Pyramid of Meidum

shed 250,000 tons of limestone outer casings

Seven Wonders

of the Ancient World

Typical Pyramid Pyramid at Meidum

Mexico •  Alameda buildings •  Palace of Fine Arts •  National Theater •  Lake Texcoco

Design Decisions

•  location •  size and shape of building •  weight of building •  flexibility of construction •  shallow or deep foundation

Foundation Location and Design

•  location of good bearing soils for foundation design

•  liquid or plastic limits of soil

•  percolation rate of soils

•  location of underground water

•  frost susceptibility –  bottom of footing is 12” below Average Frost Depth –  data for frost is localized –  Saint Paul average frost depth is 4’-0”

•  problems from underground surprises

Why get a Soil Test?

•  layers of soils •  load-bearing capacity of the soil •  stability (clay may swell with water) •  drainage characteristics

Soil test information

•  Frictional Soils grain size grain shape

–  G=gravel bulky coarse/silica

–  S=sand sands

–  M=silt flake loams

•  Cohesive Soils grain size grain shape

–  C=clay plate-like

–  O to PT organic peat

Soil Classification and Grading larger sm

aller

Soils Test

•  liquid limit – the water-content point at which the soil passes from a plastic state to a liquid state

•  plastic limit – the water-content point when soil loses its plasticity and begins to behave as solid.

Foundation Types

SHALLOW FOUNDATIONS

•  Slab on Grade

•  Grade Beam

•  Perimeter Foundation Wall / Spread Footing

•  Column Pads

•  Raft or Mat

DEEP FOUNDATIONS

•  Piles (driven)

•  Caisson (bored and poured)

bigger buildings

•  deep foundations

–  caissons (drilled piles or piers)

•  cast-in-place concrete •  2’-6” minimum diameter •  base bearing condition

•  deep foundations

–  pile foundation •  end-bearing or friction piles •  pile caps •  tie beams

DEEP FOUNDATIONS

Piles (driven)

Caisson (bored and poured)

DEEP FOUNDATIONS

Piles (driven)

Caisson (bored and poured)

Photograph taken ca. 1897 Recent Photograph

The Problem

The Problem

Differential Settlement

Foundation Types

SHALLOW FOUNDATIONS

•  Slab on Grade

•  Grade Beam

•  Perimeter Foundation Wall / Spread Footing

•  Column Pads

•  Raft or Mat

DEEP FOUNDATIONS

•  Piles (driven)

•  Caisson (bored and poured)

•  isolated footing

•  strip footings

•  continuous footing

•  grade beam

•  cantilever, strap footing (tie beam) or combined footings

•  mat or raft foundations (also floating foundations)

Simple shuttering for pad foundations is made up on site.

The reinforcing cage and some of the formwork for a foundation

This is one of two reinforced concrete bases which will carry the building's main shear frame.

Steel columns in the building's frame are fixed to their foundations by bolts which have been precast into the foundations.

This is the base of one of the legs of the shear frame

The bottom of the leg is bolted onto the top half of the bearing assembly

The bottom half of the bearing is fixed to the concrete foundation

Here's a view of the main shear frame. The two inner 'legs' of this massive frame are mounted on bearings.

Steel shims are used to get the steel columns to the correct level - the gap will eventually be filled with a high strength grout.

After just two days work the steel frame for the ground floor of Building C is taking shape. The eastern and southern sides of the frame are almost complete while the north west corner is still to be erected.

Portland Square

SHALLOW FOUNDATIONS Slab on Grade Grade Beam Perimeter Foundation Wall /

Spread Footing Column Pads Raft or Mat

SHALLOW FOUNDATIONS

Perimeter Foundation Wall / Spread Footing

Column Pads

Foundation Types rule of thumb for sizes

•  Column Pads –  size for preliminary design is 3’ X 3’ X

12” with #5 bars and anchor plates s connect to bars

•  Perimeter Foundation Wall / Spread Footing –  footing depth is equal to thickness

of wall (varies with building load, soils)

–  footing width is twice thickness of wall

–  stepped footing for change in ground’s slope to remain below frost

frost line

Masonry Wall

Stud Wall

Thickened Edge Slab

Not a frost footing

wall footing column footing

The foundation runs under all the loadbearing walls.

In this example this includes the external walls……

Strip Foundations

A typical modern detached house will, where possible, sit on strip foundations. Providing the ground is suitable, this is the simplest and cheapest form of foundation.

and the internal walls

The foundation supports all the loadbearing walls.

This includes the external cavity walls (275mm wide), and the internal walls (100mm wide).

The internal walls are loadbearing because they help support the 1st floor joists.

The line of the foundations can be highlighted using hydrated lime - here the trench centre line is being marked.

On some sites you will find both sides of the trench marked.

Digger buckets are available in various widths to suit specific trenches.

Boning rod

Site rail

Site rail

Correct depth can be checked with a Level and staff.

When trenches have been excavated they should be checked for ‘square’ etc - mistakes can be expensive once the concrete has been poured.

The trenches should be cleaned out and ‘bottomed-up’ (cleaned out and loose material removed), ready for inspection.

In traditional strip foundations the services cross the trench above the concrete - in trench fill they cross through it.

duct

Traditional strip

Trench fill

Trench fill

Foundation footers for this basement have been completed and the rebar are in place.

The wall frames have been erected and carefully pinned securely into place. The concrete has been poured and the walls are curing.

Poured walls have cured so that the frame panels may be removed. The wall frames are being unpinned and the panels taken away.

Removal of the poured wall frame panels is complete and the walls are allowed to finish curing.

Balance Assoc. Cabin at Elbow Coulee, Washington State

D o

w n

h i

l l

Warehouse: 15th Ave and 8th St

Lucas Deslauriers . Christopher Farrar . Rachel Hilvert . Ryan O’Malley . Stephanie Wichner

Group 7

Fault Genesis

CB

A

CB

A

B

A

B

A

Existing Structure Photos

C

B

A

C

Existing Structure Photos

BA

Existing Structure Photos

C

B

Existing Wall Elevation

Existing Wall Elevation

wood cast iron