Types of loads in building

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Table of Contents

Various types of loads must be considered in building design and construction to ensure safety, functionality, and structural stability.

Types of loads

  1. Dead Load
  2. Live load
  3. Wind Load
  4. Earthquake Load (Seismic load)
  5. Snow Load
  6. Rain Load
  7. Thermal Load
  8. Impact Load
  9. Settlement Load
  10. Construction Load
  11. Blast Load
  12. Lateral Earth Pressure Load
  13. Dynamic Load

Dead Load (DL)

Definition

Dead Load

Dead load refers to the permanent, static loads constantly applied to a structure. These are the weights of the building’s components and other elements fixed in place and do not change over time.

Characteristics of Dead Load

  1. Constant Magnitude: The magnitude of the dead load remains constant throughout the structure’s life.
  2. Predictable: Dead loads are easily estimated since they depend on the weight of the building’s materials, which are known and unchanging.
  3. Long-Lasting: Unlike live loads, these loads do not vary and are not subject to changes in usage or environment.
  4. Acts Vertically Downward: The force of dead loads acts downward due to gravity, typically on the structure’s beams, columns, floors, and foundations.

Examples of Dead Loads

  1. Structural Components:
    • Floor Slabs: Weight of concrete or other materials used for flooring.
    • Roofing Systems: Weight of roof materials, including trusses, beams, and coverings.
    • Beams and Columns: The weight of load-bearing elements such as beams, girders, and columns.
    • Walls: The weight of the exterior and interior walls (masonry, concrete, or steel).
  2. Finish Materials:
    • Floor Finishes: Tile, marble, or carpet laid on the floor.
    • Ceiling and Wall Finishes: Plaster, paint, drywall, and cladding.
  3. Permanent Fixtures:
    • Fixed Equipment: Air conditioning systems, heating units, or built-in cabinets.
    • Partitions: Non-movable or permanent partition walls.

Importance of Dead Load in Structural Design

  • Structural Stability: Dead loads contribute to the overall stability and strength of a building, ensuring that the structure can withstand its weight.
  • Foundation Design: Dead loads are crucial for the design of foundations and substructures, as they influence the soil-bearing capacity and foundation depth.
  • Load Distribution: Engineers use dead load calculations to distribute the load appropriately across beams, columns, and other structural elements.

Calculation of Dead Load

Dead load is typically calculated based on the material weights and dimensions of the structure. For example:

  • Concrete has a typical density of 2400 kg/m³.
  • Steel has a density of 7850 kg/m³.
  • Wood density varies depending on type, ranging from 400 to 900 kg/m³.

density or unit weight for civil construction materials

To calculate the dead load of a concrete slab, for example, the formula would be:

Dead Load = Area of Slab × Density of Material × Thickness of Slab

Dead Load vs. Live Load

  • Dead Load is permanent and constant, while Live Load is variable, depending on occupancy, equipment, and other temporary factors.
  • Dead load is typically accounted for in the initial stages of design and construction, whereas live loads are more important when designing for operational conditions.

Example of Dead Load Calculation

Let’s say we have a concrete floor slab with:

  • Area = 50 m²
  • Thickness = 0.2 meters (20 cm)
  • Concrete density = 2400 kg/m³

The dead load of this slab would be:

Dead Load=50 m2×0.2 m×2400 kg/m3 =24,000 kg =24 tonnes

This load would then determine how much weight the supporting beams, columns, and foundations must handle. Dead loads are fundamental to structural design, as they provide a baseline for the loads that the building must support consistently.

Code books used for Dead Load

Live Load (LL)

Definition

Live load

Live load refers to the temporary or moving loads that act on a structure during its use. These loads vary in magnitude, location, and distribution over time. Unlike dead loads, which are permanent, live loads fluctuate depending on the building’s occupancy and usage.

Characteristics of Live Load

  1. Variable: Live loads change depending on the function or activity taking place within the building.
  2. Temporary: These loads are not permanent and are only present when people, furniture, equipment, or vehicles are inside or on the structure.
  3. Dynamic: Live loads can vary in intensity and location, meaning they may shift or change as people or objects move.
  4. Influenced by Building Usage: The magnitude of live load depends on how the building is used. For example, a commercial office building will have different live load requirements compared to a residential building or a parking garage.

Examples of Live Loads

  1. People:
    • Occupants in residential, commercial, or industrial spaces (e.g., people moving in an office, walking in a hallway).
  2. Furniture and Equipment:
    • Tables, chairs, desks, and office equipment in office buildings.
    • Appliances, beds, and other furniture in residential buildings.
  3. Vehicles:
    • Cars, trucks, and other vehicles in parking garages or loading areas.
  4. Temporary Loads:
    • Materials, tools, and equipment in construction zones.
    • Goods are stored in warehouses or retail spaces.
  5. Snow and Rain:
    • While snow load can be considered a dead load when accumulated on a building, any additional snow (or rain) accumulation over a certain capacity may be regarded as a live load, particularly if it’s unpredictable.

Importance of Live Load in Structural Design

  • Design for Flexibility: Live loads help engineers design structures that are capable of handling varying loads depending on occupancy.
  • Building Safety: Accurately estimating live loads ensures that the structure can support the movement of people, equipment, and vehicles without risk of collapse or excessive deflection.
  • Code Compliance: Building codes (e.g., International Building Code, ASCE) specify minimum live load requirements for different types of buildings based on their use, ensuring uniform safety standards.

Factors Affecting Live Load

  1. Type of Building: The live load is determined by how the building is used (e.g., residential, commercial, industrial).
  2. The density of Occupants: Buildings with higher occupancy levels (e.g., theatres, stadiums) will have higher live load requirements.
  3. Mobility and Movement: For example, a hospital or an office may have varying live loads based on how people move and where furniture is located.
  4. Location: For example, a warehouse may have a higher live load due to stored goods or machinery, while a residential building may have a lower live load.

Live Load Calculation

Live load calculations are often based on standard values provided by building codes or structural design guidelines. For instance:

  • Residential Buildings: Live load is typically 1.5 kN/m² (kilo-newtons per square meter) or 40 psf (pounds per square foot).
  • Office Buildings: Live load is usually around 2.0 – 2.5 kN/m² or 50 – 60 psf.
  • Public Areas (Stadiums, Theaters): Higher live loads can be assumed, such as 4.0 kN/m² or 100 psf for heavily occupied spaces.

For a specific floor with a uniform live load requirement:

Live Load = Area × Live Load Intensity

For example, if a residential floor has an area of 100 m², with a live load of 2 kN/m²:

Live Load=100 m2×2 kN/m2=200 kN

This would mean the structure needs to be designed to support an additional 200 kN of load from people and furniture.

Live Load vs. Dead Load

  • Dead Load is the permanent weight of the building and its materials (e.g., walls, floors, and roof), while Live Load is temporary and variable (e.g., people, furniture, vehicles).
  • Dead load is more predictable, while live load fluctuates depending on usage.

Example of Live Load Calculation

Let’s say you are designing an office building and the live load requirement for the floor is 4 kN/m². If the area of the office floor is 500 m², the total live load on that floor would be:

Live Load=500 m2×4 kN/m2=2000 kN

This means the beams, columns, and foundations must be designed to support an additional 2000 kN of load from occupants, furniture, and other movable elements.

Live load is crucial for ensuring that buildings can handle fluctuating forces without compromising safety or structural integrity. By properly accounting for this variable load, engineers ensure the building performs well under different conditions and usage scenarios.

Code books used for Live Load

Wind Load (WL)

Definition

Wind load

Wind load refers to the force exerted by the wind on a structure. It is a dynamic load that can create pressure on the surfaces of buildings, leading to structural stresses. Wind loads vary based on wind speed, direction, and the characteristics of the building, such as its height, shape, and location.

Examples

  • Pressure on walls and windows.
  • Uplift forces on roofs.

Factors Affecting Wind Load

  • Wind speed and direction.
  • Building height, shape, and location.
  • Importance: Crucial for tall buildings and structures in wind-prone areas.

