• Smitha Gopinath

      Articles written in Sadhana

    • Residual strength evaluation of concrete structural components under fatigue loading

      A Rama Chandra Murthy G S Palani Nagesh R Iyer Smitha Gopinath B K Raghu Prasad

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      This paper presents methodologies for residual strength evaluation of concrete structural components using linear elastic and nonlinear fracture mechanics principles. The effect of cohesive forces due to aggregate bridging has been represented mathematically by employing tension softening models. Various tension softening models such as linear, bilinear, trilinear, exponential and power curve have been described with appropriate expressions. These models have been validated by predicting the remaining life of concrete structural components and comparing with the corresponding experimental values available in the literature. It is observed that the predicted remaining life by using power model and modified bi-linear model is in good agreement with the corresponding experimental values. Residual strength has also been predicted using these tension softening models and observed that the predicted residual strength is in good agreement with the corresponding analytical values in the literature. In general, it is observed that the variation of predicted residual moment with the chosen tension softening model follows the similar trend as in the case of remaining life. Linear model predicts large residual moments followed by trilinear, bilinear and power models.

    • Low velocity impact behaviour of ultra high strength concrete panels

      Smitha Gopinath R Ayashwarya V Ramesh Kumar Prabhat Ranjan Prem A Rama Chandra Murthy C K Madheswaran R Nagesh Iyer

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      This paper presents the results of an investigation carried out on Ultra High Strength Concrete (UHSC) panels subjected to low velocity projectile impact to assess impact resistance. UHSC panel of size 350 × 350 mm and thickness 15 mm is studied under drop weight impact loading for three different pre-determined drop heights ranging from 100 mm to 300 mm. The response of UHSC panel in terms of acceleration vs time is obtained experimentally. Numerical model has been developed to simulate the impact behaviour of UHSC panel. The Brittle cracking model is used to simulate the behaviour of UHSC panel under impact loading and to perform parametric studies by varying the volume fraction of steel fibres.

    • Investigations on the influence of matrix and textile on the response of textile reinforced concrete slabs under impact loading


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      Textile Reinforced Concrete (TRC) is gaining its popularity as a construction material. It is essential to investigate new materials to quantify its expected structural performance and integrity. The purposed study is to investigate the influence of material type and volume fraction of textile and type of matrix on theimpact behaviour of textile reinforced concrete slabs. Both glass and basalt textiles were used in the investigations. Based on the investigations, it is concluded that the type of binder influences the impact resistance at first crack as well as the delamination possibility. Glass textile reinforced concrete slabs show more displacement and more residual capacity compared to basalt textile reinforced concrete slabs. With increased number of layers, the basalt textile reinforced concrete slabs exhibited decrease in impact resistance due to delamination.As energy level increases, glass textile reinforced slabs show increase in peak displacement whereas basalt textile reinforced concrete slabs show a decrease. The investigations reported will be useful for extending the knowledge of textile reinforced concrete for various impact resistant applications.

    • Synergy of hybrid textile reinforced concrete under impact loading


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      The article presents a novel hybrid concrete composite which is produced by combining glass and basalt textiles for achieving enhanced impact resistance compared to their independently reinforced counterparts. A full factorial analysis was performed to determine the synergy of two types of textiles and theircombination on the impact strength and energy absorption. The two levels of key factors were considered for analysis such as the type of textile and impact energy level, and variance. The influencing parameters showed statistical significance with more than a 90% confidence level concerning impact resistance and energyabsorption. The combination of two textiles showed the highest impact resistance irrespective of the energy levels, compared to the use of single textiles. The findings demonstrated that the energy absorption of hybrid textile reinforced concrete is not significantly enhanced with the increasing level of impact energy. At the high levels of impact energy, in comparison to the hybrid textile reinforced concrete slabs and basalt textile reinforced concrete, more energy is absorbed by the glass textile reinforced concrete slabs. Thus, in hybrid textile reinforced concrete, it is indicated by the failure pattern that combining basalt and glass textile influences the degree of local failure. Therefore, this research emphasizes on the synergy to customize and optimize textile reinforced concrete with superior impact resistance and energy absorption for the protection of structures in theevent of impact loading.

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