Journal Jul 2023

Building typologies and seismic vulnerability attributes: A study on important buildings in Mandi district of Himachal Pradesh Yati Aggarwal, Sandip Kumar Saha

Most parts of the Indian Himalayan region are susceptible to severe earthquake shaking. Non-engineered construction practices in this region, due to lack of awareness/negligence of the stakeholders, are prevalent which may lead to disastrous consequences during any seismic event. For ensuring uninterrupted public services post-earthquake, it is utmost important to perform seismic vulnerability assessment of important buildings in this region to understand their expected performance during an earthquake. To conduct seismic vulnerability assessment of buildings at large, rapid visual screening (RVS) can be opted as a tool to quickly segregate them based on their expected performance. In this study, RVS of 108 important buildings (hospitals, educational institutes, and government offices) is performed in Mandi district of Himachal Pradesh, India. The observed building typologies for the important buildings and various vulnerability attributes in those buildings are presented here. Further, the surveyed important buildings are assessed based on different structural irregularities using three different RVS methods and it is observed that most of the surveyed buildings require detailed vulnerability assessment.

Seismic performance of RC tall buildings with transfer beam located in seismic zone II Pulkit Dilip Velani, Pradeep Kumar Ramancharla

Transfer elements are gaining popularity in tall buildings to support discontinuous vertical elements, such as columns or structural walls, that are required for the upper levels of the building while allowing for unobstructed spaces below. This configuration is essential in urban areas where space is limited and there is a demand for multiple functional uses, such as residential, commercial, and recreational, at lower levels. Such a structural form introduces stiffness and mass irregularity, which is undesirable from a design code perspective. Though such a configuration is widely accepted in other countries, viz., China, USA etc., its applicability to Indian conditions needs to be verified. With this motivation, the seismic performance of eighteen tall reinforced concrete (RC) residential buildings with transfer beams (TBs) located in seismic zone II is studied. Eleven ground motions are used to perform the linear time history analysis (LTHA), and three global parameters, namely base shear, displacement and inter-storey drift ratio (IDR), are used as performance indicators. The study found that the building performance under LTHA was satisfactory even after qualifying for several irregularities. Therefore, the TB feature can be allowed in seismic zone II and for zone III, IV and V; further investigation is needed before it is recommended.

Structural characteristics of reinforced concrete beams made of waste materials from ferrochrome industry Prasanna Kumar Acharya, Sanjaya Kumar Patro

The waste materials of various metal industries are well established as raw materials of concrete. But the ferrochrome industry’s waste materials are falling behind in this area due to a lack of knowledge. A dust waste herein named ferrochrome ash (FCA) and a solid waste herein named air-cooled ferrochrome slag (ACFS) are two such materials from the chrome-producing industry that possess good engineering properties. ACFS is hardly used while FCA is thrown off and that pollutes the environment. This paper investigates the impact of FCA as an alternative binder and ACFS as a substitute for coarse aggregate on some of the properties of normal and structural concrete. The mechanical properties and microstructure of concrete made using 40 % FCA as a binder and 100 % ACFS as coarse aggregate was noted as comparable to regular concrete. The load caring capacity, failure pattern, crack pattern and ductile behavior of reinforced cement concrete (RCC) beams that contained 40 % of FCA and 100 % of ACFS were observed higher than those of regular RCC beams. The inclusion of 40 % of FCA and 100 % of ACFS enhanced the first crack resistance, load caring capacity and deflection of beams 75, 25 and 36 % in comparison to that of normal concrete beams.

Performance of concrete made using sintered flyash lightweight aggregate-a review Brijesh Singh, Shamsher Bahadur Singh, Sudhirkumar V. Barai

Current work summarizes research done on potential of sintered fly ash lightweight aggregate based concrete and its suitability as an aggregate. The manuscript presents physical and chemical parameters of ingredients such as fly ash as well as binders adopted in manufacturing process covering effect of these materials on parameters related to pelletization like duration, angle of inclination and rotation speed and its subsequent effect of aggregate characteristics. The impact of sintering temperature and its duration on aggregate characteristics is also discussed. The physio-chemical and mechanical characteristics of sintered fly ash aggregate is briefly presented. The review of literature suggests that specific gravity and water absorption of sintered fly ash lightweight aggregate is low and high respectively as compared to conventional aggregate. The use of additives such as alkaline activators, styrene-butadiene rubber, quick lime etc. and additional treatments such as coating or vacuum impregnation has shown potential for reducing water absorption. The mechanical performance of sintered fly ash lightweight aggregate in concrete is different from normal concrete. Factors affecting compressive strength, flexural strength and modulus of elasticity apart from the characteristics of manufactured sintered fly ash lightweight aggregate are cement content, supplementary cementitious materials, additives used, treatment done to aggregate, aggregate content, shape index of aggregate etc. Studies have indicated no direct relationship between factors affecting concrete durability such as water absorption, mechanical perfromance, cement content, water penetrability and freeze-thaw resistance of sintered fly ash lightweight concrete. The sintering temperature, selection of binder, additives and internal curing plays vital role in quality of interfacial transition zone. Further research is needed to explain bonding mechanism between aggregate and matrix, shrinkage performance with increase in heating rate, relationship between factors affecting concrete durability such as water absorption, mechanical perfromance, cement content, water penetrability and freeze-thaw resistance of sintered fly ash lightweight concrete. The review suggests that sintered fly ash lightweight aggregate based concrete has great potential for its application in construction to obtain benefits such as reduction in dead load, improved thermal comfort and reduction in carbon footprint.

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