Numerous tragic incidents of progressive collapse of structures have been witnessed recently, many of them in regions prone to earthquakes, due to the spreading of a local failure throughout the entire structure. While seismic design aims primarily to mitigate the effects of earthquakes, its implications for structural integrity under extreme loading scenarios such as blast events or localized failures are less understood. This study aims to assess the vertical load resistance of different RC frame systems, i.e., Special Moment Resistant Frames (SMRF) and Ordinary Moment Resistant Frames (OMRF), under the effect of local failure. The study is conducted on 3D frame models that are seismically designed to meet the criteria pertaining to the chosen lateral load-resisting systems as per relevant Indian standards. To simulate the effect of local failure, several column-removal scenarios were considered. Global static nonlinear analysis was performed on each of these models to assess their robustness. Moreover, the results were also compared with the outcomes of the frame designed solely for gravity loads. The study showed superior performance of SMRF over OMRF systems. Findings from this research provide valuable insights into the interplay between seismic design criteria and progressive collapse resistance, aiding in the development of more robust and resilient structural systems in earthquake-prone regions.
The need for structural retrofitting and strengthening of aging infrastructure such as bridges, dams, power plants, industries, and buildings is continuously rising. Retrofitting existing structures to meet required capacities is a more sensible approach than demolition and rebuilding, as the latter generates substantial debris and waste, posing environmental concerns. Major issues affecting the durability and serviceability of structures include corrosion, faulty construction, lack of skilled labour, natural hazards, accidents, and excessive loading, among others. Various methods for retrofitting include section enlargement, steel plate bonding, additional supports, external post-tensioning, and FRP composite systems. Each of these methods has its advantages and disadvantages. A new-age composite material, particularly within the FRP family, is the Fabric Reinforced Cementitious Matrix (FRCM), also known as Textile Reinforced Matrix. This paper explores the purpose of the FRCM system, its advantages over conventional methods, and its typical applications in structural strengthening and retrofitting. FRCM combines the benefits of fabric reinforcement with a cementitious matrix, offering superior durability, flexibility, and ease of application. Its unique properties, such as high-temperature resistance, breathability, and adhesion to moist substrates, overcome the limitations of conventional FRP systems. Experimental studies discussed in this paper demonstrate the efficacy of FRCM in enhancing structural performance. Results show a 65
The reinforced concrete frame with steel bracing is the most reliable structural system for resisting lateral loads. In this study, a 10-storey RC building is considered for analysis. To investigate the effect of the bracing system, the seismic response of the unbraced building is compared with the building with a bracing system. The effect of the type of bracing system on the seismic performance of the building is also studied by using various bracing systems namely X-type, V-type, Inverted V-type, and diagonal type. For investigation, time-history analysis is carried out using ETABS 2021 software. The response quantities considered include maximum base shear, inter-storey drift, and top storey displacement. Results show that the bracing system helps in reducing the response of the building under seismic loading. The X-type bracing enhances the lateral stiffness and strength of the building more effectively than the other bracing systems.
Acceptance of bamboo as a building material is growing sharply due to its physical similarities with traditional structural elements. While strength and light weight make it a low-cost alternative to structural elements, bamboo is inherently sustainable. However, its use as a structural element is limited. The paper aims to study the strength and modulus properties of bamboo. A locally available bamboo identified as ‘Bambusa Vulgaris’ from the institute campus was collected and kept for sun-drying for about three weeks before preparing test specimens. Coupon specimens for strength and modulus; tension, compression, shear along with test specimens with and without notch for impact energy absorption were developed from bamboo culm adhering to relevant Indian and International Standards for the testing. These were tested using loading frame and impact testing machine. The ultimate tensile strength 166 MPa, and yield strength 124.5 MPa with an elastic modulus of 14.5 GPa derived for the dumbbell test specimen exhibiting ductile laminate failure. The compressive strength of test specimen was found to be 60 MPa with a height to diameter (h/D) ratio of 1. A shear strength of 148 MPa was achieved under single and 97 MPa under double shear on test specimens that sheared and elongated. Impact Energy Density for test specimens without a notch was evaluated to be 33.5 J/g/cm3, at par with steel material, demonstrating layer-by-layer fracture. These mechanical properties show good agreement with reported results for other species of bamboo.
Structural integrity of a structure is the ability of it’s components to hold together under the adverse action of rarely occurring excessive loading and aggressive environment condition. Any civil structure must be able to prevent catastrophic failure by undergoing deformation in a manner predicted during the design phase, thereby avoiding untoward incidents that can claim precious human lives and cause extensive damages. A promising technique to ensure that such catastrophic failures will be prevented is through the implementation of a robust Structural Health Monitoring (SHM) system. An efficient SHM system should be able to measure the structural deformation with minimal noise, analyse the output from the sensors installed, provide effective communication and enable the formulation of appropriate corrective action. This paper explains a methodology for integrating vibration based monitoring of large engineering structures based on operational modal analysis and Strain outlier detection in Internet of Things Platform. The methodology proposed can be applied to any engineering structure
