Structures Flashcards
What are cables considered in structural design?
Cables are considered highly efficient structural components capable of holding great amounts of tensile force with a relatively small cross-sectional area.
What forces can cables resist?
Cables can only resist axial tensile forces and not any compression or bending moment.
What shape does a cable form under a simple point load?
A cable under a simple point load forms two straight lines meeting at the point of application of the load.
What shape do cables sag into under a uniformly distributed load?
Cables sag into a catenary shape or a parabola under a uniformly distributed load.
Define a catenary in structural design.
A catenary is a funicular shape for an unloaded cable, determined solely by the self-weight of the cable, which is uniformly distributed along its length.
How does a catenary cable transfer load?
A catenary cable sags under a uniformly distributed load and transfers the load to its two supports in equal shares.
Under what condition does a suspension cable form a parabola?
A suspension cable forms a parabola when loaded uniformly across its span, with the self-weight being insignificant compared to the load.
What is the optimum sag-to-span ratio for a uniformly loaded parabolic cable?
The optimum sag-to-span ratio for a uniformly loaded parabolic cable is 33%.
What is the typical sag-to-span ratio for most suspended roof structures?
Most suspended roof structures have a sag-to-span ratio of 1:8 to 1:10.
List the three main categories of cable structures.
- Single-curvature structures
- Double-cable structures
- Double-curvature structures
What is an example of a single-curvature cable structure?
Dulles Airport Terminal is an example of a single-curvature cable structure.
What distinguishes double-cable structures from single-curvature structures?
Double-cable structures have additional stabilizing cables below the primary suspension cables to resist wind uplift.
What materials are commonly used for cables?
- Mild steel
- High strength steel
- Stainless steel
- Polypropylene
- Fiberglass
- Carbon
What is the breaking stress of high-strength steel cables?
The breaking stresses of high-strength steel cables exceed 200,000 psi.
What are the principal elements of a cable-supported structure?
- Main cables
- Vertical supports or towers
- Anchorages
- Stabilizers
What is the function of vertical supports in cable-supported structures?
Vertical supports keep the cables above the ground and provide essential reactions.
True or False: The main cables of a suspension bridge are placed vertically.
False.
What are the two types of anchorage systems for suspension bridges?
- Earth-anchored suspension bridge
- Self-anchored suspension bridge
What is a funicular arch?
A funicular arch is the inverted compressive equivalent of a suspension cable.
What does a catenary arch redirect forces into?
A catenary arch redirects forces into axial compression.
What happens to the shape of an arch when the loading changes?
The shape of the arch will no longer be funicular if the loading changes.
What is the economic span for using a cable-stayed structure?
The economic span for using a cable-stayed structure is between 50 and 500 ft.
Fill in the blank: The suitable sag to span ratio for a cable-stayed structure is around _______.
1:10
What is the typical cable diameter range based on loads and span?
The cable diameter can be 1:8 into 3 ft based on the loads and span.
What are the two parts of the structural design process?
- Preliminary design stage
- Structural calculations and dimensioning
In architectural design, what does the general arrangement of a building typically determine?
The type of structure required to support it
What structural material was used for the Willis, Faber and Dumas building?
Reinforced concrete
What type of structural framework was required for the Rooftop Office in Vienna?
Skeleton framework of steel
How does the initial concept for a building influence its design?
It determines the overall form and the disposition of solid and void.
What are the four broad categories of decision-making in structural design?
- Relationship between architectural and structural design
- Selection of the generic type of structure
- Selection of structural material
- Determination of detailed form and layout
True or False: Structural decisions are often taken in a strict sequential order.
False
Who primarily determines the overall form of an architectural structure?
The architect or architectural team
What does the term ‘structure ignored’ refer to?
Designing architectural form without considering structural implications.
What materials allow for the creation of almost any architectural form?
Steel, reinforced concrete, and timber
Fill in the blank: The structural factor that allows materials like steel to be shaped into any form is their ability to resist _______.
tension, compression, and bending
What has historically influenced architects to limit themselves to simple shapes?
Cultural preferences for orthogonality and convenience in design
What defines a well-designed building according to some architects?
Resolution of conflicts between architectural program and structural consequences.
What was a significant reason for the lack of complex forms in 20th-century architecture?
Cultural ideologies favoring regularity and orthogonality
What is the implication of the relationship between structure and architecture?
It can take various forms, such as structure ignored, structure accepted, structure symbolized, and structural ‘high tech’.
How did the East Pavilion of the Groninger Museum demonstrate innovative construction techniques?
Major elements of the steelwork were manufactured using shipbuilding techniques.
True or False: Complexity in architectural forms is primarily limited by technical capabilities.
False
What is one reason complicated forms are avoided in building design?
Higher construction costs associated with complex geometries.
