Foundation System PDF

MAPUA UNIVERSITY Foundation System Building Systems Design GROUP 1 ANG, J.; DIMBLA, N.; GUMPAL, R.; NATAVIO, K.; RIVERA, K.; ROBLES, C. Overview Importance of Soil 1 Introduction 6...

MAPUA UNIVERSITY Foundation System Building Systems Design GROUP 1 ANG, J.; DIMBLA, N.; GUMPAL, R.; NATAVIO, K.; RIVERA, K.; ROBLES, C. Overview Importance of Soil 1 Introduction 6 Mechanics 2 Foundations Overview 7 Soil Testing 3 Types of Foundations 8 Field Exploration 4 Foundation Failures 9 Conclusion 5 Soil Considerations 10 References Introduction In engineering, a foundation is the lower part of a structure that transfers its load to the ground, ensuring stability and support. It distributes the building's weight evenly, prevents excessive settlement, and anchors the structure against forces like wind, earthquakes, and soil movement. Introduction Adaptation to Soil Durability and Conditions Longevity Support for Safety Assurance Additional Loads Foundations Overview Shallow Foundation Deep Foundation a type of foundation that is constructed near the a type of foundation that is constructed at a surface of the ground, typically at a depth of less greater depth, typically deeper than 3 meters (10 than 3 meters (10 feet). It is used to support feet), to transfer the load of a structure to stronger, structures where the load-bearing capacity of the more stable soil or rock layers that are located soil near the surface is sufficient to handle the further below the surface. Deep foundations are weight of the building or structure. used when the soil near the surface is not strong enough to support the weight of the structure, or when there are factors such as high water tables, weak or loose surface soils, or heavy loads.  Types of Foundations 1. Shallow Foundation 2. Deep Foundations Spread footings Pile foundations Combined footings Piers Strip footings Caissons Conventional Slab-on-grade Mat or Raft foundation Post-tensioned Slab-on-grade Floating foundation Raised-wood flood Basement-type foundation Grillage footing Mat foundation Shallow Foundation Spread Footings These are square or rectangular concrete slabs placed under a column to spread its weight evenly to the ground. The concrete is reinforced with steel for strength, and the column sits in the center of the footing. They are used to support a single column and prevent it from sinking into the ground. Shallow Foundation Combined Footings These are reinforced concrete footings designed to support more than one column. They are usually shaped like rectangles or trapezoids and are used when columns are placed close together or when the space between columns doesn't allow for separate footings. The combined footing helps distribute the load from multiple columns to the ground evenly. Shallow Foundation Strip Footings These are long, reinforced concrete foundations used to support load-bearing walls. They have a uniform width and are not very deep. Strip footings spread the weight of the wall evenly onto the ground, providing stability to the structure. Shallow Foundation Conventional Slab-on-grade A flat concrete slab poured directly on the ground, reinforced with steel bars and wire mesh for strength. It includes footings under load-bearing walls to support the structure Shallow Foundation Post-tensioned Slab-on-grade A concrete slab foundation strengthened by tightening steel cables (tendons) inside the slab after it’s poured. This method increases durability and is commonly used in ribbed, California, and PTI foundations. Shallow Foundation Raised-wood floor This type of foundation uses footings around the edges to support wood beams and a wooden floor system. Additional support inside is provided by smaller pad or strip footings. A crawl space is created between the wooden floor and the ground, allowing access for utilities or ventilation. Shallow Foundation Grillage footing Grillage footing is a type of foundation that uses layers of steel beams or girders, encased in concrete, to distribute heavy loads over a larger area. To spread concentrated loads from structures like columns or chimneys over a wider area, ensuring stability on soils with low bearing capacity. Shallow Foundation Mat Foundations This is a large, thick concrete slab that spreads across the entire area under a building to support the entire structure. It is reinforced with steel for strength and usually has a uniform thickness. It is called a shallow foundation when it is built at or close to the ground level. It is often used for buildings with heavy loads or on soil that cannot support individual footings. Deep Foundation Driven Piles These are long, slender supports made of wood, steel, or precast concrete. They are hammered into the ground using special equipment to provide a strong foundation, especially in areas with weak or unstable soil. Other types of piles These include piles like bored piles (drilled and filled with concrete), cast-in-place piles (concrete poured directly at the site), and composite files (made of a combination of materials like concrete and steel). They are used based on the soil conditions and project requirements. Deep Foundation Piers