A Study of Sprinkler Activation for Waffle Beam Structure by Using Fire Dynamic Simulation

Abstract

This research aims to study the responsiveness of the ceiling sprinklers installation in perpendicular beam pattern or waffle slab structure using fire dynamic simulator (FDS) or Computational Fluid Dynamics (CFD) model. The researcher focuses on three major influences to analyze the sprinkler activation time including (1) heat release rate (2) sprinkler distance below ceiling positioning and (3) the sprinkler Response Time Index (RTI). In this research, the researcher chose to scope only one characteristic of waffle slab structure from the actual case. The simulation domain is limited to nine ceiling pockets sizing of 3.4 meter x 1.65 meter. The ceiling height (H) is 9 meters and beam depth (h_b) of 1.15 meter. In addition, the steady state ceiling jet that driven the automatic sprinkler activation are studied coupled with the theoretical correlation to explain smoke behavior in related to the specific ceiling pattern. The result shows that increasing of heat release rate or decreasing sprinkler RTI has rapid the activation of sprinkler whereas the sprinkler distance below ceiling factor generally extends the sprinkler response time in respect of limited heat release rate of 2,400 kW. The characteristic of the smoke plume acts as confined ceiling jet at Radius over Height (R/H) > 0.34 in terms of temperature and R/H > 0.11 in terms of gas velocity.