Influence of time period and derivation of critical storey limit for RC frame buildings using construction sequence method of analysis
Nehal Mahadevbhai Desai, Sandip Vasanwala
Department of Civil Engineering, Sardar Vallabhbhai National Institute of Technology, Surat, Gujarat, INDIA-395007
Construction sequence method of analysis;
Critical time period;
Critical storey limit;
Time-dependent properties of concrete
Construction Sequence Analysis (CSA) is a method that follows real-time onsite construction practices like construction sequence, sequential loading, and timing. Properties of concrete, like Creep and shrinkage are time-dependent properties of concrete, so it is crucial to determine the period up to which critical responses are received during a building’s life. This study observes the different responses of structural members seeing the long-term effect of concrete properties for up to 50 years, cohesive to the standard lifespan of RC structures in India. The study derives the most critical time during the entire life of the building using the CSA method. According to this study, 98% to 99% of the 50th-year responses are attained within 10950 days after applying live load. The study recommends analysing RC structures for 10950 days using the CSA method instead of ending at the time of live load application or continuing analysis up to 50 years. It is important to know the limit of total storeys above which the behaviour of vertical members becomes vulnerable in RC buildings. The study also determines the critical storey limit of RC moment frame building over which the CSA method must be utilised. Hence, this study uses the CSA and Linear Static Analysis method to analyse 12 RC building models of various beam spans and total storeys. The study concludes that the CSA method should be mandatory for buildings with more than nine stories.
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