03-07-2013, 02:35 PM
DESIGN AND DETAILINGOF FLAT SLAB
DESIGN AND DETAILING.pdf (Size: 3.93 MB / Downloads: 375)
INTRODUCTION
What is a flat slab?
•a reinforced concrete slab supported directly by concrete columns without the use of beams
Uses of drop panels :
•increase shear strength of slab
•increase negative moment capacity of slab
•stiffen the slab and hence reduce deflection
BENEFITS
•Flexibility in room layout
•Saving in building height
•Shorter construction time
•Ease of installation of M&E services
•Prefabricated welded mesh
•Buildable score
FLEXIBILITY IN ROOM LAYOUT
•allows Architect to introduce partition walls anywhere required
•allows owner to change the size of room layout
•allows choice of omitting false ceiling and finish soffit of slab with skim coating
BUILDABLE SCORE
•allows standardized structural members and prefabricated sections to be integrated into the design for ease of construction
•this process will make the structure more buildable, reduce the number of site workers and increase the productivity at site
•more tendency to achieve a higher Buildable score
OPTIMISATION OF STRUCTURAL LAYOUT PLAN
•the sizes of vertical and structural structural members can be optimised to keep the volume of concrete for the entire superstructure inclusive of walls and lift cores to be in the region of 0.4 to 0.5 m3per square metre
•this figure is considered to be economical and comparable to an optimum design in conventional of beam and slab systems
DEFLECTION CHECK
•necessary to include checking of the slab deflection for all load cases both for short and long term basis
•In general, under full service load, δ< L/250 or 40 mm whichever is smaller
•Limit set to prevent unsightly occurrence of cracks on non-structural walls and floor finishes
CRACK CONTROL
•advisable to perform crack width calculations based on spacing of reinforcement as detailed and the moment envelope obtained from structural analysis
•good detailing of reinforcement will
–restrict the crack width to within acceptable tolerances as specified in the codes and
–reduce future maintenance cost of the building