1.0 Long Span Roof

Question 1

1. classify the roof based on structure

Answer 1

i) flat roof

ii) pitch roof

Question 2

2. list three(3) categories of roof system

Answer 2

i) lattice truss construction
ii) portal frame
iii) shell construction

Question 3

3. list the requirement application of long span roof

Answer 3

i) strength to bear the load
ii) stability to support the dead load
iii) durability for the expected life of a building
iv) less maintainance
v) fire resistance
vi) structure light in weight

Question 4

1. lattice roof purpose

Answer 4

to provide a visually attractive and structurally efficient solution for industrial buildings

Question 5

2. two(2) classification of lattice roof

Answer 5

i) lattice trusses

ii) lattice girders

Question 6

3. explain the component of lattice roof

Answer 6

i) column- to support the roof truss
ii) tie beam- to prevent the roof from spreading
iii) rafter- function as roof truss, to support the purlin or roof cladding
iv) bracing- providing rafter’s stability
v) purlin- supporting purlin’s installation
vi) side rail- providing frame’s stability
vii) roof cladding- function as roof covering
viii) connection- to connect two or more elements (column-rafter/tie beam-rafter/rafter-rafter)

Question 7

4. list eight(8) types of lattice roof

Answer 7

i) symmetrical pitch truss roof
ii) north light lattice steel truss roof
iii) multi span lattice steel roof
iv) cantilever lattice steel roof
v) space frame steel truss roof
vi) lattice steel girder roof
vii) space deck lattice steel truss roof
viii) turbular steel lattice rafter roof

Question 8

5) i) explain briefly the symmetrical pitch truss lattice roof

Answer 8

i) commonly used for medium and long span roof
ii) the frame form is triangle for natural light and ventilation
iii) has mild steel in rivets or welded together to support the light steel purlin
iv) purlin supports the roof and roof coverings
v) roof slope is determined by the type of roof coverings

Question 9

ii) north light lattice roof

Answer 9

i) has a symmetrical profile with the south facing slope pitched at 170° or more to the horizontal and north facing slope at around 60°
ii) the whole of the south slope is covered with profiled sheets and the whole north slope with glass or translucent plastic sheeting
iii) the span is 10m-15m

Question 10

iii)multi span lattice steel roof

Answer 10

i) to cover the large area and to meet the requirements of factory building design
ii) two or more bays of symmetrical pitch roof are used to limit; the volume of roof space; the length of the trusses
iii) to avoid closely spaced internal columns; a valley beam is used to support the roof trusses between the internal columns

Question 11

6. sketch i) two bay symmetrical pitch lattice roof

Answer 11

two bay symmetrical pitch lattice roof

Question 12

ii) two bay symmetrical lattice cantilever

Answer 12

two bay symmetrical lattice cantilever

Question 13

iii) north light lattice roof

Answer 13

north light lattice roof

Question 14

7. explain the chord members arrangements of lattice roof

Answer 14

i) the top chord of lattice structure follows the required slope of roof, but the bottom chord can either be parallel to the roof slope or be horizontal
ii) a horizontal bottom chord provides larger service zone, but results in bracing members of varying lengths
iii) a bottom chord parallel to roof slope result in bracing members of constant length, simplified fabrication, smaller overall dimensions for transport and an increase in the clear internal height at mid span

Question 15

8. explain the construction of lattice roof

Answer 15

i) all requirements of short, medium and long span are met by the lattice roof structures
ii) the members can be arrange to satisfy external cladding slope and internal requirements and at the same time, satisfy both strength and deflection requirements
iii) lattice form also provide the ability to support the internal service within the roof zone whilst at the same time keeping them accessible for maintainance

Question 16

9. explain the construction of north light lattice roof

Answer 16

i) has a symmetrical profile with the south facing slope pitched at 170° or more to the horizontal and north facing slope at around 60°
ii) the whole of the south slope is covered with profiled sheets and the whole north slope with glass or translucent plastic sheeting
iii) the span is 10m-15m

Question 17

10. explain the following connection of lattice roof component
    i) bolted

Answer 17

to connect the temporary eccentricity of the shear line between the centroid axis of rod bolt

Question 18

ii) welded

Answer 18

centroid of the weld is organised so that even with the centroid axis angles in the plane guest

Question 19

iii) gusset plat

Answer 19

to transfer between the joint and the thickness of the plate is determined based in the thickness of joint trusses

Question 20

11) sketch

i) bolted connection

Answer 20

bolted connection

Question 21

ii) gusset plate connection

Answer 21

gusset

Question 22

12) list the material used for construction of lattice roof

Answer 22

i) solid wood
ii) laminated wood
iii) steel
iv) steel pipe

Question 23

13) explain the sustainability of lattice roof

Answer 23

i) it is used on large and wide building, and also on a single storey commercial or industry building
ii) inside of building are open and less partitions wall
iii) building doesn’t contain walls or pillars
iv) open space/walling