ce5510-advance structural concrete design-flat slab

Download CE5510-Advance Structural Concrete Design-Flat Slab

Post on 15-May-2017

228 views

Category:

Documents

2 download

Embed Size (px)

TRANSCRIPT

  • CE 5510 - 2004

    Advanced Structural Concrete Design

  • CE 5510 - 2004

    Flat Slab System

    Column Heads Division of Panels Deflection Crack Control Shear Arrangement of Reinforcement

  • CE 5510 - 2004

    Class Objectives

    Identify the types of slab construction, summarizing the advantages and disadvantages of each

    Explain the methods of analysis of slabsDetermine the design moments of one-way and two way

    slabs Design of flat slabs covering:

    division into strips, edge and corner columns, punching shear and provision of shear reinforcement

  • CE 5510 - 2004

    Recommended Reading James G. MacGregor, REINFORCED CONCRETE:

    Mechanics and Design, 3rd Ed., Prentice-Hall, 1997, Ch. 13 and 14.

    Allen, A. H., REINFORCED CONCRETE DESIGN TO BS8110 SIMPLY EXPLAINED, E&FN Spon, London 1988, Ch. 14

    The next few slides are from the Reinforced Concrete Council

  • CE 5510 - 2004

    Types of slabs

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

    Flat Slab

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

    Analysis of Slabs

    course

  • CE 5510 - 2004

    One-way spanning slab

  • CE 5510 - 2004

    Simplified

  • CE 5510 - 2004

    Two way action A rectangular panel supported on all four side

    Curvature more severe along lx Moment is short span higher

    Evaluation of moment is complex as behaviour is highly indeterminate

  • CE 5510 - 2004

    Consider two strips AB and ED at mid-span. Deflection at central point C is the same.

    4Deflection of udl beam = 5wl 384EI

    = kwl 4

  • CE 5510 - 2004

    4AB = k nAB ly

    4DE = k nDE lx

    nAB and nDE are portions of total load intensity transferred to AB and DE respectively.

    Since AB = DE ,

    4 4wl wl == nDE 4

    y 4

    nAB l 4 +x

    l 4 l + ly x y x

  • CE 5510 - 2004

    nDE > nAB

    Shorter span strip, DE, supports heavier portion of load and is subject to larger moment.

    Assumption supports are unyielding

    If the supports of the single panel is flexible, e.g. beams,columns, etc. the distribution of moment is more complex. Degree of stiffness of yielding support determines theintensity of the steepness of the curvature contours in thelx and ly direction and redistribution of moments.

  • CE 5510 - 2004

    Two-way spanning slab

  • CE 5510 - 2004

  • CE 5510 - 2004

    Mid Span Moments - corner supported

  • CE 5510 - 2004

    Approximate moment in one direction in slabs supported on columns at corners

  • CE 5510 - 2004

    Midspan moment - edge supported

  • CE 5510 - 2004

    Approximate distribution of moment in one direction in slabs with symmetrical supports on four sides

  • CE 5510 - 2004

    Moment

  • CE 5510 - 2004

    Restrained Corners

  • CE 5510 - 2004

    Table of Values

  • CE 5510 - 2004

    Table of Coefficients

  • CE 5510 - 2004

    Adjusted

  • CE 5510 - 2004

    Flat Slabs

  • CE 5510 - 2004

    Flat Slabs - Analysis

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

    Flat Slab - Moments

  • CE 5510 - 2004

    Widths

  • CE 5510 - 2004

    Distribution

  • CE 5510 - 2004

    Flat Slab Moment Transfer

  • CE 5510 - 2004

    U-Bars

  • CE 5510 - 2004

    Flat Slab Moment Transfer

  • CE 5510 - 2004

    What does it depend on?

