Approved_Document A Flashcards
What is Requirement A1?
A1 ensures buildings can sustain loads without excessive movement or failure.
What types of loads must buildings be designed to resist?
Dead loads, imposed loads, wind loads, snow loads, and accidental loads.
What is a dead load?
The weight of the building’s permanent structure, including walls, floors, and fixed equipment.
What is an imposed load?
Loads caused by occupancy, furniture, and temporary equipment within a building.
Why must buildings account for wind loads?
Wind can exert significant horizontal and uplift forces on structures, requiring design considerations.
What are snow loads?
The weight of accumulated snow on roofs, which varies based on geographical location and roof design.
What is an accidental load?
A sudden impact or force, such as vehicle collisions, explosions, or equipment failure.
What is the purpose of structural robustness?
To prevent localised failures from leading to progressive collapse.
How should floors be designed to support loads?
They must be capable of carrying the imposed loads stated in BS EN 1991-1-1 (Eurocode 1).
How are roof structures designed to withstand loads?
By considering dead loads, imposed loads, wind uplift, and snow accumulation.
What is lateral stability in structural design?
The ability of a structure to resist horizontal forces such as wind or seismic activity.
Why is differential settlement a concern in structural loading?
It can cause cracking, tilting, and failure in structures if loads are unevenly distributed.
What factors influence load distribution in a structure?
Material strength, span length, connection types, and support conditions.
How are foundation loads determined?
Based on soil conditions, structural weight, and anticipated live loads.
What are the load-bearing capacity requirements for residential buildings?
Must comply with BS EN 1990 and BS EN 1991 standards for structural safety.
What is a load path in structural engineering?
The route through which forces travel from the point of application to the ground.
What is the minimum design safety factor for structural loads?
Typically 1.5 to 2.0, depending on material type and load combination.
How do load combinations affect structural design?
Structures must be designed to resist the worst-case combination of dead, live, wind, and accidental loads.
Why is redundancy important in load-bearing structures?
Redundancy ensures alternative load paths exist to prevent collapse if one element fails.
How do material properties affect load resistance?
Different materials (steel, concrete, timber) have unique strength and deformation characteristics.
What structural measures are taken to prevent excessive deflection under load?
Beams and floors must be designed with appropriate stiffness to limit deflection.
What is the significance of Eurocode 1 in structural loading?
It provides guidelines for assessing actions on structures, including imposed and environmental loads.
What are the fire load considerations in structural design?
Buildings must be designed to maintain structural integrity under fire conditions.
How does loading affect multi-storey buildings?
Higher floors must account for cumulative loads and lateral stability against wind and seismic forces.
What additional loading considerations apply to industrial buildings?
Heavy machinery, dynamic loads, and impact loads require stronger structural elements.
What is Requirement A2?
A2 ensures that buildings are designed to withstand ground movement without structural damage.
What are the main types of ground movement?
Subsidence, heave, landslides, settlement, and shrink-swell movement of clay soils.
What is subsidence?
The gradual sinking of a building due to unstable ground conditions.
What is heave?
The upward movement of the ground caused by the expansion of soil, often due to increased moisture.
What is differential settlement?
Uneven sinking of a structure’s foundation due to variations in soil load-bearing capacity.
How can ground movement affect buildings?
It can cause cracking, structural instability, and foundation failure.
What factors influence ground movement?
Soil type, water content, tree roots, seasonal changes, and nearby excavations.
What is shrink-swell movement in clay soils?
Swelling occurs when clay absorbs water, and shrinking occurs when it dries out, causing cyclic movement.
How can trees and vegetation impact ground stability?
Tree roots extract moisture, leading to shrinkage of clay soils, increasing subsidence risk.
What foundation types help resist ground movement?
Deep foundations such as pile foundations and raft foundations distribute loads more effectively.
What are the effects of mining activity on ground stability?
Old mine workings can lead to unexpected ground subsidence and structural damage.
How is ground movement risk assessed for new buildings?
Through geotechnical surveys and soil testing before construction.
What construction techniques mitigate the impact of ground movement?
Flexible foundations, reinforced structures, and movement joints help accommodate minor shifts.
