Foundation elements are most commonly constructed of reinforced concrete. As compared to the design of concrete elements that form the superstructure of a building, additional consideration must be given to concrete foundation elements due to permanent exposure to potentially deleterious materials, less precise construction tolerances and even the possibility of unintentional mixing with soil.
Flat slab system is an important division of concrete floor system. A civil engineer must know all the aspects regarding the flat floor system. Here, we have tried to gather various reading materials available in the web about flat slab floor system in one place. These materials are originally located at different websites. A civil engineer should study these lectures and materials for structural engineering acumen.
A flat slab is a reinforced concrete slab supported directly by concrete columns without the
use of beams. The benefits of using flat slab construction are becoming increasingly recognized. Flat slabs without drops (thickened areas of slab around the columns to resist punching shear) can be built faster because formwork is simplified and minimized, and rapid turn-around can be achieved using a combination of early striking2 and flying systems. The overall speed of construction will then be limited by the rate at which vertical elements can be cast. Flat slab construction places no restrictions on the positioning of horizontal services and partitions and can minimize floor-to-floor heights when there is no requirement for a deep false ceiling. This can have knock-on benefits in terms of lower building height, reduced cladding costs and prefabricated services.
“ClipConnTable” is a spreadsheet program written in MS-Excel for the purpose of analysis of steel beam end connections using double clip angles either welded or bolted to the beam web, and bolted to either the column flange, column web, or girder web. The connections may be subjected to end shear reaction and/or axial load. Specifically, all applicable “limit states” for the end connection analysis pertaining to the clip angles, bolts, beam web, column flange or web, and girder web are checked. The program is presented in a “tabular” format.
This program is a workbook consisting of four (4) worksheets, described as follows:
Doc – documentation sheet
Conn Table (Welded Clips) – Clip angles welded to beam web and bolted to support
Conn Table (Bolted Clips) – Clip angles bolted to beam web and bolted to support
Conn Table (Welded or Bolted) – Clip angles either welded or bolted to beam web and bolted to support
Program Assumptions and Limitations:
1. The most critical assumption used in this program is that all beam end connections are basically “full-depth”, utilzing as many vertical rows of bolts as permitted. See first page of each worksheet for outline of other assumptions used.
2. This program is basically a “tabular” format version of the “CLIPCONN.xls” program, and is best suited to analyze a large number of beam end connections in a very quick, efficient, and concise manner. (Note: The individual case worksheets in the “CLIPCONN.xls” program were used as “masters calculations” in the development of this program, and may be referred to for individual detailed calculations.)
3. Once the user has inserted the required input data in cells starting at A408 through F408 and down for each of the connections to be analyzed, then the user should copy the row of cells from G62 through the end cell of the particular spreadsheet (either CI408, CV408, or EG408) and “Paste Special” the formulas on down the worksheet to match the total number of connections to be analyzed.
4. This program follows the procedures and guidelines of the AISC 9th Edition Allowable Stress (ASD) Manual (1989) and the AISC 9th Edition Manual Vol. II – Connections (1992).
5. This program uses the database of member dimensions and section properties from the “AISC Shapes Database”, Version 3.0 (2001) as well as the AISC 9th Edition (ASD) Manual (1989).
6. This program assumes that the tension capacity for any “limit state” is reduced by the presence of shear. For allowable bolt tension in the presence of shear, the “interaction” (combined stresses) is handled directly by the AISC Code equations. For other “limit states” in combined stresses such as bolt bearing, gross and net shear and tension, and block shear and tension tearout, the effect of “interaction” is handled by use of the formula, P/Ra+(R/Rv)^2=1, as suggested from the following reference:
“Combined Shear and Tension Stress” – by Subhash C. Goel, AISC Journal, 3rd Qtr.-1986.