These are large-diameter columns made of reinforced concrete, similar to cast-in-place piles. They are commonly used with grade beams to support foundations on soils that expand and shrink, providing stability for the structure. Deep Foundation Caissons Are large reinforced concrete piers, often usd in deep foundations. They can also refer to watertight underground structures used for construction below water or unstable ground. Deep Foundation Mat or Raft Foundation Floating Foundation A large concrete slab supporting the A foundation where the structure’s entire structure. If built below ground weight is balanced excavating soil or supported by piles or piers, it is and building a basement, reducing classified as a deep foundation. pressure on the ground. Deep Foundation Basement-type foundation A foundation commonly used in areas with freezing temperatures, consisting of perimeter footings and walls that support a wood floor system. The basement floor is typically made of concrete Foundation Failures Foundation failures occur when a foundation is unable to support the load of a structure effectively, leading to excessive settlement, tilting, cracking, or structural instability. This can result from inadequate design, poor construction, soil instability, or external factors like water damage or seismic activity. Causes of Foundation Failure SOIL RELATED ISSUES DESIGN AND CONSTRUCTION ERRORS Inadequate bearing capacity Incorrect foundation type selection Differential settlement Insufficient depth or size of foundation Expansive or shrinkable soils Substandard materials used in construction OTHER FACTORS ENVIRONMENTAL FACTORS Overloading beyond design Water table fluctuations capacity Erosion or scouring around the Adjacent excavation or foundation construction activity Earthquakes or other seismic activities Types of Foundation Failures STRUCTURAL FAILURE FUNCTIONAL FAILURE Cracking Inability to support the intended Tilting load without excessive settlement Signs of Foundation Failure Crack in walls, floors, or ceilings Doors and windows that stick or don’t close properly Uneven or sloping floors Water leakage or dampness in basements Preventive Measures Soil testing and proper site investigation Adequate design and construction practices Regular Maintenance and inspection of structures Soil Considerations SOIL TYPE Clay Sandy Soil Silt Gravel Loam SOIL BEARING CAPACITY Ability of soil to support loads without much settlement SOIL MOISTURE CONTENT High moisture weakens soil and may lead to settlement SOIL COMPACTION Compacted soil increases stability and reduces settlement risks Soil Considerations SOIL PERMEABILITY Determines how easily water passes through soil SOIL SHEAR STRENGTH Resistance to shear forces SOIL DENSITY Density soils generally provide better support and stability SUBSURFACE CONDITIONS Presence of rock layers, groundwaters, or voids ENVIRONMENTAL FACTORS Risk of soil erosion, landslides, earthquakes effects or nearby construction Soil Considerations Importance of Soil Mechanics It helps engineers how soil behaves under loads Soil properties such as strength, compressibility and permeability impact foundation stability Engineers study these properties to design safe foundations that can support structures without failure. Soil consists of various materials, including broken rock or volcanic ash, which behave differently under stress. Studying soil mechanic ensures foundations perform well, preventing issues like settling or collapse. Laboratory Testing Techniques for Soil Accuracy in Soil Testing depends on several factors: 1. Proper Sampling - Laboratory techniques are only as good as the samples provided. Proper sampling ensures that the test results represent the entire field or area being analyzed. 2. Appropriate Testing Methods - Using techniques suited to the specific soil type prevents misleading results. For example, testing methods that fail to consider soil pH or organic matter content may not accurately reflect nutrient availability. Laboratory Testing Techniques for Soil Accuracy in Soil Testing depends on several factors: 3. Quality Control - The guide emphasizes the importance of selecting labs with robust quality control measures. Accreditation by programs ensures that the lab adheres to standardized protocols, reducing variability in results. (Jones et al., 2024) Laboratory Testing Techniques for Soil 3 Common Field Tests for Soil: 1. Standard Penetration test (SPT) - A sampler is driven into the ground with a hammer, and the number of blows required to penetrate the soil is recorded as the SPT N value. This value indicates soil density, ranging from very loose to very dense. 