What is the primary reason for the high costs of vehicles like motor cars, sailing yachts, and aeroplanes?
The costs are primarily due to the fashioning of materials into complex shapes and configurations
The basic costs of materials are not the main contributor to the high costs of these vehicles.
How does the scale of a building affect its architectural form?
The larger the span, the more restrictive the structural constraints on form
Small spans allow for virtually unlimited freedom in form, while larger spans impose limitations.
What happens if a building’s form is determined without considering structural performance?
It may subject the structure to bending-type internal forces, resulting in inefficient use of structural material
High internal forces can compromise the feasibility of the structure.
What materials might be used for a structure with a small span (less than 1 meter)?
Materials like cardboard or papier mâché could be used
These weak materials are suitable for small-scale models.
What types of structures are appropriate for short-span buildings?
Simple structural forms composed of basic elements, such as timber beams or reinforced concrete beams
These forms are best for buildings without large interior spaces.
What is the relationship between structural complexity and span?
The larger the span, the greater the level of complexity justified due to the need for high structural efficiency
Conversely, simpler forms are appropriate for shorter spans.
What is the ‘structure accepted’ approach in architectural design?
It aims to produce a building where structural, aesthetic, and programmatic issues are given equal importance
Structures are not merely hidden but integrated into the overall design.
What historical examples illustrate the ‘structure accepted’ approach?
Greek temples, Roman basilicas, and Gothic cathedrals
Modern examples include buildings by Le Corbusier.
What is the main objective of the ‘structure symbolised’ approach?
To emphasize the structure visually as an essential element of the architectural vocabulary
This approach prioritizes aesthetic over technical performance.
How did the high-tech movement influence architectural design?
It often used steel frameworks and complex shapes for visual interest, emphasizing technical progress
This resulted in many buildings that were not well-engineered despite their high-tech appearance.
What challenges arise from using the ‘structure symbolised’ approach?
It may compromise the technical quality of the structural design due to aesthetic priorities
This can lead to technically flawed buildings despite their intended symbolism.
For what purpose could the ‘structure symbolised’ approach be adapted beyond Modernist ideals?
To celebrate sustainable architecture by highlighting energy and resource minimization in construction
This could develop a new architectural vocabulary focused on sustainability.
What is the ‘structure symbolised’ approach in architecture?
An architectural method that emphasizes the symbolic representation of structure, often highlighting sustainability and minimizing resource input.
This approach may lead to a new architectural vocabulary distinct from high-tech architecture.
What is the primary concern of the ‘true structural high tech’ approach?
The design of the structure is completely determined by structural requirements, often leaving little room for artistic expression.
It focuses on functionality and efficiency, typically used in buildings with significant structural demands.
Which materials are typically favored in ‘true structural high-tech’ architecture?
Reinforced concrete and steel
These materials are chosen for their ability to meet high structural demands while maintaining efficiency.
What architectural approach tends to dominate when aesthetic considerations outweigh technical ones?
‘Structure symbolised’ or ‘structure ignored’ approaches
These approaches often lead to structural geometries that may not be ideal.
What role does the designer play in the ‘structure symbolised’ approach?
The designer must have a clear awareness of the architectural statement intended by the building’s structure.
Distortion and exaggeration of the structure’s form are necessary to convey this statement clearly.
What does the term ‘form-active structure’ refer to?
Structures that derive their stability and efficiency from their shape and the forces acting upon them.
Examples include cable networks and reinforced concrete shells.
In what situation is ‘true structural high-tech’ most commonly applied?
When technical necessity makes it unavoidable, typically in buildings with significant structural loads.
Architects rarely choose this method unless required by the building’s structural demands.
What is the relationship between span and structure type?
As the span increases, more efficient types of structures must be specified to maintain a satisfactory strength-to-weight ratio.
This principle governs the selection of structure types in architectural design.
What are the three broad categories of structures for buildings?
- Form-active
- Semi-form-active
- Non-form-active
Each category has unique characteristics and applications based on the type of loads they are designed to resist.
What is the significance of the ‘structure ignored’ category?
The overall form of the building is determined without regard to structural requirements, often resulting in semi-form-active structures.
This category may limit the choices available to the structural designer.
What is the primary factor influencing the choice of structural material in architecture?
The relationship between structure and architecture, as well as the specific requirements of the building’s design.
This includes considerations of weight, load-bearing capacity, and aesthetic compatibility.
What does ‘span/depth ratio’ refer to?
The ratio of the span of a structural element to its depth, which impacts the efficiency and suitability of various structure types.
This ratio is critical for determining the performance of materials under load.
Fill in the blank: The __________ approach allows structural issues to dictate the architectural form completely.
True structural high tech
True or False: The ‘structure ignored’ approach often leads to the most efficient structural solutions.
