Reinforcement and Minimum Thickness for Sockets with Cross Hole, Flat End and Long Wavy Rebar

Lifting System with Sockets

When using lifting inserts, precast elements must be provided with a minimum surface reinforcement (cf. table 1) and concrete must have a minimum strength of 15 MPa at first time of lifting.

Existing static-structural reinforcement may be taken into account. The user is personally responsible for further transmission of load into the unit.

Table 1: Minimum reinforcement

Lifting System with Sockets - Reinforcement and Minimum Thickness for Sockets with Cross Hole, Flat End and Long Wavy Rebar - Table 1: Minimum reinforcement

Reference	Longitudinal reinforcement FeE500		Surface reinforcement acier HA / FeE500
	[mm]	[mm]	[cm²/m]
12	Ø 10	850	1,31
14	Ø 10	850	1,31
16	Ø 10	850	1,31
18	Ø 12	850	1,88
20	Ø 12	850	1,88
24	Ø 12	850	1,88
30	Ø 16	1000	1,88
36	Ø 16	1000	1,88
42	Ø 16	1000	1,88
52	Ø 20	1200	1,88

This minimum reinforcement can be replaced by comparable stirrups with longitudinal reinforcement. Diagonal tension requires additional reinforcement (table 3).

For transmission of load into the concrete, a reinforcement stirrup of FeE500 is inserted through the cross hole of the lifting socket.

Contact of reinforcement and insert has to be ensured in suitable manner (binding wire, but no welding).

Lifting sockets must be used in units with minimum dimensions according to table 2.

Table 2: Minimum axis distance, edge distance, minimum thickness of unit

Reference	Minimum axis distance (a)	Minimum edge distance (b)	Minimum thickness of unit (c)
	[mm]	[mm]	[mm]
12	300	150	60
14	400	200	60
16	400	200	80
18	500	250	100
20	550	275	100
24	600	300	120
30	650	350	140
36	800	400	200
42	1000	500	240
52	1200	600	275

In case of lateral and diagonal tension, minimum reinforcement (table 1) must be strengthened by additional reinforcement (table 3 and 4).

Additional reinforcement must have pressure contact with the insert. Diagonal tension reinforcement is arranged in the opposite direction of that of tensile force.

Table 3: Additional reinforcement on diagonal tension (necessary if β ≥ 12,5°)

Lifting System with Sockets - Reinforcement and Minimum Thickness for Sockets with Cross Hole, Flat End and Long Wavy Rebar - Table 3: Additional reinforcement on diagonal tension

Reference	rebar Ø FeE500	L	Ø Bending diameter d_br
	[mm]	[mm]	[mm]
12	6	150	24
14	6	200	24
16	8	200	32
18	8	250	32
20	8	300	32
24	10	300	40
30	12	400	48
36	14	550	56
42	16	600	64
52	20	750	140

Table 4: Additional reinforcement on lateral tension (necessary if γ ≥ 7°)

Lifting System with Sockets - Reinforcement and Minimum Thickness for Sockets with Cross Hole, Flat End and Long Wavy Rebar - Table 4: Additional reinforcement on lateral tension

Reference	rebar Ø FeE500	L	H	Ø Bending diameter d_Br
	[mm]	[mm]	[mm]	[mm]
12	6	270	35	24
14	8	350	42	32
16	8	420	49	32
18	12	460	55	48
20	12	490	64	48
24	12	520	75	48
30	16	570	92	64
36	16	690	118	64
42	16	830	143	64
52	20	930	174	140

Tilt-up of slabs can lead to simultaneous diagonal and lateral tensions. Those cases request only lateral reinforcement and also cover diagonal tension.

Repeated tilt-down or tilt-up of the unit during installation requires a taking into account of lateral reinforcement.