LAPPING OF REINFORCEMENTS

Laps are used to transfer stress across discontinuous steel reinforcements.

In order to do so, the lap must be sufficiently long to develop the stresses required.

a. Full Yield Strength Lap

+ According to international Standard: BS, ASTM, AS/NZ, SS. TCVN, two cross weilds are sufficient to transfer the full yield strength for Plain weldmesh. 

+ As for Rib wire fabric, the lap length could be reduced depending on the number of welded intersection present with the lap.

+ If overlap is not specified, full strength lap should be provider.

b. Half Yield Strength Lap

+ Half yield strength laps are sometime permitted for side laps in one way slaps.

+ Commonly used for side laps across beams or top reinforcement.

+ However, this must be specified by the designer.

c. Flying End Lap

+ In-plane lapping where one sheet is provided with flying end without welded intersections.

+ The lap length is determined as for rebar (plain or deformed wires) based on bond stress.

+ It is used to reduce thickness of the lapping point. Commonly used for Rib Wire Fabric.

 

ANCHORAGE

In Pratice, 12 x wire diameter or d/2 whichever is greater is used for bottom fabric anchorage into the supports.

The main and cross wire anchorage commonly used for mesh are shown in Figure 1.