Wind Load Calculation

Wind load is typically calculated using formulas that take into account the basic wind speed, building height, and structural characteristics. In most building codes, the following steps are used to estimate wind load:

  1. Determine the Basic Wind Speed (V):
    • The basic wind speed is defined by geographic location and is often given in meters per second (m/s) or miles per hour (mph).
  2. Calculate the Wind Pressure (P): The wind pressure can be calculated using the formula: P=0.5×Cd×ρ×V2
  3. Where:
    • P = Wind pressure (in Pascals, Pa)
    • Cd= Drag coefficient, which depends on the shape of the building and surface roughness
    • ρ = Air density (typically 1.225 kg/m³ at sea level)
    • V = Wind velocity (in meters per second, m/s)
  4. Determine the Wind Load (F): The wind load on a surface is calculated by multiplying the wind pressure by the area exposed to the wind: F=P×A
  5. Where:
    • F = Wind load (in Newtons, N)
    • A = Area exposed to the wind (in square meters, m²)
  6. Adjustment Factors:
    • Exposure Factor (K_e): This factor adjusts for the wind environment around the building (e.g., urban vs. open terrain).
    • Building Height Factor (K_h): Wind pressure increases with height, so this factor adjusts the calculation for taller buildings.
    • Shape Factor (K_s): Adjusts for the shape of the building, influencing how wind interacts with it.

Code books used for Wind Load

Earthquake Load (Seismic Load)

Definition

seismic load

Earthquake load, also known as seismic load, refers to the forces exerted on a structure due to ground motion during an earthquake. These forces are dynamic and can cause structures to sway, shake, or even collapse if not properly accounted for in the design. Seismic loads are influenced by the magnitude of the earthquake, the distance from the epicentre, and the type of soil the building sits on.

Characteristics

  • Acts in all directions but predominantly horizontally.
  • Depends on the building’s mass, stiffness, and location in seismic zones.
  • Importance: Necessary for earthquake-resistant design, especially in seismic-prone areas.

Earthquake load calculation

Seismic loads are typically calculated using formulas provided by building codes, such as the International Building Code (IBC) or ASCE 7, which are based on the expected ground motion in the area, the building’s importance, and its structural characteristics.

V=Cs​×W

Code books used for Earthquake Load

Snow Load

Definition

Snow load

Snow load refers to the weight of snow and ice accumulated on a building’s roof or other horizontal surfaces. It is a type of live load, as the amount of snow can vary based on weather conditions, geography, and seasonal factors. Snow load is especially important in regions that experience heavy winter snowfall, and it can significantly impact the structural design of buildings, particularly roofs.

Factors Affecting Snow Load

  • Snowfall intensity and roof slope.
  • Duration of snow retention.
  • Examples:
    • Weight of accumulated snow/ice.
  • Importance: Relevant in cold climates.

Snow Load Calculation

Snow loads are calculated using standards provided in building codes, such as the International Building Code (IBC) or ASCE 7, which provide formulas based on the local snow conditions, roof type, and building characteristics.

Basic Snow Load (Ps)

The basic snow load is typically calculated using the following formula: Ps=Ce×Ct×Is×Ss

Where:

  • Ps​ = Snow load (in pounds per square foot, psf, or kilonewtons per square meter, kN/m²)
  • Ce = Exposure factor (adjusts for wind exposure)
  • Ct​ = Thermal factor (adjusts for temperature variations affecting snow accumulation)
  • Is​ = Importance factor (adjusts for the building’s occupancy and importance)
  • Ss​ = Ground snow load (the maximum snow load for a specific location, typically provided by building codes)

This formula provides the design snow load based on the maximum snow that can accumulate on a flat roof.

Considerations for Roof Slope

The snow load increases as the roof slope decreases. The slope can be accounted for with a snow load reduction factor. For instance:

  • Flat roofs (0°): Higher snow accumulation, no shedding.
  • Sloped roofs: Snow load is reduced as the slope increases, as snow slides off more easily.

The snow load on a sloped roof is given by: Ps=Ce×Ct×Is×Ss×Fs

Where Fs​ is the snow load reduction factor for the roof slope.

For typical slopes:

  • Slope between 0° to 10°: Significant accumulation
  • Slope between 10° to 30°: Moderate accumulation
  • Slope above 30°: Lower accumulation, may require additional factors like drifting or redistribution.

Example of Snow Load Calculation

Let’s say we have the following data:

  • Ground snow load (Ss​) = 30 psf (based on the location)
  • Exposure factor (Ce​) = 1.0 (assuming average wind exposure)
  • Thermal factor (Ct​) = 1.0 (for typical temperature conditions)
  • Importance factor (Is​) = 1.0 (for a normal building)

For a flat roof (0° slope), the snow load would be: Ps=1.0×1.0×1.0×30=30 psf

This means the building must be designed to support 30 psf of snow load on the roof.

