Journal Jun 2023

Modifications proposed in IS: 13920 (2016) regarding shear wall design following the limit state design philosophy of national and international standards Anasuya Mondal, Santanu Bhanja

In shear walls, the vertical reinforcements being generally uniformly distributed over the section are represented by a continuous steel plate along the length of the wall. Hence, stress blocks for steel in tension and compression with the stress block of concrete are used for solving the equilibrium equations. For checking the safety of the sections which are simultaneously subjected to flexure and axial compression like columns, interaction charts are necessary. The present Indian Standards do not provide such design aids or tools for design of shear walls. Rather some expressions based on simplified assumptions which are not fully conforming to the requirement of LSM of design as per IS: 456 (2000)[1] are provided. The present work makes a humble effort to overcome the short comings of the design methodology for shear walls as prescribed by IS: 13920 (2016)[3]. force moment (P-M) interaction diagrams for different grades of structural concrete permitted by IS: 456 (2000)[1] and four grades of high yield strength deformed (HYSD) steel namely Fe415, Fe500, Fe550, Fe600 have been proposed conforming to the fundamentals of limit state method (LSM) of design as per IS: 456 (2000)[1]. In addition, P-M interaction charts have been prepared conforming to the requirements of IRC: 112 (2020) [29], which is having similar requirements as per EN 1992-1-1 Euro Code: 2. The moment capacities calculated from two sets of P-M interaction charts prepared as per IS: 456 (2000)[1] and IRC: 112 (2020)[29] have been compared with the corresponding values obtained from the closed form expressions available in IS: 13920 (2016)[3]. The discrepancies have been clearly highlighted. IS: 456 (2000)[1] is on the verge of revision whereby significant changes are likely to be introduced. It is most likely that the modified standard will be in line with the RC design provisions of IRC: 112 (2020)[29], which are in line with international standards. It may be stated that the proposed P-M interaction charts which are more convenient to use than closed form equations, cater not only to the present version of IS: 456 (2000)[1] but are expected to find useful application for the revised version of the standard also.

Fragility assessment of non-ductile RC frames subjected to pounding R. Sinha, B. N. Rao

Out-of-phase vibrations of series configured structural systems subjected to ground shaking scenarios lead to collisions between adjacent buildings. Such collisions, known as structural pounding, can lead to devastating failures. This study aims to analyze the effects of structural pounding on the displacementbased demands of a non-ductile reinforced concrete frame against a stiffer frame for floor-to-column interactions. The investigation uses the empirical cumulative distribution function to derive fragility curves for estimating pounding risks. It is inferred that such a fragility curve generation technique proves to be accurate and computationally economical for the analytical risk estimation of pounding.

Experimental study on performance of concrete with surface treated C&D waste aggregate Aman Jangir, Praveen Kumar Agarwal

In this experimental study, main focus is improvement of construction and demolished (C&D) waste aggregate performance and quality, especially decreasing water absorption and improve interfacial transition zone (ITZ) with reducing cost. M25 grade concrete is taken in this experiment study and natural coarse aggregate were replaced with untreated C&D waste coarse aggregate and treated C&D waste coarse aggregate in different percentages. Basic tests were done on untreated C&D waste aggregate, treated C&D waste aggregates and compared with natural aggregate. Similarly, the properties of concrete containing three different types of aggregates were evaluated to determine their characteristics. The observed results show that the utilization of treated C&D waste aggregate improves the mechanical and physical properties.

Measurement of durability properties of unitary and binary mortars containing supplementary cementitious materials Niragi Dave, Vaishali Sahu

Sulfate attack is a deteriorating phenomenon in concrete and is responsible for strength reduction, development of cracks, and disintegration of concrete and volume expansion. Use of supplementary cementitious materials (SCM) has been effective in improving the sulphate resistance and is dependent on the characteristics of SCM used in concrete. In the present investigation low-carbon metakaolin (MK) has been employed as a supplemented cementitious material to prepare cement mortars. Sulfate attack testing in sodium and magnesium sulfate solutions has been performed. The usual test method has been used to determine the sulfate resistance of these combinations to expansion and loss of compressive strength. In mortars, the water-cementitious content (w/cm) ratio and Metakaolin dose has ranged from 0.45 - 0.55 and 0 - 10 % (by mass), respectively. Mortars with w/cm = 0.45 displayed negligible degradation, signifying that they are sulfate resistant. The control mortars showed higher degradation than the Metakaolin mortars having w/cm = 0.50 to 0.55. The sulfate resistance of mortars reduced with increase in Metakaolin dose at any given w/cm ratio. While both sodium and magnesium sulfate degraded the specimens, the former resulted in enhanced expansion of the specimens studied, whilst the latter resulted in considerable compression strength loss. Metakaolin mortars had a sulfate resistance that was comparable to that of silica fume mortars.

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