Foundation
Page 1: Major Building Parts
Foundation Size Determination
Determined by:
Structure and size of building it supports.
Bearing capacity of the ground supporting it.
Permeability
The property of soil that permits water to percolate through it is called Permeability.
Components of a Building
Every building consists of two basic components:
Super-structure
Examples: Crane tower, Columns, Girders, etc.
Sub-structure or Foundation
Examples include Piles, Rock, etc.
Page 2: Foundation Purpose and Importance
Safe Bearing Capacity
The maximum pressure that soil can bear without shear failure is termed Safe Bearing Capacity.
Introduction
The foundation of a building is in direct contact with the ground and transmits loads to the ground.
Every building requires a foundation.
Purpose of Foundation
Distributes the load over a large bearing area to bring the load intensity within safe limits.
Prevents differential settlement by loading the bearing surface uniformly.
Prevents lateral movement of supporting materials.
Provides a level and firm bed for building operations.
Increases overall stability of the structure.
Importance of Foundations
Foundations are crucial for safety; without proper foundations, buildings may be unsafe and aesthetically unpleasing.
Requirements of Foundation
Structural stability
Functionality
Durability
Economy
Factors Affecting Foundation Design
Construction requirements.
Soil types and groundwater table conditions.
Site conditions and environmental factors.
Page 3: Types of Footings
Sloped Column Footing
Simple Wall Footing
Simple Column Footing
Stepped Wall Footing
Stepped Column Footing
Page 4: Types of Foundations
Basic Types
Shallow Foundation
Located below the lowest part of the structure near ground level, transferring load directly to soil.
Suitable when stable soil with adequate bearing capacity occurs near the surface.
Requirements of Shallow Foundation
Suitable soil bearing capacity.
Undisturbed soil or engineered fill.
Types of Shallow Foundation
a) Spread Footing (Open Trench Foundation)
b) Combined Footing
c) Mat/Raft Foundation
Page 5: Spread Footing Details
Characteristics of Spread Footing
Wider base to distribute weight and prevent instability.
Common in residential buildings.
Types of Spread Footings
Single Footing for Column
Enlarged foundation area for columns.
Stepped Footing for Column
Designed for heavily loaded columns, includes steps.
Sloped Footing for Column
Non-uniform thickness with a slope.
Wall Footing without Steps
Includes a masonry wall with a concrete base.
Stepped Footing for Wall
Masonry wall with stepped footing.
Page 6: Isolated Spread Footing
Isolated Spread Footing Details
Dimensions: 3" x 3"
Reinforcement: R.C.C. Column with concrete base (P.C.C. 1:4:8)
Include sand filling and grade beam details.
Page 7: Eccentric Spread Footing
Eccentric Spread Footing Details
Dimensions: 4" x 2'-7"
Reinforcement details for grade beam, RCC column, and bitumen wrapping included.
Page 8: Isolated RCC Footing
Isolated RCC Footing
Details on construction for isolated RCC footings.
Page 9: Spread Footing Variants
Variants of Spread Footings
Rigid Spread Footings
Flexible Spread Footings
Centric Rigid Spread Footing
Eccentric Flexible Spread Footing
Page 10: Layout Plan for Footing
Layout Plan
Detailed dimensions and positions for footing layout.
Represented with specific identifiers (e.g. B1, C1).
Page 11: Combined Spread Footing
Combined Spread Footing Types
Rectangular Combined Footing
For columns of equal loads; center of gravity aligns with centroid.
Trapezoidal Combined Footing
For columns with unequal loads.
Combined Column-Wall Footing
Required for both wall and column supports.
Page 12: Combined Footing Details
Dimensions and Reinforcement
Details of combined footing dimensions.
Reinforcement with RCC columns and gravel fill.
Page 13: Raft Foundation
Raft Foundation Characteristics
Thick concrete slab that covers the entire contact area of the structure.
Reinforced with steel, with bars running normal to each other for load distribution.
Suitable for higher loads and minimizing settlement.
Types of Raft Foundation
a) Solid Slab System
b) Beam Slab System
c) Cellular System
Page 14: Raft Foundation Usage
Raft Foundation Usage
Used for light and medium structures with unevenly distributed loads.
Illustrations showing slab with beams and solid slab raft.
Page 15: Deep Foundation
Purpose of Deep Foundations
Transfer building loads deep into the earth.
Types of Deep Foundations
Pile Foundation
Pier Foundation
Caissons or Well Foundation
Page 16: Pile Foundation Characteristics
Pile Foundation
Utilizes vertical members (timber, concrete, steel) for transferring loads to lower levels.
Types of Piles
a) End Bearing Piles
b) Friction Piles
c) Compaction Piles
Page 17: Pile Foundation Structure
Pile Foundation Structure
Reveals effective distribution of load through R.C.C. columns and grade beams.
Page 18: Pile Types Explained
Pile Types
End Bearing Piles - Transfer loads through water or soft soil to hard strata.
Friction Piles - Use skin friction to carry loads deep.
Compaction Piles - Compact loose soil for better bearing capacity.
Page 19: Pier Foundation
Pier Foundation Description
Consists of a cylindrical column supporting large loads, transferring them to more stable strata.
Page 20: Well Footing
Well Foundation
Box-like structures sunk into land or water, used for major works (bridges, docks).
Page 21: Construction of Foundation
Key Activities in Foundation Construction
Site Preparation
Site Layout
Excavation
Pour Footing
Pour Slab on Grade
Pour Concrete Foundation Walls
Page 22: Formwork Construction
Formwork and Concrete Tasks
Construct formwork where needed.
Install reinforcement (rebar) for footing.
Pour concrete for footings and smooth finish.
Page 23: Foundation Reinforcement
Reinforcement Details
Dimensions and reinforcement strategies for foundation footings.