If the roof has a slope of 30°, and the snow load reduction factor (Fs) is 0.7, the snow load would be: Ps=1.0×1.0×1.0×30×0.7=21 psf

This means the snow load would be reduced to 21 psf for the sloped roof.

Code books used for Snow Load

Rain Load

Definition

Rain Load

Rain load is the weight accumulated water exerts due to rainfall on a building’s roof or other horizontal surfaces. While not typically as large as snow loads, rain loads are important for structural design, especially for roofs with poor drainage or areas prone to heavy rainfall or storms. Rainwater can accumulate on roofs, causing a potential increase in loading if not properly managed through drainage systems.

  • Examples:
    • Water ponding on roofs.
    • Weight of retained water.
  • Importance: Considered in areas with heavy rainfall.

Rain Load Calculation

Rain load is generally calculated using local weather data, building code requirements, and specific roof characteristics. The primary concern is the water accumulation on the roof surface, which depends on the rainfall intensity and roof design.

Basic Rain Load Formula

The basic formula for calculating rain load on a roof is: Lr=ρ×A×H

Where:

  • Lr​ = Rain load (in kN or lb)
  • ρ = Density of water (typically 9.81 kN/m³ or 62.4 lb/ft³)
  • A = Area of the roof or surface exposed to rainwater (in square meters or square feet)
  • H = Height of water accumulation (in meters or feet) due to rainfall (this is typically determined based on the maximum expected depth of water for the given area)

Rainfall Intensity

Rainfall intensity is typically expressed in inches per hour (in/hr) or millimetres per hour (mm/hr). It is used to estimate how much water will accumulate on the roof surface over a certain period.

In many areas, building codes provide specific values for the expected rainfall intensity based on the location, along with the maximum rainwater accumulation depth for different types of roofs.

Example of Rain Load Calculation

Let’s assume the following:

  • Roof area (A) = 100 m²
  • Height of water accumulation (H) = 0.05 m (5 cm)
  • Water density (ρ) = 9.81 kN/m³

The rain load on the roof would be: Lr=9.81 kN/m3 × 100 m2 × 0.05 m = 49.05 kN

So, the rain load on this roof would be approximately 49.05 kN.

Code books used for Rain Load

Thermal Load

Definition

thermal stress

Thermal load refers to the stresses and forces imposed on a building’s structure due to temperature changes. These changes can cause expansion and contraction of materials, resulting in deformations that need to be accounted for in the design. Thermal loads are important in structures exposed to varying temperatures, such as in areas with extreme seasonal temperature fluctuations or buildings that experience significant internal heat sources.

  • Examples:
    • Expansion or contraction of materials due to heat.
    • Cracking in concrete or steel elements.
  • Characteristics: Significant in structures exposed to extreme temperature variations.

Thermal Load Calculation

Thermal loads are typically calculated based on the temperature change and the thermal properties of the materials used in construction. The key parameters involved in calculating thermal load are:

  1. Temperature Change (ΔT):
    • The difference between the temperature at which the material is installed and the temperature it will be subjected to during its operation (e.g., day vs. night, seasonal changes, or HVAC settings).
  2. Coefficient of Thermal Expansion (α):
    • The coefficient of thermal expansion defines the change in length per unit length per degree of temperature change for a material. It is typically given in mm/(m·°C) or in/(in·°F).
  3. Length or Volume of the Material:
    • The length (for linear thermal expansion) or the volume (for volumetric thermal expansion) of the material is also a key factor. For instance, the length of a steel beam or the area of a concrete slab.
  4. Thermal Strain (ϵ):
    • Thermal strain can be expressed as: ϵ=α×ΔT Where ϵ is the strain (deformation) due to thermal expansion, α is the coefficient of thermal expansion, and ΔT is the temperature change.

Example of Thermal Load Calculation

Let’s calculate the thermal expansion for a steel beam subjected to a temperature change:

  • Coefficient of Thermal Expansion for Steel (α): 12 × 10⁻⁶ /°C
  • Length of the Steel Beam (L): 10 meters
  • Temperature Change (ΔT): 50°C

The change in length (ΔL) of the beam can be calculated using the formula: ΔL=L×α×ΔT.

