G4 - Describe Shoring & Re-Shoring for Falsework Systems

Question 1

What is the slenderness ratio?

Answer 1

1:50 Typical ratio. of minimum thickness of post to unsupported height.

Question 2

Describe three ways shores are made adjustable:

Answer 2

1) Screw Jack
2) Ellis Clamp
3) Wooden Wedges

Question 3

Why are re-shores not fitted tightly to the concrete that they are supporting?

Answer 3

To not put undue pressure on concrete while reshoring.

Question 4

Describe a slab table.

Answer 4

Truss shoring, stringers, joists, plywood deck & finally screw jacks.

Question 5

What are fly forms?

Answer 5

Fly table or gang tables lifted by a crane.

Question 6

How are Aluma beams attached to false work?

Answer 6

Slotted bottom, and bolt aluma clip & nut.

Question 7

What is a mudsill for?

Answer 7

Distributes the weight.

Question 8

What is the process that is used to cycle the formwork and re-shores for a multi-story building:

Answer 8

1) Form
2) Shore the pour
3) Cure
4) Strip
5) RESTORE

Question 9

How should re-shores be placed when there are point loads above them?

Answer 9

Directly under point loads, also to support the slab.

Question 10

How should re-shores be placed when there are no point loads above them?

Answer 10

To support slabs and beams in rows to be braced.

Question 11

Two types of re-shoring systems:

Answer 11

Post & Scaffold.

Question 12

What components does falsework require?

Answer 12

1) Foundation, vertical & horizontal structural components, horizontal bracing in both directions and diagonal bracing.

Question 13

When is 4x4 timber used in falsework?

Answer 13

When elevations are varied and as re-shores to support the concrete as it cures.

Question 14

4x4 wooden restores should be cut how much shorter than the intended supporting length?

Answer 14

1 to 1 1/2” inches short, allow for wedges to adjust to desired height

Also to avoid stressing the green concrete by pounding a tight re-shore into place.

Question 15

Slenderness ratio formula:

Answer 15

Convert feet into inches and divide by 50

EX 18 ft post

18 x 12 = 216 INCH
216 / 50 = 4.32”

4.32 greater than the smallest dimension of post of 4”, so post needs lateral support.

Question 16

How does an Ellis Clamp work?

Answer 16

As the force is exerted onto the top of the shore, the right-hand side of the clamp is forced down. As the right-hand side tries to move down the clamp tightens up.

Question 17

Single telescope steel shore:

Answer 17

Often used as part of falsework. Shore head is used to accommodate a stringer and each shore braced at mid-point in both directions to resist bowing.

Question 18

All parts of scaffold shoring must be from same manuf. True or False?

Answer 18

True

Question 19

Scaffold shoring usually sits on a mudsill and is used to support:

Answer 19

Stringers that support the formwork

Question 20

Should formwork include a form removal process that allows the formwork to be stripped safely and efficiently?

Answer 20

Yes, so materials can be reused.

Question 21

The contractor must provide what:

Answer 21

1) Erection drawings
2) Supplementary instructions that clearly show all info. to accurately and safely assemble the concrete formwork, falsework, and re-shoring to the design requirements.

Question 22

The re-shoring plan should show:

Answer 22

1) Size and spacing of re-shores
2) Required concrete strengths necessary prior to the release of the falsework support & removal of any formwork
3) Detailed schedule of how the falsework and formwork are to be removed to prevent overloading of any part of the structure or other falsework and formwork

Question 23

Shoring place under recently stripped slabs concrete members, until they gain full strength, are called:

Answer 23

Re-shoring

Question 24

The amount of deflection is part of the building design and also part of the:

Answer 24

Erection drawings, required by WorkSafe BC

Question 25

Re-shores must not LIFT concrete but

Answer 25

Carry the additional live load that will be imposed on the concrete member by the formwork for the next floor of construction

Question 26

Days 1-3:

Answer 26

Column forms setup, braced, reinforcing installed then concrete is placed.

Question 27

Day 4-10:

Answer 27

Column form stripped
Flyform tables lifted into place
Additional slab formwork is built to complete the slab formwork between tables
Trades conduit, systems and rebar are installed,
Concrete placed and finish for second floor

Question 28

Day 11-14

Answer 28

Second-floor column form set up, braced, reinforcing installed and the concrete is placed.

Question 29

Day 15-23

Answer 29

Second floor column forms are stripped and column forms are set aside

Fly form tables then dropped and lifted onto 2nd floor, restores are immediately placed directly under the foot of the fly form tables
Extra re-shore is placed under the slab at mid point
Use chalk marks left on underside of the slab to position eshores
Formwork is finished and sub-trades complete work

Question 30

The size, type and spacing of re-shores will be specified on the:

Answer 30

Erection drawings

Question 31

Re-shores should be prevented from accidental dislodgement by supporting them on:

Answer 31

Mudsills at the bottom and lacing them together with bracing