Superstructure Frames

Question 1

In-situ

Answer 1

Built at an element’s final position, as opposed to being manufactured elsewhere.

Question 2

Frame skeleton

Answer 2

A rectangular frame structure made of several elements joined together

Question 3

Modern methods of construction (MMC)

Answer 3

Range of techniques involving off-site manufacture to minimise construction time on-site

Question 4

Formwork

Answer 4

A temporary structure designed to contain fluid concrete

Question 5

Beam

Answer 5

A structural element that supports the weight of floors, ceilings and roofs of a building and transfers the load to a vertical load bearing element

Question 6

Lintel

Answer 6

A horizontal support used to span an opening in a wall or between two vertical supports

Question 7

Column

Answer 7

A vertical structural member intended to transfer a compressive loadc

Question 8

Composite construction

Answer 8

Construction involving multiple dissimilar materials - meant to increase stength, aesthetics, and environmental sustainability

Question 9

Mass structure

Answer 9

Solid structures that rely on their own weight to resist loads (like dams)

Question 10

Shell structures

Answer 10

Are assembled to make one piece. Mostly made from thin sheet material (making them light). Concrete architecture and cars are good examples of shell structures

Question 11

Frame structures

Answer 11

Made from many small parts, joined together. EG stadiums, architectural designs etc

Question 12

skeleton frames

Answer 12

Series of rectangular frames placed at right angles to each other -loads are transmitted from member to member until they are transferred to the foundations. Material type depends on site conditions, material availability, time, prefernece.

Question 13

In-situ reinforced concrete frames

Answer 13

All the elements are constructed on-site using steel reinforcement bars and wet concrete

Question 14

Why does concrete need to be reinforced with steel?

Answer 14

Concrete resists compressive stress but is weak in resisting tensile stress. Tensile stress is lengthening stress

Question 15

Tension

Answer 15

Stretches or pulls apart

Question 16

Compression

Answer 16

shortens or crushes

Question 17

Shear

Answer 17

Pushes parts in opposite directions

Question 18

Bending

Answer 18

Stretches and squashes at the same time

Question 19

Torsion

Answer 19

twists

Question 20

Formwork

Answer 20

AKA shuttering, temporary design to contain fluid concrete. Formed into required shape to support concrete until it cures and can be self-supporting. Most commonly timber

Question 21

In-situ reinforced concrete frame advantages (3)

Answer 21

1. Fire protection built into material, 2. Concrete can be moulded into any shape, 3. Cash flow advantages due to low initial costs

Question 22

In-situ reinforced concrete frame disadvantages (3)

Answer 22

1. Curing time required slows construction, 2. Potential for quality issues on-site, 3. Lots of temporary works required

Question 23

When to use in-situ concrete frame?

Answer 23

Any framed building, but typically one-off projects and buildings with non-standard shapes

Question 24

Precast reinforced concrete frames

Answer 24

Factory produced to EXACT specs. Erected using different methods for connecting the pieces.

Question 25

Precast concrete frames advantages (4)

Answer 25

1. Efficient use of reinforced concrete, 2. Curing periods can be accelerated in the factory, 3. Factory is a quality controlled environment 4. The system is unaffected by weather

Question 26

Precast concrete frames disadvantages (3)

Answer 26

1. Requires on site crane, 2. Maximum sizes limited by transport restrictions, 3. There could be issues with assembly in high winds

Question 27

Where to use precast concrete frames?

Answer 27

Anywhere, but particularly suited to where there is much repetition.

Question 28

Steel frames for multi-storey

Answer 28

one of the most common. Fabricated off-site and assembled/attached to pad foundations using bolted connections

Question 29

How does expensive steel become economically competitive? (5)

Answer 29

1. Material properties, 2. Optimum in reducing deadweight, 3. Prefabrication reduces time and labour costs, 4. High standard of dimensional accuracy, 5. Economically competitive used as a composite construction

Question 30

Universal beams

Answer 30

Capital I shape (not that I) - thickness of web is critical to resist buckling, and depth of web important to resist bending. For columns, this is typically thicker to resist buckling

Question 31

How do steel frames distribute load? (2)

Answer 31

1. Joints rigid - allows bending forces to be transferred to the columns. 2. This reduces beam depth and saves on steel, although costs for joints increase because the joints have to be strong.

Question 32

Bracing connection

Answer 32

Used in steel frames to join beams together. Essential that bracing is installed as the frame progresses, to avoid racking failure

Question 33

Erection of structural steelwork safety points (4)

Answer 33

1. prepping working area, and restricting access, 2.Mobile elevating work platforms (MEWPs) 3. PPE including fall arrest safety harness and lanyard, 4. Installing edge protection and fall arrest netting across entire area BEFORe construction

Question 34

Steel frame - sequence of assembly (6)

Answer 34

1. Erect 2 floor levels of steelwork, 2. Fit safety nets to underside of first-floor, 3. Install metal decking/precast concrete to first floor, 4. Fit safety nets to underside of second floor, 5. install metal decking to second floor, 6. repeat 2 to 6 until complete.

Question 35

Steel frames advantages (5)

Answer 35

1. Fast erection phase, 2. Off-site quality-controlled fabrication, 3. Standardised sections enable economies of scale for production, 4. Recycling, 5. Creates a strong structure

Question 36

Steel frames disadvantages (4)

Answer 36

1. Steel loses 50% strength in fires, 2. Need secondary fire protection finish, 3. Need to be treated to prevent corrosion from rust, 4. Repainting is required in external exposed locations EG bridges

Question 37

When to use steel frames?

Answer 37

Almost universal in the UK.

Question 38

Slim-floor construction

Answer 38

Fast, innovative, economical. Combines prefab slabs with built-in steel beams, integrating steel beams into the floor. Fire resistant and limited floor thickiness - an efficient use of materials combined with light elements

Question 39

Composite construction

Answer 39

Multi storey building, takes a variety of forms and becoming more prevalent. Structural steel sections and reinforced concrete are combined. EG the steel frame is encased in concrete. EG the shard

Question 40

Timber frame

Answer 40

Mostly used for domestic construction. Panel construction approach used, prefab offsite with light timber sections stiffened with a wood based board material. Also used in volumetric construction for temporary buildings

Question 41

Timber frame advantages (4)

Answer 41

1. Sustainable, 2. Cheap, 3. Structures can be occupied sooner as drying time is not required, 4. The lighter construction means savings on foundations

Question 42

Timber frame disadvantages (4)

Answer 42

1. Limited to six storeys, 2. Installation in high winds can be dangerous due to lighter weight and larger area of panels, 3. Timber decay with moisture can occur, 4. Design scepticism

Question 43

When to use steel frames?

Answer 43

Repetitive modular buildings EG hotels/apartments

Question 44

Portal frame

Answer 44

Type of steel frame, using sloping beams and columns, the rafters transfer roof loads to the stanchion, which can be bolted to the pad foundation. As there will be no internal columns, the ridge should be reinforced.

Question 45

What to consider when deciding on a frame? (7)

Answer 45

1. Site costs - financial return paramount so speed is key, 2. Steel or precast concrete - allow for maximum prefab offsite while foundation is constructed = more speed. 3. Client’s cash flow - slower forms of construction can reduce cash requirement, 4. Construction costs, 5. Pre cast or insitu? 6.Maintenance (Steel/in-situ low maintenance, precast is higher needing joint inspection) 7. Environmental concerns