ΔL=10 m×12×10−6/°C×50°C = 0.006 m = 6 mm

Thus, the steel beam would expand by 6 mm due to a 50°C temperature increase.

Code books used for Thermal load

Impact Load

Definition

Impact load refers to the load or force exerted on a structure when a moving object suddenly strikes it or when an object suddenly changes its velocity upon impact. Unlike static loads, which are constant and applied gradually, impact loads are dynamic and occur in a very short duration. These loads are often much higher than normal operational loads and can cause sudden deformations, vibrations, or even failure of structural components if not properly accounted for in the design.

  • Examples:
    • Vehicles striking barriers.
    • Equipment dropped on floors.
  • Importance: Considered for industrial structures or areas prone to collisions.

Impact Load Calculation

The impact load can be estimated using principles from dynamics, considering factors like the object’s velocity, mass, and the duration of the impact. A simplified approach to estimating impact force is based on the conservation of momentum.

Basic Formula

Impact load can be calculated using the following formula: Fimpact = m x v / Δt

Where:

  • Fimpact = Impact force (in Newtons, N)
  • m = Mass of the impacting object (in kilograms, kg)
  • v = Velocity of the object at the moment of impact (in meters per second, m/s)
  • Δt = Duration of the impact (in seconds, s)

The impact force is inversely proportional to the duration of the impact. If the impact occurs very quickly (i.e., a very short Δt), the impact force will be large.

Example of Impact Load Calculation

Let’s calculate the impact force for a falling object:

  • Mass of object m=100 kg
  • Velocity at impact v=10 m/s
  • Duration of impact Δt=0.1 s

Using the formula: Fimpact= (100 kg×10 m/s) / 0.1 s = 10,000 N

Thus, the impact force exerted by the object would be 10,000 N.

Code books used for Impact load

India:

United States:

Europe:

  • Covered in specialized sections of Eurocode 1 and Eurocode 2.

Settlement Load

Definition

DALL·E 2024 09 30 12.01.35 A 3D ultra HD rendered image of a building experiencing differential settlement. One side of the building appears to be sinking faster than the other

Settlement load refers to the forces and stresses that are applied to a building or structure due to the settling or subsidence of the ground beneath it. Settlement occurs when the soil or foundation material beneath a building shifts or compacts under the weight of the structure, leading to vertical displacement or sinking. This load is important to consider during the design phase, as it can cause uneven settlement or deformation of the structure, potentially leading to damage like cracks, misaligned walls, or even structural failure.

  • Examples:
    • Differential settlement of soil layers.
  • Impact: Can cause cracking or tilting in structures.

Settlement Load Calculation

The settlement load is typically considered when calculating bearing capacity and designing foundations. The following factors are taken into account:

  1. Soil Bearing Capacity:
    • The maximum load per unit area that the soil can support without undergoing excessive settlement. This value is critical for understanding the potential for settlement under the given building load.
  2. Building Load:
    • The total load from the building and its contents (including live load, dead load, and any additional loads like snow or wind). This weight is transferred to the foundation, and the underlying soil must support it without excessive settling.
  3. Settlement Formula:
    • A simplified formula for estimating settlement due to compression of soil layers is: S=qxB/E
  4. Where:
    • S = Settlement (in meters or millimetres), q = Applied load (in kN/m² or psf), B = Width of the foundation (in meters or feet), E = Modulus of elasticity of the soil (in kN/m² or psi)
    The formula takes into account the applied load and the soil’s ability to resist compression, giving an estimate of the amount of settlement that will occur.

Code books used for Settlement load

India

  • IS 6403: Bearing Capacity of Shallow Foundations.
  • IS 1904: General Requirements for Foundation Design.
  • IS 8009: Settlement Calculation for Shallow and Pile Foundations.

United States

  • ASCE 7: General Design Loads, including settlement.
  • ACI 318: Concrete Structures and Settlement Effects.

Europe

International

  • ISO 23469: Settlement Due to Seismic Effects.

Construction Load

Definition

Construction load refers to the temporary loads imposed on a structure during the construction phase. These loads are typically applied as part of the building process and can include the weight of construction materials, equipment, workers, and temporary structures. Construction loads are generally temporary and vary in magnitude and duration, depending on the stage of construction and the type of work being done.

