Seismic Performance of Masonry-Infilled RC Frames and Its Implications in Design Approach: A Review

Predicting the seismic response of masonry-infilled (MI) RC frames holds immense importance due to the significant influence of masonry on the structural performance. Despite numerous studies delving into the seismic behavior of these frames, their complex interaction of masonry infills and RC frame presents ongoing challenges for researchers, designers, and standards committees. Although numerous studies have been conducted to investigate the seismic behavior of masonry-infilled reinforced concrete frames, its complex behavior poses a challenge to researchers, designers, and the specification-making committees. In recent years, several national codes have been revised to include the estimation of the stiffness of reinforced and nonreinforced masonry walls and have provided guidelines for the modeling and analysis of structures considering MI. This article aims to provide a comprehensive review of how infilled masonry walls impact the seismic performance of RC frames, drawing comparisons with codal provisions. The focus lies on scrutinizing experimental, numerical, and analytical studies that explore in-plane and out-of-plane behaviors. Factors like masonry strength, stiffness, area of openings, stiffness degradation, energy dissipation capacity, and damage patterns are thoroughly examined. Key findings with critical implications are highlighted, shedding light on potential future research directions in this crucial field

Influence of ground-granulated blast-furnace slag on the structural performance of self-compacting concrete

In the last decades, the utilization of industrial waste like ground-granulated blast-furnace slag (GGBFS) has proven itself a great asset in the modern construction industry. Aiming at promoting the green housing initiatives, the present study focused on the study of the influence of GGBFS on the structural performance of self-compacting concrete (SCC). In the initial phase of the extensive experimental program, concrete cubes were prepared with the partial replacements of GGBFS (10%, 15%, 20%, 25%, and 30% with cement) and tested against the control mix in order to investigate the associated mechanical properties (compressive strength, tensile splitting strength, and flexural strength). At 20% GGBFS replacement, the optimum compressive strength was noted, and further addition of GGBFS caused a gradual decrease in the mechanical strength properties. This study further investigated the structural properties like axial load-displacement behavior and failure pattern of RC columns and flexural performance of RC slabs with and without the addition of GGBFS. SCC with 20% GGBFS demonstrated relatively better structural performance, causing the formation of smaller crack width/depth/length compared with the control mix. An empirical relationship was also proposed based on the experimental test results (in relation to the mechanical properties) in line with US and Indian standards code of practice

Quantification of Variability in Pond Ash Concrete and Its Effect on the Seismic Safety Performance of Reinforced Concrete Buildings

In this study, an attempt was made to use pond ash (PA), which is an industrial waste generated in power plants, as a replacement for fine aggregates (FA) in concrete. An experimental program was conducted on the mechanical properties (compressive strength, split-tensile strength, and flexural strength) of pond ash concrete. Five concrete mixes with varying proportions of pond ash replacing fine aggregates were designed to cast a total of 450 concrete samples. Thirty-two [two-parameter (2P), three-parameter (3P), and four-parameter (4P)] probability distributions were taken into consideration, and the statistical goodness-of-fit (GOF) tests Kolmogorov-Smirnov (KS), Kolmogorov-Smirnov-Lilliefors (KSL), Anderson Darling (AD), and chi-squared (CS) were carried out. The peak values for compressive strength, split-tensile strength, and flexural strength were observed at 20% replacement of FA by the PA. Based on the GOF test ranks, the most suitable probability distribution for modeling variations in compressive strength was the Cauchy distribution (2P). Similarly, Johnson-SB (4P), and Gumbel-Min (2P) were found to be the best distribution for the split-tensile strength and flexural strength, respectively. With an increase of pond ash substitution from 0% to 20%, there is a decrease in the probability of failure, and a further increase in FA substitution causes a decrease in concrete strength, which led to an increase in the probability of failure as shown by the fragility analysis

Enhancement of properties of recycled coarse aggregate concrete using bacteria

Due to rapid construction, necessity for raw materials of concrete, especially coarse aggregate, tends to increase the danger of early exhaustion of the natural resources. An alternative source of raw materials would perhaps delay the advent of this early exhaustion. Recycled coarse aggregate (RCA) plays a great role as an alternative raw material that can replace the natural coarse aggregate (NCA) for concrete. Previous studies show that the properties of RCA concrete are inferior in quality compared to NCA concrete. This article attempts to study the improvement of properties of RCA concrete with the addition of bacteria named as Bacillus subtilis. The experimental investigation was carried out to evaluate the improvement of the compressive strength, capillary water absorption, and drying shrinkage of RCA concrete incorporating bacteria. The compressive strength of RCA concrete is found to be increased by about 20% when the cell concentration of B. subtilis is 106 cells/ml. The capillary water absorption as well as drying shrinkage of RCA are reduced when bacteria is incorporated. The improvement of RCA concrete is confirmed to be due to the calcium carbonate precipitation as observed from the microstructure studies carried out on it such as EDX, SEM, and XRD

Investigation of cement mortar incorporating Bacillus sphaericus

Ureolytic-type bacteria has been used to improve the strength of cement mortar by the precipitation of calcium carbonate. In the present study Bacillus sphaericus has been used to improve the properties of cement mortar such as setting time, compressive strength and sorptivity. The setting time is found to be unaffected by the presence of bacteria. It is found that compressive strength at both 7-days and 28-days of mortar cube increases with the increase of bacteria concentration. At the optimum bacteria dosage of 107 cells/ml, the average compressive strength increases by 58% (at 7 day) and 23% (at 28 day) over the control specimen. The sorpitivity coefficient decreases as the concentration of bacterial cells increases. The mineralogy and morphology of the calcium carbonate precipitation have been tested by XRD and FESEM

Utilization of Bottom Ash and Pond Ash as a Partial Replacement for Sand in Cement Mortar and Concrete: A Critical Review

The rapid depletion of natural building materials is mainly caused by the exponential increase in construction operations. The need for and inevitability of finding alternative building materials to partially replace traditional materials in construction are unavoidable. In this study, the idea of using pond ash and bottom ash as a partial replacement of fine aggregates in concrete is examined, and the effects of pond and bottom ash on the fresh and mechanical properties of concrete are investigated, as reported in the literature. Being affected by the coal burning system, the chemical and physical properties of pond ash and bottom ash vary across various sources and years of investigation. Many experiments have shown that bottom ash and pond ash can be used in the right proportions to provide workability and increased strength of concrete. The idea of turning a variety of waste into wealth to conserve essential green space is backed by nearly every academic. Again, the increased use of fly ash (FA) and pond ash (PA) as an alternative to river sand will reduce river sand extraction and ensure the long-term stability of a green river ecosystem