  • CE 5510 - 2004

  • CE 5510 - 2004

    Edge Beams

  • CE 5510 - 2004

    Flat Slab - Shear

  • CE 5510 - 2004

  • CE 5510 - 2004

    Effective Shear Force

  • CE 5510 - 2004

    Deflection

  • CE 5510 - 2004

    Shear Reinforcement

  • CE 5510 - 2004

    Due to the limited depth special reinforcement are required involving the use of shear heads and anchor bars and wires.

  • CE 5510 - 2004

  • 2004CE 5510 -

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • 2004CE 5510 -

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • CE 5510 - 2004

  • DESIGN AND

    DETAILINGOF FLAT SLAB

    ESE SOEDARSONO HS27 FEBRUARY 2002

  • CONTENT

    Introduction Benefits Design Considerations Design Methodology Analysis of Flat Slab Detailing

  • INTRODUCTION

    What is a flat slab? a reinforced concrete slab supported directly

    by concrete columns without the use of beams

  • INTRODUCTION

    Flat slab Flat slab with drop panels

    Flat slab with column head Flat slab with drop panel and column head

  • INTRODUCTION

    Uses of column heads : increase shear strength of slab reduce the moment in the slab by reducing

    the clear or effective span

    Flat slab with column head

  • INTRODUCTION

    Uses of drop panels : increase shear strength of slab increase negative moment capacity of slab stiffen the slab and hence reduce deflection

  • BENEFITS

  • BENEFITS

    Flexibility in room layout Saving in building height Shorter construction time Ease of installation of M&E services Prefabricated welded mesh Buildable score

  • Benefits . . .Benefits . . .

    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

  • Benefits . . .Benefits . . .

    SAVING IN BUILDING HEIGHT

    Lower storey height will reduce building weight due to lower partitions and cladding to faade

    approx. saves 10% in vertical members reduce foundation load

    SlabSlab

    BeamBeam

    3.4m3.4m 2.8m2.8m

    ConventionalConventional

    SlabSlab

    3.2m3.2m2.8m2.8m

    Beam-FreeBeam-Free

  • Benefits . . .Benefits . . .

    SHORTER CONSTRUCTION TIME

    flat plate design willfacilitate the use ofbig table formwork toincrease productivity

  • Benefits . . .Benefits . . .

    SINGLE SOFFIT LEVEL

    Living RoomLiving Room Toilet

    Toilet ShowerShowerKitchenKitchenYardYard

    30307575

    2602603030 3030

    3030BalconyBalcony

    155

    155

    Flat Plate SlabFlat Plate SlabSingle Level CeilingSingle Level Ceiling

    Simplified the table formwork needed Simplified the table formwork needed

  • Benefits . . .Benefits . . .

    EASE OF INSTALLATIONOF M&E SERVICES

    all M & E services can be mounted directly on the underside of the slab instead of bending them to avoid the beams

    avoids hacking through beams

  • Benefits . . .Benefits . . .

    PRE-FABRICATED WELDED MESH

    Prefabricated in standard sizes

    Minimised installation time

    Better quality control

    Prefabricated in standard sizes

    Minimised installation time

    Better quality control

  • Benefits . . .Benefits . . .

    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

  • DESIGN CONSIDERATIONS

  • Design Considerations. . . .Design Considerations. . . .

    WALL AND COLUMN POSITION Locate position of wall to maximise the structural stiffness for

    lateral loads

    Facilitates the rigidity to be located to the centre of building

    Typical floor plan of Compass the Elizabeth

  • Design Considerations. . . .Design Considerations. . . .

    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 m3 per square metre

    this figure is considered to be economical and comparable to an optimum design in conventional of beam and slab systems

  • Design Considerations. . . .Design Considerations. . . .

    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, < L/250 or 40 mm whichever is smaller

    Limit set to prevent unsightly occurrence of cracks on non-structural walls and floor finishes

  • Design Considerations. . . .Design Considerations. . . .

    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

  • Design Considerations. . . .Design Considerations. . . .

    FLOOR OPENINGS

    No opening should encroach upon a column head or drop Sufficient