|LRT SYSTEM - LATERAL RESTRAINT TIE|
RESTRAINT -THE PROBLEM
There are many buildings where walls are in danger of moving or collapse because of inadequate lateral restraint of the wall to floor joists, ceiling joists or roof structure.The problem can be caused by one or a combination of several factors. For example:
-A decrease of wall stiffness and resistance to buckling and wind loading, can occur, with wall tie corrosion or insufficient wall ties installed during construction.
-Re-roofing using heavier materials would give increased vertical loads which could exceed the load-carrying capacity of the wall.
-The omission of lateral restraints or their failure in service can magnify the effects of other contributory causes.
Existing remedial systems involve disturbance of building occupants to provide access to the floor joists in order to fix bent steel straps to the wall and the joists.This disruptive and time consuming fixing method causes aggravation to the building occupant and is therefore unsatisfactory.
|THE BENEFITS||THE SOLUTION THE SPIT LRT|
REDIFIX have desgned and developed a lateral restraint tie system which is quick and easy to apply from the exterior of the building - no disruption from the inside is necessary.
The LRT is a solid A2, 300 Series stainless steel self drilling tie which saves fixing time dramatically. The only drilling is through the brick, block or masonry external wall with a I 3mm diameter drill. LRT guide tools are placed in the hole and the tie is driven under power through the guide tools, self-drilling into the joists.The Mac expander is independently set in the outer leaf of the brickwork to give a solid, high strength, lateral restraint to the wall.
Horizontal centres 600 to 1000 mm or as specified Structural Engineer.
|LRT SYSTEM - THE VARITIES||top|
expander version used for the majority of brick applications
- A2, 300 Series
Austenitic Stainless Steel
Diameter - 8mm x 2.3mm
pitch wood screw thread Pilot drilling point/diameter - 6mm x 2.3rpm pitch wood screw thread M6 thread on Mac Expander MB thread crimped for resin version
Length - Standard 1000mm to fix to two joists of maximum 500mm centres
Centres - long version can be manufactured to special order to suit wider centres, or to fix to three joists where this is required. Total length of the tie must allow for pilot point (45mm long) to pass right through innermost joist.
end version, where an M8 thread with crimped sections provides strong keying
points for BRC3 Resin.The resin is injected into the 13mm hole in the brickwork
after driving the lateral restraint tie into position.
Where the outer skin
of brickwork has been removed the LRTH hexagon nut and washer version,
can be used to restrain the inner skin relative to the joists.The outer
skin is then built using secondary wall ties, such as MAC FRAME CRAMPS.
Tests were performed in two, 33mm thick and two, 50mm thick, timbers spaced apart at 500mm centres.
NB. Prioir to installation, inspection must be carried out to ensure that no services are in line with the Lateral Restraint Tie position.
Drill through outer and inner wall leaves, using 013 x 460mm drill bit.
Insert two part LRT guide tool into hole.
Using threaded setting tool (TTM6S) and 1/4" square drive adaptor (SDSI4D)
Insert LRT into guide tool(LRTGT)
Select rotation only on the drill. You must also ensure that the drill has enough power to drive e.g. Spit 335, Drive through first joist.
Stop drilling machine and remove guide tool. Continue to drive the LRT through
second joist until mechanical expander has entered into the outer leaf of
the wall. Unscrew threaded setting tool off LRT.
5. With hex setting tool (FT5HS) and torque wrench (TB 100> set Mac Expander to 6.8Nm (51b.ft)
6. Seal the hole in the outer brickwork -job complete
NB - With SDS drilling machines SDS to 1/4" square drive adaptor (SDSI4D) is needed.
|SETTING TOOLS AND ACCESSORIES||top|
LRT Guide Tool
FT5HS Hexagon Setting Tool
SDSI4D 1/4" Square Drive
TTM6S Threaded Setting Tool**
TB 100 Preset Torque Wrench
Use drilling machine
model Spit 335 for drilling hole through brick work and driving LRT.