For the first time in India, composite panels, a novel building component comprising of outer skins of cold formed steel (CFS) sheet with infill light weight cellular foam concrete has been developed to serve as an alternative to load carrying brick walls and floor/roof slabs. Experimental studies have been conducted to study the applicability of proposed lightweight panel to act as wall and floor/roof slabs. The tests revealed that the strength and behaviour aspects of these panels are found to be superior as wall and floor panels. Due to their high ductility characteristics, these panels have a huge potential in enhancing seismic performance/retrofit strategies for buildings and can be an alternative for load carrying brick walls and floor/roof slabs for affordable housing. As these panels are expected to have the high impact resistance due to their ductile behaviour, they can act as safety shelters during hazards and other natural disasters. The effectiveness of the shear walls is largely dependent on the panel-to-panel connection. The proposed work aims to identify their potential application as shear or core walls in a building and to develop the connections between wall-to-wall panels, wall-to-floor/slab panels and slab-to-slab panels and their performance assessment through experimental studies.
For heavy and industrial structures, hot-rolled steel beams and columns are connected by either welding or bolts. Welded connections are generally used for making a frame into a moment resisting frame. Such frames were damaged during Northridge (1994) and Kobe (1995) earthquakes at beam-column and base plate connections, but no collapse of steel buildings were reported. However, subsequently it was reported that the damage to the connections were so severe and the repair of these damaged steel buildings is impractical in terms of feasibility and economy. Though the level of damage in the structural element is prescribed according to the present approach of design methodology, which depends upon the severity of seismic action, there are no clear guidelines to obtain the cumulative inelastic action at connection level beyond which the damaged members have to be replaced. Hence, a new system is required, which can act as a mechanism, ensuring accumulation of the inelastic action for preventing collapse of structure and with ease of repair in the post-event of an earthquake.
Pre-engineered buildings (PEB) and structures in the housing sector is a urgent requirement of the day. The components in PEB are factory made and fabricated according to the requirement. Hence, the construction time required at site can be drastically reduced. In addition, the energy requirement and pollution levels is minimal compared to the conventional method. This advantage can be utilized to develop a residential framing system, which can be light weight, safe against the natural disasters, such as cyclone and earthquake. In view of this, the studies related to seismic behavior of cold-formed steel structural elements are taken up. A connection system was developed at CSIR-SERC with cold-formed steel (CFS) structural elements by using self-drilling screws through gusset plates. This connection system is easy to install at site without any supervision and does not require any special skill. The developed connection method was tested as a connection sub-assemblage under monotonic and cyclic loading. However, its performance has to be assessed through experimental and analytical studies on framing systems. In general, CFS structural elements and systems are classified as slender elements and as a result, Eurocode 8 suggests a response reduction in the range of 1.5 to 2, which is contrary to the values available in literature. This factor needs to be ascertained based on the response of the framing system with the developed connection.
Among the natural and man-made disasters, fire leads to the complete destruction of steel structures. Beam–column connections play a critical role in steel framed structure in controlling fire induced progressive structural collapse. While designing and analyzing a steel framed structure at ambient temperature, the connections between beams and columns are generally classified as either simple connections or moment resisting connections, based on their predominant bending moment capacity. Under the fire conditions, the behavior of the connections will be totally different owing to the presence of axial restraint offered to the connected members by surrounding structure and will collapse when the deformations reaches the critical limit. The analysis of beam-column connections in a steel frame building subjected to elevated temperature is often difficult due to the combined complexity of the material degradation caused by the thermal strains. There are very few reported research studies on steel beam–column connections behaviour under elevated temperature and there is a scope for further studies.
The service life of steel structures are affected by internal defects during manufacturing, which generally reduces the fatigue life of the structure. Repeated loadings cause fatigue failure in bridges, offshore structures, aircraft structures, etc. S-N curves are generally used to check the structural adequacy against fatigue loading. The existing codes of practice deal with only a particular configuration for all bolted connections. However, the strength and failure modes of these connections differ due to the nature of loading and configuration of connection. Hence, it is necessary to explore the effect of bolted connection configurations and associated failure path due to fatigue loading.