2. Cone Penetration Test (CPT) - A cone-shaped probe is pushed into the ground to measure soil resistance continuously. It provides detailed data on soil strength in real-time but requires specialized equipment and is less common in the U.S. Laboratory Testing Techniques for Soil 3 Common Field Tests for Soil: 3. Vane Shear Test (VST) - A sampler is driven into the ground with a hammer, and the number of blows required to penetrate the soil is recorded as the SPT N value. This value indicates soil density, ranging from very loose to very dense. Laboratory Testing Techniques for Soil Effective Stress, Stress Distribution, and Settlement Analysis Effective Stress - It is the stress carried by the soil skeleton, calculated as total stress (σ) minus pore water pressure (ν): σ′=σ−ν. Stress Distribution - Stress distribution in soil describes how loads applied to the surface spread through soil layers, influenced by total stress and pore water pressure. Settlement Analysis - This examines how structures deform over time due to applied loads on soil. Settlement can be immediate (elastic) or consolidation (slow, over time). Engineers use methods like the 2:1 method and consider soil conditions to design stable foundations that account for expected settlement. Purpose of Field Exploration The purpose of the field exploration is to obtain the following (M. J. Tomlinson, ‘‘Foundation Design and Construction,’’ 5th ed., John Wiley & Sons, Inc., New York): 1. Knowledge of the general topography of the site as it affects foundation design and construction, and the available access for construction vehicles and materials. 2.The location of buried utilities such as electric power and telephone cables, water mains, and sewers. 3. The general geology of the area, with particular reference to the main geologic formations underlying the site and the possibility of subsidence from mineral extraction or other causes. Purpose of Field Exploration 4. The previous history and use of the site, including information on any defects or failures of existing or former buildings attributable to foundation conditions. 5. Any special features such as the possibility of earthquakes or climate factors such as flooding, seasonal swelling and shrinkage, permafrost, and soil erosion. 6. The availability and quality of local construction materials such as concrete aggregates, building and road stone, and water for construction purposes. 7. For maritime or river structures, information on tidal ranges and river levels, velocity of tidal and river currents, and other hydrographic and meteorological data. Purpose of Field Exploration 8. A detailed record of the soil and rock strata and groundwater conditions within the zones affected by foundation bearing pressures and construction operations, or of any deeper strata affecting the site conditions in any way. 9. Results of laboratory tests on soil and rock samples appropriate to the particular foundation design or construction problems. 10. Results of chemical analyses on soil or groundwater to determine possible deleterious effects of foundation structures. References Pile Buck. (2023, October 17). Shallow Versus Deep Foundations: Factors to Consider, Common Mistakes and Pitfalls, and More. Pile Buck Magazine. https://pilebuck.com/shallow-versus-deep-foundations-factors-consider-common-mistakes- pitfalls/ Adewale, A. M., & Favour, O. A. (2024, November 4). INVESTIGATING THE INFLUENCE OF SOIL PROPERTIES ON FOUNDATION SETTLEMENT AND BEARING CAPACITY. ResearchGate. https://doi.org/10.13140/RG.2.2.15303.30885 Coduto, D. P., Man-Chu Ronald Yeung, & Kitch, W. A. (2011). Geotechnical engineering : principles and practices. Pearson Prentice Hall. Das, B. M., & Nagaratnam Sivakugan. (2018, January 1). Principles of Foundation Engineering. ResearchGate. https://www.researchgate.net/publication/322975640_Principles_of_Foundation_Engineering Tomlinson, M., & Woodward, J. (2014). Pile Design and Construction Practice. In CRC Press eBooks. Informa. Pile Buck. (2023, October 17). Shallow Versus Deep Foundations: Factors to Consider, Common Mistakes and Pitfalls, and More. Pile Buck Magazine. https://pilebuck.com/shallow-versus-deep-foundations-factors-consider-common-mistakes-pitfalls/ References Fayaz Kaladi, Wang, F., & Kherazi, F. Z. (2023). Structural Stability: A Comprehensive Review of Pile Foundations in Construction. Journal of South Asian Development, 12(4), 412–425. https://www.researchgate.net/publication/376981407_Structural_Stability_A_Comprehensive_Review_of_Pile_Founda tions_in_Construction civilnotebook. (2023, June 25). Piles | Types of Pile | Concrete Piles | Timber Piles | Steel Piles | Composite Piles. Civilnotebook.com. https://www.civilnotebook.com/advantages-and-disadvantages-of-concrete-pile-composite-timber- steel-piles/ Muthukkumaran, K., Keerthi Raaj, S., & Vinoth Kumar, M. (2016). Assessment of pile failures due to excessive settlement during pile load test. Japanese Geotechnical Society Special Publication, 2(73), 2520–2524. Pile Buck. (2023, October 17). Shallow Versus Deep Foundations: Factors to Consider, Common Mistakes and Pitfalls, and More. Pile Buck Magazine. https://pilebuck.com/shallow-versus-deep-foundations-factors-consider-common-mistakes-pitfalls/ References Lunne, T., Peter, & Powell, J. (2002). Cone Penetration Testing in Geotechnical Practice. https://doi.org/10.1201/9781482295047 Jones, G. B., Moore, A., & Smith, E. (2024, May). Soil Testing Lab Selection and Recommended Analytical Methods for Oregon. OSU Extension Service. https://extension.oregonstate.edu/catalog/pub/em-9423-soil-testing-lab-selection- recommended-analytical-methods-oregon Thank you