EVALUATION OF SEISMIC BEHAVIOR OF NON-STRUCTURAL ELEMENTS IN BUILDING

Abstract

Non-Structural elements (NSEs) are the components of building that do not participate in the load transfer mechanism. Past studies have revealed that the effect of seismic forces on NSEs is ignored and was considered only on the structural components. However, NSEs have a significant impact on buildings performance during events like earthquake. Certain NSEs such as multiple pipes, cable tray, firefighting system, HVAC duct system, etc. affect the behavior of building during a seismic event. In some places where earthquakes occur frequently, these NSEs cause severe damage to the building as they are not included in seismic design because they are considered non-structural. This study compares the lateral forces acting on NSEs obtained from Eurocode8 and IS 16700 showing that the lateral forces acting on NSEs increase with building height. Results reveal that IS16700 is underestimating the lateral forces acting on NSEs whereas lateral forces from Eurocode 8 are approximately twice as high as those from IS16700, thus adopting a more conservative approach. This comparison highlights the need for incorporating the effect of lateral forces on NSEs in Indian codes in a detailed manner to increase its focus on non-structural elements so that it aligns with best practices for improving the seismic safety. Critical structures such as hospitals should remain fully functional post seismic disaster therefore the seismic performance of NSEs is important in a building. These NSEs must be properly designed, anchored and installed in healthcare facilities to prevent damage to NSEs. Through an analytical study, this research underlines the importance of time period of structure and utility systems on the overall seismic design of NSEs, with a focus on healthcare units like hospital buildings. This study evaluates the seismic behavior of two NSEs – cable tray and multiple pipes supported on two different utility system (conventional and modular) within G+3 hospital building located in seismic zone V in India. Results reveal that modular support systems significantly reduced the lateral displacements by approximately 80 % to 90 % as compared to conventional systems. Moreover, the time period of cable tray is 0.14 seconds for the conventional support system whereas the time period of modular system is 0.017 seconds indicating higher stiffness and reduced risk of resonance. v | P a g e This time period has an inverse relationship with stiffness of the NSEs as a result of this more flexible elements experience amplified displacements and forces as compared to stiffer elements when subjected to seismic loading. International codes such as Eurocode 8 takes into consideration the dynamic behavior of NSEs by including effect of their time period of both utilities and building in lateral force calculation. However, Indian codes such as IS 16700 and IS 1893 lack provisions for considering the dynamic characteristics of NSEs such as the effect of time period in lateral force calculation. This study also reveals the critical role of utility support system selection in improving the performance of NSEs during earthquake and safeguarding the continuity of essential services in lifeline structures such as hospitals.