What are the regulations regarding ground stability in high-risk areas?
Buildings must comply with BS 8004 and geotechnical assessments must be conducted.
How does groundwater affect building stability?
Changes in groundwater levels can cause soil erosion, heave, or settlement.
What role do retaining walls play in preventing landslides?
They provide lateral support to slopes and help prevent soil movement.
What is an underpinning foundation?
A method used to strengthen an existing foundation by extending it deeper into stable ground.
Why are movement joints used in buildings?
To allow for minor expansion and contraction due to temperature or ground shifts.
What are signs of structural distress due to ground movement?
Cracks in walls, uneven floors, misaligned doors/windows, and leaning walls.
How do building regulations address flood-prone areas?
Buildings must be designed with elevated foundations and proper drainage to mitigate flood risk.
What are ground anchors and how do they work?
Tensioned steel rods drilled into stable ground to provide additional structural support.
What are the key considerations for basements in unstable ground?
Proper waterproofing, reinforcement, and drainage must be designed to prevent ground movement damage.
How do soil conditions affect foundation design?
Soft soils require deeper or reinforced foundations, while stable soils allow shallower designs.
What precautions should be taken for buildings near slopes?
Slope stability analysis, retaining walls, and proper drainage must be incorporated.
What additional ground movement risks apply to large commercial buildings?
Greater weight distribution requires extensive soil testing, reinforced foundations, and seismic design considerations.
What is Requirement A3?
A3 ensures that buildings are designed to prevent disproportionate collapse in the event of structural failure.
What is disproportionate collapse?
The failure of a small part of a structure leading to the failure of the entire building or a significant portion of it.
What are common causes of disproportionate collapse?
Explosions, accidental impacts, structural overloading, and material degradation.
What types of buildings are most at risk of disproportionate collapse?
High-rise buildings, large-span structures, and buildings with load-bearing walls.
What regulations apply to the design of buildings to prevent disproportionate collapse?
BS EN 1991-1-7 (Eurocode 1) and Approved Document A guidelines.
What are key design strategies to prevent disproportionate collapse?
Robust structural systems, redundancy, and alternative load paths.
What is structural redundancy?
The presence of additional load paths that allow a structure to remain stable if a primary element fails.
How do load-bearing walls contribute to structural stability?
They distribute vertical and lateral loads to prevent progressive collapse.
What is the role of tie forces in structural stability?
Tie forces connect structural elements together, improving resistance to collapse.
What are horizontal and vertical ties in building design?
Horizontal ties connect floors and walls; vertical ties secure floors to foundations.
What is an alternative load path?
A secondary means of distributing loads if a primary structural element fails.
What is a key element in structural integrity?
Any structural component whose failure could trigger disproportionate collapse.
How can buildings be designed to mitigate explosion risks?
Using blast-resistant materials and structural compartmentation.
What is the significance of compartmentation in preventing progressive collapse?
It isolates failures to small areas, preventing them from spreading.
How do steel-framed buildings resist disproportionate collapse?
They use continuous frames and bolted connections to maintain stability.
What additional design measures are required for buildings over five storeys?
Enhanced robustness, additional load paths, and higher material specifications.
What role does material selection play in collapse prevention?
High-strength and ductile materials reduce the likelihood of sudden failure.
How do impact-resistant structures prevent collapse?
They use reinforced walls, energy-absorbing materials, and strategic load redistribution.
What measures should be taken for buildings in seismic zones?
Flexible joints, base isolators, and reinforced core structures should be included.
Why is fire resistance important in preventing disproportionate collapse?
Structural elements must withstand fire conditions to maintain load-bearing capacity.
What is a robustness check in structural design?
An assessment ensuring that a building remains stable under extreme conditions.
What is the importance of tying elements together in modular buildings?
Strong interconnections between prefabricated elements prevent collapse.
What role do vertical bracing systems play in stability?
They provide lateral support against wind and seismic forces.
What regulations apply to buildings with large open-plan areas?
Stronger beams, additional supports, and alternative load paths must be incorporated.
What special considerations apply to bridges and large-span structures?
Multiple support points and redundancy must be designed to avoid total failure in case of localised damage.
