Feasibility of Foundation and Flooring Systems for Child Care Centre Project

CONSULTANT’S REPORT ON THE FEASIBILITY OF THE AVAILABLE FOUNDATION AND FLOORING
SYSTEMS OPTIONS
PREPARED BY
DATED
LECTURER
DEPARTMENT

1. EXECUTIVE SUMMARY
Foundations and flooring systems in a building are the most critical elements that must properly be designed. This must follow both
local and national construction codes. For example, we must first establish the type of soil to be encountered so that the type of
foundation selected will match with the prevailing geotechnical information. The report entails technical details on the feasibility
study for Child Care Centre project. Specifically, it provides technical details on the foundation and flooring options.
Project Technical details
The site to be developed is located in Charlestown NSW Australia on the North eastern side of pacific highway, sandwiched by
Kahibah road and George Street. It is generally scrub vegetation with a few trees along the site edges. The topography is gently
sloping with predominant mix of clay and sandy soils. The ground slopes towards the Karibah road in the South East region. The
development entails construction of Child care centre project; a low rise commercial building. The architectural design was done by
Daryl Jackson Robindyke Pty Ltd and therefore, a bulk of this report was derived from the designs.

Figure 1: Basic plan of the proposed childcare development (from the architectural drawings)
2. FOUNDATION SYSTEM
(a) Characteristics of the buildings and site conditions
It is generally scrub vegetation with a few trees along the site edges. The topography is gently sloping with predominant
mix of clay and sandy soils. It slopes towards the Karibah in the South East region. However, it is surrounded by other
buildings from all sides hence making it difficult to maneuver with construction materials. From the geotechnical

information, rocks and cohesive soils are predominant in Charlestown square. The average soil bearing capacity is between
75 and 150 kN/m2. Due to the nearby growing trees especially in the western side of the building site, cracking of the
walling element due to moisture absorption is inevitable. There are also possible vibrations due to nearby traffic hence this
must also be considered during foundation design and selection. Settlement due to ground water change is also likely to
occur. In soft clay, if the building loads are unmatched, sinking is inevitable and this may cause catastrophic failures such
as overturning.
(b) Comparison of the alternative solution methods
Foundation is the lower portion of a building which rests on the earth and is normally designed to carry both live and dead
loads of the walling element while adequately resisting some movements due to soil condition in which it is established. The
substructure therefore is that portion of a building sunk in the ground while the substructure is erected outside such that load
path is from the roof via the walling element into the foundation. The live loads could be due to wind actions or soil actions
among others like rain water, snow and occupants while the dead loads are imposed by the weight of the roof and walling
elements. Commonly, for residential low rise buildings (like the child care centre development), the best alternative
foundations to consider are either pad or strip foundation. Hence these two are reviewed and the best match will be selected.
From the architectural drawings provided, it can be deduced that the buildings is low rise hence most loading is transmitted
horizontally. However, a strong foundation must still be built.

(i) Pad foundation
This is the most appropriate foundation system for both medium and low rise building structure as each foundation is
independent of each other and they can have different designs catering for the various imposed loads. This makes them ideal
for both symmetrical and unsymmetrical floor plans and building shapes. The load in this case is transferred directly from the
columns into the footing and in some case; more than one column can reside on a single pad footing. This type of footing is
applicable in a wide variety of structural systems ranging from ordinary moment resisting frames and portal frames to shear
wall building frames. This therefore means that they can be used on almost every building material from concrete to stone.
Notably, however, the area in which the building is to be seated is in one of the streets of Charlestown and from various soil
tests carried out, it reveals that clay soils could be dominating implying that the soils are verily reactive (this is categorized as
class H according to AS 2870 and AS 1726) hence need to integrate another foundation type to accommodate the changing soil
properties like moisture content. AS 2870 provides further technical requirements for this kind of foundation. Nevertheless,
pad footings are only applicable in providing support to the columns hence it is normally restrictive to localized vertical
support. In the drawing plan, position of piers to be sunk provides a rough indication of the exact location of these pad
foundations as they are linked directly. Besides, safeguards on shear and bending moments will only be sufficient if the
concrete mix strength and the reinforcement are appropriately done (Murty et al, 2002). Area of the foundation often depend
on load to be transmitted, bearing and shear strength of the soils, thickness, exaction method adopted and the concrete
formwork.

Table 1: Comparing Pad and Strip foundations
PAD FOUNDATION STRIP FOUNDATION
Ideal for symmetric plans since it is isolated Safeguards against shear and bending
Ideal for moment resisting frames and portal frames Accommodates swelling and shrinkage of reactive soils
Restricted to localized vertical supports Firm structure provisions