Jul'20
The IUP Journal of Structural Engineering
Focus
Ansys allows flexibility of changing input parameters and results can be obtained quickly. In this paper, a real dam has been chosen and its cross-section is analyzed manually using a two-dimensional model. The finite element analysis uses rigid and flexible base conditions. Two sets of forces are considered: one set destabilizes the dam and the other set helps in stabilizing the dam body; and all relevant stresses developed must remain within the permissible limit. Further, reservoir full and also empty conditions are considered. One manual calculation has been performed, and it is compared with finite element analysis using ansys. The results indicate that stresses developed with consideration of flexible base are more than rigid base condition. When reservoir is empty, the direction of vertical acceleration does not have any significant role in stress distribution, but it has effect on displacement of the crest of the dam. The stresses developed around the opening of the dam provided for inspection are considerable and care must be taken in the design to strengthen these vulnerable areas.
The second paper, "Flexural Behavior of Metakaolin-Based Reinforced Concrete Beams", by J Saravanan, G Srinivasan and S Raja, studies RC beams cast with addition of metakaolin in concrete. The study compares beam's behavior cast with normal concrete and concrete mix with metakaolin and fly ash. The mix has metakaolin in different proportions varying from 0% to 25% and also 10% fly ash. The paper compares mechanical properties of two different concretes and optimum mix proportions with these admixtures. Further, flexural behavior of RC beams cast with these two concretes is also compared. The design mix for M30 concrete uses IS: 10262 (2009) and IS: 456 (2007). The test specimens such as cube, cylinder and beams were cast and cured, and two-point static loading was applied on the test beam. The deflections were measured at midpoint and at two loading points on the beam. Based on the results, metakaolin helps in enhancing early age and long age mechanical properties of cement paste/mortar/concrete. Partial replacement of cement with metakaolin reduces water penetration in concrete. Replacement with a combination of 10% metakaolin and 10% fly ash in concrete has good improvement in strength and deformation properties on the beam. The ultimate load carrying capacity of metakaolin and fly ash added concrete beam increases by 12% as compared to normal concrete beam.
The last paper, "Finite Element Analysis on Concrete Filled Steel Tubes (CFST)", by Pavan Gudi, Sanjay Deshpande, Sachin R Kulkarni and K P Thejaswi, determines strength development in Concrete Filled Steel Tube (CFST) section as compared to bare reinforced concrete section. It is believed that composite columns have better structural behavior than normal reinforced concrete or steel columns. Steel tube filled with concrete is a composite structure where both materials perform to their capacity under various load conditions. Its use is increasing in construction where heavy loads are to be resisted. The study uses ANSYS software to analyze this composite system. Circular, square and rectangular shape sections of the steel tube are considered for analysis. The parametric finite element analysis considers different diameter, size, length, depth, wall thickness of tube and also strength of various infilled concrete. For different geometric properties of steel tube and infilled concrete, ultimate load carrying capacity is calculated through finite element technique. The results are compared with the available experimental results. It is stated that finite element model predicts well the ultimate load as compared to available experimental results within the acceptable deviation.
Consulting Editor
An Analysis of Gravity Dam Using ANSYS
The section of gravity dam is so designed and shaped that its weight is sufficient to ensure stability against the effects of all imposed forces. The important complex factors that affect the stability of the dam are traditional calculation methods and mechanics of materials. These take a lot of time in the calculation and thus cannot give a more comprehensive analysis. So, the finite element simulation technology is widely used. Based on this, there exist many kinds of software of the finite element, and ANSYS software is one of them. In this paper, an effort has been made to apply various concepts to the actual size of "Bellary Nala Irrigation Project (Belagavi)" dam. The first step of simulation is aimed at validating the models developed by comparing them with manual results. By Finite Element Analysis (FEA), a two-dimensional Finite Element Model (FEM) of a gravity dam is proposed using Ansys APDL18.2. Dams with full reservoir and empty reservoir conditions are analyzed. Normal stress, principal stress, shear stress and deflection along the crest of the dam are observed. It is observed that when the reservoir is empty, the direction of vertical acceleration does not have a significant role in the stress distribution results, but it affects the displacement of the crest of the dam. The stresses developed with flexible base are more than that of rigid base. Also, when the reservoir is full, the openings in the dam induce higher stresses.
Flexural Behavior of Metakaolin-Based Reinforced Concrete Beams
The need for the study arises from the requirement to improve the overall utilization of mineral admixtures (Metakaolin (MK) and Fly Ash (FA)) in correct proportions of concrete. The effect of these two mineral admixtures towards the enhancement of the strength of the concrete needs to be researched. A simple mix design procedure is also to be developed for concrete considering the efficiency of two mineral admixtures. Thus the study evaluates the effect of partial replacement of cement by mineral admixtures (MK by 0%, 5%, 10%, 15%, 20%, 25% and fly ash by 10%) on the flexural behavior of reinforced concrete beams and compares it with the beams made with conventional concrete.
Finite Element Analysis on Concrete Filled Steel Tubes (CFST)
Concrete Filled Steel Tubes (CFST) consist of concrete filled inside the hollow steel tubes. The steel section acts as external reinforcement to concrete, thereby strengthening the section by increasing its resistance to shear, bending and torsion. The parameters such as material properties, geometry such as slenderness, D/t ratio, loading, boundary conditions and the degree of concrete confinement decide the performance of the CFST. As the load on a CFST column gradually increases, concrete and steel undergo changes in the lateral expansion. At lower strains, steel expands at a faster rate than concrete. At higher loads, steel transfers its longitudinal load to concrete and the expansion of concrete exceeds the expansion of steel due to change of stress from uniaxial to biaxial. The radial pressure induces hoop tension in the tube changing the state of stress from uniaxial to biaxial in the steel tube and from uniaxial to triaxial in concrete. A nonlinear Finite Element (FE) model is developed using the FE software package ANSYS to determine the ultimate load and axial deformation for circular, square and rectangular sections for different grades of infilled concrete.