Optimal Configuration of Diagrid and Outrigger Structural Systems for Tall Buildings

Abstract: Demand for High Rise structures has become so exponentially high that effective and advanced form of structural systems needs to be studied in detail so as to choose the best suitable structure in a given scenario. Structural system for a tall building should be configured so as to maximize its structural efficiency. The present study aims to evaluate the optimal configurations of structural systems- Diagrid and Outrigger for tall buildings. A 42 m x 42 m size regular floor plan is considered for analysis. Analysis of diagrid and outrigger structural system for tall steel building of 60 storey subjected to lateral loading is carried out in E-tabs software by considering the possible variation in both the systems (i.e. Angles for diagrid system and topology for outrigger system). Response spectrum analysis for earthquake loading and gust factor method for dynamic along wind response is considered for analysis of structure. Comparison of analysis results is presented in terms of top storey displacement, inter-storey drift, structural steel quantity and first mode time period. Based on the analytical results, the optimum configuration of diagrid and outrigger structural system is identified. It was found that the diagrid system having variable density and conventional outrigger with belt-truss having X topology gives optimal configuration for respective systems. It is also concluded that the performance of the diagrid structural system surpasses the Outrigger structural system.

Keywords: Diagrid, Conventional Outrigger, Virtual Outrigger, belt-truss, Topology, Structural System, Cost efficiency.