POST-INSTALLED REBAR DESIGN FOR DEVELOPMENT LENGTH AMBIENT TEMPERATURE
The following tables show calculated development lengths per ACI 318 Chapter 25 or CSA A23.3 Chapter 12 for applications not considering fire exposure ( ambient temperature ). Refer to the Hilti North American Product Technical Guide : Post- Installed Reinforcing Bar Guide , dated November 2022 ( Rebar Tech Guide ), for more information on rebar development for post-installed rebar .
For rebar development considering fire exposure , the development length may need to be increased based on the temperature in the concrete for the specified rebar cover and fire duration . Refer to Figure 5 of this section and Section 2 of this document to determine the development length needed for the fire exposure condition .
Table 3 — Calculated tension development and Class B Splice development lengths for ASTM A615 / A706 rebar in walls , slabs , columns , and footings per ACI 318 Chapter 25 for Hilti HIT-FP 700 R , not considering fire
exposure 4 , 5 , 6
Rebar size
# 3 c b
+ K tr
d b
Min . edge dist . in . 1 Min .
spacing in . 2 l d in .
Concrete compressive strength ƒ ́c ≥ 2,500 psi 3 Gr . 40 rebar
Class B splice in . l d in .
Gr . 60 rebar
Class B splice in .
2-1 / 4 2 12 12 12 14 # 4 2-3 / 4 2-1 / 2 12 12 14 19 # 5 3 3-1 / 4 12 16 18 23 # 6 3-3 / 4 3-3 / 4 14 19 22 28 # 7 2.5
4-1 / 2 4-1 / 2 21 27 32 41 # 8 5 5 24 31 36 47 # 9 5-1 / 4 5-3 / 4 27 35 41 53 # 10 5-3 / 4 6-1 / 2 30 40 46 59 # 11 6-1 / 2 7-1 / 4 34 44 51 66
1 Edge distance is determined using the minimum cover specified by ACI 318 Ch . 25 with an additional 6 % of the development length per suggestions for drilling without an aid per Hilti Rebar Tech Guide Section 3.3 . Smaller edge distances may be possible , for which development and splice lengths may need to be recalculated . For further information on required cover see ACI 318 , Sec . 20.5.1.3.1 . 2 Spacing values represent those producing c b
= 5 d b rounded up to the nearest 1 / 4 in . Smaller spacing values may be possible , for which development and splice lengths may need to be recalculated . For further information on required spacing see ACI 318 Sec . 25.2 .
3 The development length is the same for all concrete compressive strengths as it is not permitted to increase the capacity value of ƒ ́c used in the development length equations beyond 2,500 psi .
4 ψ t = 1.0 ; ψ e
= 1.0 for non-epoxy coated bars ; ψ s = 0.8 for # 6 bars and smaller bars , 1.0 for # 7 and larger bars ; ψ g
= 1.0 , See ACI 318 , Sec . 25.4.2.4 . 5 Values are for normal weight concrete . For sand-lightweight concrete , multiply development and splice lengths by 1.18 , for all-lightweight concrete multiply development and splice lengths by 1.33 . See ACI 318 Sec . 19.2.4 . 6 Development and splice length values are for static design . Seismic design not applicable for HIT-FP 700-R .
Table 4 — Calculated tension development and Class B Splice development lengths for CSA-G30.18 rebar in walls , slabs , columns , and footings per CSA A23.3 Clause 12 for Hilti HIT-FP 700 R , not considering fire exposure 4 , 5 , 6
Rebar size d cs + K tr
Min . edge dist . mm 1 Min .
spacing mm 2
10M
Concrete compressive strength ƒ ́c ≥ 20 MPa 3 l d mm
Gr . 400 MPa
Class B splice mm
60 50 300 380 15M 70 75 410 540
20M |
2.5 d b |
80 |
100 |
510 |
660 |
25M |
|
120 |
125 |
820 |
1060 |
30M 130 150 960 1250
1 Edge distances are determined using the minimum cover specified by CSA A23.3 with an additional 6 % of the development length per suggestions for drilling without an aid per Hilti Rebar Tech Guide Section 3.3 . Smaller edge distances may be possible , for which development and splice lengths may need to be recalculated . For further information on required cover see CSA A23.3 Table 17 .
2 Spacing values represent those producing d cs = 5 d b rounded up to the nearest 10mm . Smaller spacing values may be possible , for which development and splice lengths may need to be recalculated . For further information on required spacing see CSA A23.3 Sec . 6.6.5.2 .
3 The development length is the same for all concrete compressive strengths as it is not permitted to increase the capacity value of ƒ ́c used in the development length equations beyond 20 MPa .
4 k 1 = 1.0 ; k 2
= 1.0 for uncoated reinforcement ; k 3 = 1.0 for normal density concrete ; k 4
= 0.8 for 20M bars and smaller bars , 1.0 for 25M and larger bars ; See CSA A23.3 Clause 12.2.4 . 5 Values are for normal weight concrete . For lightweight concrete , multiply development and splice lengths by 1.3 . 6 Development and splice length values are for static design . Seismic design not applicable for HIT-FP 700-R .
12 May 2023