Construction loads are important to consider when designing buildings because they can significantly affect the structural integrity during construction. A structure must be designed to withstand these loads until it is fully completed and capable of carrying its permanent loads (such as dead loads, live loads, and other loads).

  • Examples:
    • Weight of materials stored on-site.
    • Loads from scaffolding or formwork.
  • Importance: This must be considered during the construction phase to avoid accidents.

Calculation of Construction Loads

  1. Dead Load Calculation:
    • The temporary dead load includes materials, scaffolding, formwork, and any temporary structural elements. The load can be estimated by summing the weight of each component, taking into account the material density and the amount of material used.
  2. Live Load Calculation:
    • The live load during construction can vary widely depending on the number of workers, the type of work being done, and the equipment being used. It can be calculated based on the number of workers per floor, their equipment, and the type of work being performed at any given time.
    For example, if there are 10 workers on a floor and each worker is assumed to exert 0.5 kN of load, the total live load would be: Live Load=10×0.5 kN=5 kN.
  3. Equipment Load Calculation:
    • The equipment load is typically calculated based on the capacity of the machinery being used. Cranes, hoists, or lifts will have specified maximum load limits that should be considered when estimating the load applied to the structure.
  4. Material Load Calculation:
    • Material loads are calculated based on the volume of materials stored or used in the construction process. For example, the weight of concrete can be calculated by considering the volume of concrete and its density.
    For example, if you have 100 cubic meters of concrete (density = 2.4 kN/m³): Material Load=100 m3×2.4 kN/m3=240 kN

Code books used for Construction load

India:

United States:

Explosion or Blast Load

Definition

Explosion or blast load refers to the forces exerted on a structure due to an explosive event, such as a bomb detonation, chemical explosion, or gas explosion. The blast load is a type of dynamic load that occurs over a very short duration and typically involves very high pressure, causing significant damage to the structure. The impact of an explosion on a building or structure can result in structural deformation, failure of components, and catastrophic collapse in severe cases.

The effects of explosion or blast loads depend on various factors, including the size of the explosion, the distance from the blast, the type of material involved, and the nature of the structure being impacted. Designing for blast loads is particularly critical in facilities like military installations, petrochemical plants, airports, high-security buildings, and infrastructure in high-risk areas.

  • Examples:
    • Pressure waves impact walls and windows.
  • Importance: Considered for sensitive or high-security buildings.0

Code books used for Blast load

International Standards:

  • UFC 3-340-02: Unified Facilities Criteria – Structures to Resist the Effects of Accidental Explosions (used in the U.S.).
  • ISO 16933: Glass in Building – Explosion-Resistant Security Glazing – Test and Classification.

Lateral Earth Pressure Load

Definition

Insta post

Lateral earth pressure refers to the pressure exerted by soil or earth on a structure due to its weight and the forces it experiences from surrounding conditions. This pressure typically acts horizontally (laterally) on structures like retaining walls, basement walls, foundations, or tunnels, and can either push against or resist the structure, depending on the conditions and direction of the applied forces.

Lateral earth pressure is an important factor to consider in the design of walls, foundations, and other subterranean structures. It is caused by the weight of the soil or earth and can vary based on soil type, moisture content, depth, and other environmental factors.

  • Examples:
    • Pressure from soil or water behind retaining walls.
  • Importance: Crucial for retaining structures and basements.

Calculation of Lateral Earth Pressure

Rankine’s Earth Pressure Theory (Simplified Approach)

The Rankine theory provides a simple method for calculating active and passive earth pressures under idealized conditions (without cohesion and for simple wall configurations). The active and passive earth pressure can be calculated using the following formulas:

Active Earth Pressure (Pa) : Pa=Ka x Γ x H2

Where:

Ka = Active earth pressure coefficient

Γ = Unit weight of soil

H = Height of the wall

Passive Earth Pressure (Pp): Pp=Kp⋅Γ⋅H2

Where:

Kp = Passive earth pressure coefficient

The coefficients Ka and Kp​ depend on the angle of internal friction (φ) of the soil and the wall’s angle of inclination.

Coulomb’s Earth Pressure Theory (More Detailed)

Coulomb’s theory is a more complex approach that accounts for the wall friction and sloped backfill. It incorporates both active and passive pressures and takes into account the effects of wall friction and the angle of inclination of the backfill. The equations in Coulomb’s theory involve factors like: Wall friction angle, Backfill angle of repose, and Soil cohesion.

Terzaghi-Wegman and Other Methods:

Terzaghi-Wegman and other advanced methods take into account various real-world conditions, including wall flexibility, backfill material properties, and water pressures. These methods are used for more accurate calculations in complex scenarios.

Code books used for Lateral Earth Pressure load

India

  • IS 456 – 2000: Guidelines for lateral loads on concrete structures.
  • IS 3370: Provisions for earth pressure on storage structures.
  • IS 3764: 1992: Safety in excavation work involving lateral earth pressure.

United States

  • ASCE 7: General provisions for lateral earth pressure.
  • ACI 318: Lateral pressure effects on concrete walls.

Europe

Dynamic Load

Definition

A dynamic load refers to a type of load that changes over time, typically with rapid variations in magnitude and direction. Unlike static loads (which remain constant or change slowly), dynamic loads involve forces that fluctuate and are applied over a short period. These loads are characterized by their time-varying nature, often associated with vibrations, impacts, and other transient forces.

Dynamic loads can cause structures to experience vibration, oscillation, or deformation that differs significantly from the effects of static loads. They are particularly important in the design of structures such as bridges, high-rise buildings, and machinery, which are exposed to repetitive forces or impacts.

  • Examples:
    • Vibrations from machinery.
    • Traffic loads on bridges.
  • Importance: Requires analysis for structures subjected to frequent dynamic forces.

Design Considerations for Dynamic Loads

  1. Dynamic Analysis:
    • Engineers use dynamic analysis methods to study the effects of dynamic loads on a structure. This includes time-history analysis, modal analysis, and response spectrum analysis to understand how the structure will behave under varying loads.
  2. Resilience and Damping:
    • Structural components are designed to absorb and dissipate energy to reduce the impact of dynamic loads. This can be achieved through damping systems (e.g., shock absorbers, tuned mass dampers) that help control vibrations and reduce oscillations.
  3. Safety Factors:
    • Due to the unpredictability and potential severity of dynamic loads, safety factors are often incorporated into the design. These factors provide additional strength or flexibility to account for unforeseen conditions.
  4. Resonance Avoidance:
    • Structures are designed to avoid resonance by either changing the natural frequency of the structure or incorporating damping to mitigate vibrations. This is particularly important for tall buildings, bridges, and other large structures.
  5. Material Selection:
    • Materials that can withstand dynamic forces without failing due to fatigue, excessive deformation, or brittle fracture are carefully chosen. For instance, steel and reinforced concrete are often used in structures exposed to dynamic loads because of their high strength and durability.

Code books used for Dynamic Loads

India:

United States:

Europe:

  • Eurocode 1 and 8: Comprehensive treatment of dynamic loads including vibrations and seismic forces.

By analysing these loads, engineers ensure that buildings are safe, durable, and capable of withstanding various conditions over their lifespan.

Code books used for building loads

Dead Load

Live Load

Wind Load

Earthquake Load

Snow Load

Rain Load

Thermal load

Impact load

  • India:
  • United States:
  • Europe:
    • Covered in specialized sections of Eurocode 1 and Eurocode 2.

Settlement load

  • India
    • IS 6403: Bearing Capacity of Shallow Foundations.
    • IS 1904: General Requirements for Foundation Design.
    • IS 8009: Settlement Calculation for Shallow and Pile Foundations.
  • United States
    • ASCE 7: General Design Loads, including settlement.
    • ACI 318: Concrete Structures and Settlement Effects.
  • Europe
  • International
    • ISO 23469: Settlement Due to Seismic Effects.

Construction load

Blast load

  • International Standards
    • UFC 3-340-02: Unified Facilities Criteria – Structures to Resist the Effects of Accidental Explosions (used in the U.S.).
    • ISO 16933: Glass in Building – Explosion-Resistant Security Glazing – Test and Classification.

Lateral Earth Pressure load

  • India
    • IS 456 – 2000: Guidelines for lateral loads on concrete structures.
    • IS 3370: Provisions for earth pressure on storage structures.
    • IS 3764: 1992: Safety in excavation work involving lateral earth pressure.
  • United States
    • ASCE 7: General provisions for lateral earth pressure.
    • ACI 318: Lateral pressure effects on concrete walls.
  • Europe

Dynamic Loads

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