Thus, the reduction factor applied to the tension “limit state” capacity is = (1-R/Rv)^2.
where:R = actual shear end reaction; Rv = allowable shear capacity for the particular “limit state” considered
7. This program contains numerous “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc. (Note: presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell. Merely move the mouse pointer to the desired cell to view the contents of that particular “comment box”.)
Calculation Reference
AISC
This tool calculates the required SN. The Provided SN depends on whether this is new construction or a rehabilitation.
Please see the AASHTO 1993 Pavement Design Guide for guidance on rehabilitation design as well as calculations for ESALs.
General Description: Calculates the reinforcement required for a reinforced rectangular or square concrete footing with a rectangular or square columns at the centre of the footing, for flexure and checks 1 way and 2 way shear at the concrete column, using ductility class N reinforcement.
Limitations: For rectangular or square pads only, with no applied moment or horizontal forces. Does not design for shear reinforcement.
Codes/Theoretical Basis:
AS3600 – 2009 (Incorporating Amendment 1, 2010 )
Warner, Rangan, Hall & Faulkes, Concrete Structures, Longman, Melbourne, 1999
Foster, Kilpatrick and Warner, Reinforced Concrete Basics 2E, Pearson, 2010
Nomenclature: Symbols and notation as generally used in AS3600.
Input:
Yellow cells require data input by the designer
Geometry for the pad footing , etc
Concrete strength etc
Geometry of column etc
Applied actions and allowable bearing capacity
Area of tension reinforcement in both directions based on initial calculations and minimum reinforcement
Iterate if does not meet minimum design values
Where pink fill is used it alerts designer to options or information
Output:
Boxed cells with green background calculated automatically using formulae.
Footing weight, working load, total ultimate load, load factor and actual bearing pressure under the footing
Ultimate moment in each direction and initial area of reinforcing along with minimum reinforcement
Number, size and spacing of reinforcing bars
Maximum bending capacity in both directions Muo
Moment capacity fMu in both directions for the chosen reinforcement
Checks for minimum reinforcement
Checks one way and two way shear
Provides summary of the results
Feedback: For comments, corrections, suggestions or other feedback regarding this spreadsheet, please contact the CCAA
Calculation Reference
AS3600
Introduction
The first version of the Characteristic Load Method (CLM) spreadsheet (Brettmann and Duncan, 1996) was based on the CLM method (Duncan, et al., 1994) for analysis of single piles, and the Group Amplification Method (Ooi and Duncan, 1994) for analysis of pile groups.
That first version of the CLM spreadsheet was found to produce quite accurate results for single piles, but was found in many cases to overestimate deflections and bending moments for pile groups.
The revised spreadsheet described in this report uses the same method of analysis as the original
for single piles, but uses an improved method of analysis for pile groups.
Background
The characteristic load method (CLM) of analysis of laterally loaded piles (Duncan et al., 1994) was developed by performing nonlinear p-y analyses for a wide range of free-head and fixed-head piles and drilled shafts in clay and sand. The results of the analyses were used to develop nonlinear relationships between dimensionless measures of load and deflection.
These relationships were found to be capable of representing the nonlinear behavior of single piles and drilled shafts quite accurately, producing essentially the same values of deflection and maximum moment as p-y analysis computer programs like COM624 and LpilePlus3.0.
The principal limitation of the CLM method is that it is applicable only to uniform soil conditions.
The Group Amplification Method was developed by Ooi and Duncan (1994), to extend use of the CLM method to groups of piles and drilled shafts. Values of group amplification factors for deflection and moment were computed using the method developed by Focht and Koch(1973).
The original version of the CLM spreadsheet (Brettmann and Duncan, 1996) used the CLM method to calculate deflections and bending moments in single piles, and the Group Amplification Method to calculate deflections and moments for piles in pile groups. It was found that the original version of the spreadsheet resulted in accurate values of moment and deflection for single piles, but often over-estimated deflections and bending moments for the
piles in pile groups, as judged by comparison with p-y analysis programs and the results of field
load tests.