False
This approach typically results in structures that do not adequately address structural efficiency.
What is a major consequence of prioritizing aesthetic considerations over technical ones in architecture?
The potential creation of buildings with unresolved qualities and inefficiencies in structural performance.
This often leads to the symbolic use of structure without fully understanding its technical implications.
What is the relationship between structure types and their potential maximum span?
The maximum span is related to the efficiency of the structure types.
Simple, solid rectangular cross-sections have lower maximum spans, while highly efficient forms like vaulted shells achieve the highest spans.
What types of structures are suitable for small spans (5 m)?
Virtually all structure types are available, including:
* Simple beams or slabs
* Arches
* Vaults
As the span increases, what happens to the choice of structure types?
The choice of structure types decreases as the span increases.
What is the span range suitable for basic post-and-beam types of structures?
5 m to 10 m for short-span structures.
What types of structures can achieve spans of up to 30 m?
Loadbearing-wall structures with ‘improved’ cross-sections, such as fin walls or diaphragm walls.
What is the typical span range for multi-storey post-and-beam frames?
5 m to 20 m.
What structural elements are used for spans greater than 20 m in multi-storey buildings?
Efficient types such as:
* Triangulated girders
* Coffered slabs
* Hollow-web steel beams
At what span range does the transition from semi-form-active to fully form-active structures occur?
40 m to 60 m.
What is a significant factor influencing the choice of structure type?
Cost.
What does structural efficiency often require?
Structural complexity, which can be costly.
How does the degree of regularity of a plan affect structure type preference?
Regular arrangements perform better and may accommodate more complex structures.
What type of structure is typically required for large areas of open space?
A frame structure.
What structural type is usually associated with full glazing of exterior walls?
Skeleton-frame structure.
What are the three most important factors in selecting the generic type of structure?
- Scale
- Internal planning
- External treatment
What are the four principal structural materials mentioned?
- Steel
- Reinforced concrete
- Masonry
- Timber
What type of structure favors the use of masonry or timber?
Loadbearing-wall structure.
Why is reinforced concrete rarely used for single-storey buildings?
High self-weight makes it unsuitable for small imposed loads.
What are the normal choices for a skeleton-frame structure?
- Steel and timber for single-storey frames
- Steel and reinforced concrete for multi-storey frames
What are the advantages of selecting steel as a structural material?
- High strength
- Appearance
- Speed of construction
Why might reinforced concrete be selected for a structure?
- Low cost
- Good durability
- Opportunities for complex geometries
What is the final step in determining the form of a structure?
Adapting one of the basic forms described in structural design.
What type of structure is used in the Willis, Faber and Dumas building?
Two-way-spanning flat slab structure of reinforced concrete
What is the significance of the square column grid in the Willis, Faber and Dumas building?
It provides support for the two-way-spanning slabs and accommodates a curvilinear plan
What type of loading does the flat-slab structure in the Willis, Faber and Dumas building accommodate?
High levels of uniformly distributed imposed load
Fill in the blank: The Florey Building has a _______ spanning floor deck.
one-way
What structural system was chosen for the Florey Building and why?
Beam/column framework due to the need for structural continuity and complex cross-section
What is the advantage of using reinforced concrete in the Florey Building?
It allows for a complex form while maintaining a straightforward construction process
How does the New City Library in Munster demonstrate the use of reinforced concrete?
It utilizes a reinforced concrete frame with vertical structures forming loadbearing walls
True or False: The New City Library has a simple structural arrangement despite its complex form.
True
What structural arrangement does the Exhibition and Assembly Building utilize?
A reinforced concrete framework with concentric circle plan
What is the primary consideration in the structural design process for architectural structures?
The architectural objectives set by the architect(s)
List the factors that influence the choice of structural material.
- Architectural objectives
- Site conditions
- Scale of the building
- Character of internal layout
Fill in the blank: The distinctive form of the Willis, Faber and Dumas building was made possible by a skilful adaptation of _______.
one of the basic forms of reinforced concrete structure
What does the term ‘structure accepted’ imply in the context of architectural design?
The structure meets technical requirements while accommodating architectural forms
What is the primary benefit of the mouldability of concrete in building design?
It allows for distinctive shapes and forms that are difficult to achieve with steel
What is the structural benefit of a flat-slab structure?
It provides strength through structural continuity over several bays
True or False: The structural continuity is less important in one-way spanning structures than in two-way spanning structures.
True
What does the term ‘loadbearing wall’ refer to?
A wall that supports structural loads in a building
How does the structural grid arrangement in the Exhibition and Assembly Building enhance its functionality?
It supports the floor slabs while accommodating voids in the design
Fill in the blank: The choice of a _______ framework was logical for the Florey Building due to its crescent-shaped plan.
beam/column
