PROFIS Design Guide: US-EN Summer 2021 | Page 155

Sustained Tension Load — Bond Strength

Results 0.55 ϕN _ba

Results ACI 318-14 Chapter 17 Provision Comments for PROFIS Engineering 0.55 ϕN _ba

17.3.1.2 For the design of adhesive anchors to resist sustained tension loads , in addition to 17.3.1.1 , Eq . ( 17.3.1.2 ) shall be satisfied .

0.55 ϕN _ba ≥ N _{ua , s}

( 17.3.1.2 )

Where N _ba is determined in accordance with 17.4.5 . 2 . 17.4.5 . 2 The basic bond strength of a single adhesive anchor in tension in cracked concrete , N _ba

, shall not exceed

N _ba

= λ _a т _cr π _da h _ef

( 17.4.5 . 2 )

PROFIS Engineering parameters for calculating N _ba :

N _ba

= λ _a т _kxxx α _{N , seis} πd _a h _ef

PROFIS Engineering calculations for N _ba when used to calculate the sustained load parameter 0.55 ϕN _ba

:

N _ba

=

( λ _a т _xxxx α _{N , seis} πd _a h _ef

) α _{N , seis}

17.2.6 Modification factor λ _a for lightweight concrete shall be taken as : Adhesive anchor bond failure per Eq . ( 17.4.5.2 ) ........................ 0.6 λ

where λ is determined in accordance with 19.2.4 . It shall be permitted to use an alternative value of λ _a where tests have been performed and evaluated in accordance with ACI 355.2 or ACI 355.4 .

Example : Example of a table in an ICC-ESR showing the following parameters for calculating N _ba

:

• т _kcr and т _{k , uncr}

— characteristic bond stress values

• α _{N , seis} — seismic reduction value

• d _a

— anchor element diameter

• h _ef — anchor effective embedment depth

The provisions given in ACI 318-14 Section 17.3.1.2 are used to perform a check for adhesive anchors subjected to sustained tension loads . The check consists of calculating a capacity ( 0.55ϕN _ba

), and comparing it to the highest ( factored ) sustained tension load ( N _{ua , s}

) acting on a single anchor within the anchor group . The strength reduction factor ( ϕ-factor ) in Eq . ( 17.3.1.2 ) corresponds to the parameter “ ϕ _bond

” in the PROFIS Engineering report . The parameter “ N _ba

” corresponds to the “ basic bond strength ” for a single adhesive anchor without any fixed edge influences . N _ba is calculated per Eq . ( 17.4.5.2 ); but an additional seismic modification factor that is derived from testing per the ICC-ES acceptance criteria AC308 is not given in Eq . ( 17.4.5.2 ), and must also be considered in the N _ba

-calculation . This seismic modification factor is designated “ α _{N , seis} ”, and is included in PROFIS Engineering N _ba

-calculations when seismic conditions are being modeled . However , since seismic load is not considered a sustained load , PROFIS Engineering divides out any α _{N , seis}

-value when calculating N _ba per Eq . ( 17.3.1.2 ).

Reference the Equations , Calculations and Results section of the report for more information on :

N _ba

:

Basic bond strength parameters and calculations for the sustained tension load check

Reference the Results section of the PROFIS Engineering report for more information on the following parameters :

ϕ _bond

:

N _{ua , s}

:

Strength reduction factor for bond Sustained factored tension load

ICC-ESR-3187 Table 14

DESIGN INFORMATION Symbol Units

Nominal Rod Diameter ( in ). 3 / 8 1 / 2 5 / 8 3 / 4 7 / 8 1 1-1 / 4

Temperature Range A

Temperature Range B

Temperature Range C

Permissible Installation Conditions

Characteristic bond strength in cracked concrete

Characteristic bond strength in uncracked concrete

Characteristic bond strength in cracked concrete

Characteristic bond strength in uncracked concrete

Characteristic bond strength in cracked concrete

Characteristic bond strength in uncracked concrete

Dry and water saturated concrete

ϕ _d

, ϕ _ws - 0.65

Reduction for Seismic Tension α _{n , seis}

- 0.88 1.0 1.0 1.0 1.0 0.97 1.0

155 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions