCFS. General expressions for displacement and stress functions for large deflection of isotropic thin rectangular plate under uniformly distributed transverse loading were obtained by direct integration of Von karman’s non-linear governing differential compatibility and equilibrium equations. Polynomial function as shape function was on the decoupled Von Karman’s equations to obtain particular stress and displacement functions respectively. Non-linear total potential Energy was formulated using Von Karman equilibrium equation and Ritz method was deployed in this formulation. A computer based program was developed using Matlab programming language to circumvent the challenges involved in solving the governing differential equations of thin rectangular plates. The developed program is capable of determining deflection and stresses at any point of the plate against the usual method of evaluating deflection at the center. The results obtained were compared with those of previous researchers The comparison made are only for SSSS, CCCC and CCCS plates. It was so because the remaining boundary conditions considered in this work have not been researched upon by previous researchers. From results obtained, the average percentage differences recorded for SSSS, CCCC, and CCCS plates for the present and previous studies are 4.01978%, 3.7646%, and 5.02% respectively. The percentage differences for the three plates compared are within acceptable limit of 0.05 or 5% level of significance in statistics. From the comparison made, it was obvious that an excellent agreement was observed in all cases thus indicating applicability and validity of the polynomial function and computer program for solving exact plate bending problems.