ACI CODE-355.2-22, published by ACI Committee 355 in 2022, is a 102-page document that prescribes testing programs and evaluation requirements for post-installed mechanical anchors in concrete, including expansion anchors, undercut anchors, and screw anchors used in ACI 318 structural applications under static or seismic loads in tension, shear, or combined load [S1].
Anchor categories established by the standard (Category 1 through 3) feed ACI 318-19 Chapter 17 capacity reduction factors and design parameters, so any test report that claims ACI 355.2 compliance is, in effect, qualifying the part for code-stamped design [S1][S3].
Crack-Width Tension Tests: 0.012 in., 0.020 in., and Cycled Cracks
Three anchor test types run inside concrete cracks, as spelled out in ACI 355.2 and its adhesive-anchor counterpart ACI 355.4: (1) static tension loading in 0.012- and 0.020-inch-wide cracks, (2) reliability tension tests with cycled crack-opening width, and (3) an optional seismic tension test in a 0.020-inch-wide crack [S4].
The test sequence starts by initiating a hairline crack (width under 0.002 in.) in the test member, drilling the anchor hole perpendicular to the surface so the anchor axis lies in the crack plane, installing per the Manufacturer's Printed Installation Instructions (MPII), opening the crack to the required width, and then loading to the ACI 355.2 procedure; only anchors passing these requirements are permitted where crack development may occur in service [S4]. Passing the optional seismic test additionally qualifies the anchor for Seismic Design Categories C, D, E, and F [S4]. For the broader cracked-concrete qualification framework, see the cracked-anchor testing primer for how the same crack-width logic propagates into ACI 318-19 Chapter 17 capacity factors.
Reliability Tests: Installation Torque, Concrete Strength, and Drill-Bit Tolerances
Chapter 9 of ACI 355.2-22 organizes reliability tests around the field conditions that most often produce premature anchor failure: reduced installation effort (e.g., installer under-torques the nut), low-strength concrete paired with a worn (oversized) drill bit, high-strength concrete paired with an undersized bit, repeated load, cycled crack opening, screw-anchor brittle-failure sensitivity, and screw-anchor setting-method robustness [S1].
Each row of Tables 5.1a and 5.1b maps a specific test to a specific simulated field abuse; for example, Test 4 (Table 5.1a) drops the installation torque, Test 5 (Table 5.1a) drops the concrete strength and increases the drill bit, and Test 6 (Table 5.1a) raises concrete strength and decreases the bit [S1]. A North Carolina State University pull-out and shear study followed the ACI 355.2 test program to isolate the effect of installation torque on anchor strength, quantifying how much capacity is lost when a torque-controlled expansion anchor is set below the MPII value [S6]. Engineers selecting expansion anchors for vibration or fatigue-loaded equipment should weigh Test 7 (repeated load) and Test 9 (cycled crack) data alongside the static tension numbers; reference data on holding-strength service-condition protocols helps frame the higher-temperature end of the same reliability conversation.
Seismic Tension Test: 1.6 N_eq Residual Strength Benchmark
For Seismic Design Category C-F applications, ACI 355.2-22 calls for a simulated earthquake tension test regimen (cyclic and monotonic loading) on torque-controlled expansion anchors installed in cracked concrete. A 2025 experimental study published in Engineering Structures reported that an enhanced torque-controlled expansion anchor completed the cyclic loading regimen with no damage to any anchor, and recorded an average residual tensile strength across all anchors that exceeded the 1.6 N_eq evaluation standard during the monotonic test, with concrete breakout as the dominant failure mode [S2].
The 1.6 N_eq threshold is the key acceptance line for the seismic residual-strength metric and is the number to watch when comparing published seismic qualification reports; anchors that fall below it cannot be specified for SDC C-F regardless of how well they do on the static tension tests [S2]. The same seismic logic is applied to expansion joints in fire-water and seismic piping, where the anchor sees a similar cyclic tension regime; the expansion-joint design boundary discussion covers the joint-side counterpart to the anchor-side qualification.
Acceptance Criteria: What the Numbers Have to Hit
Reference tension tests (Chapter 8) establish baseline mean and characteristic capacity from a controlled population; service-condition tests (Chapter 10) then check that the anchor retains enough capacity at the design load level under field-realistic installation and crack conditions; the ratio between the two drives the capacity reduction factor ACI 318-19 assigns to the part [S1].
Independent testing is the default: ACI 355.2-22 requires that the qualification program be run primarily by an independent testing and evaluation agency, not by the manufacturer alone, and Section 5.4 forces a re-qualification trigger whenever a manufacturer changes a critical characteristic (e.g., sleeve geometry, bolt grade, expansion-segment material) [S1][S3]. A practical comparison of the test types against their governing criteria:
Reference tension (Ch. 8): baseline capacity, no spacing or edge effect; used to derive characteristic resistance in uncracked and cracked concrete.
Reliability tension (Ch. 9): reduced torque, oversize/undersize bits, low/high concrete strength, repeated load, cycled crack; acceptance is a minimum fraction of reference capacity retained.
Service-condition tension (Ch. 10): in-place installation, design load level, sustained and cyclic service regimes; acceptance is that no anchor fails below the design load after the field abuse.
Seismic tension (optional, in cracked concrete): simulated earthquake cyclic loading plus monotonic pull; acceptance is residual strength at or above 1.6 N_eq and ductile, non-brittle failure mode [S1][S2].
Concrete Substrate and Where the Standard Stops
ACI 355.2-22 qualification is run on normal-weight and lightweight concrete that meet pertinent ACI and ASTM requirements; the standard does not, on its own, cover shotcrete or other placement-method-specific substrates, and most expansion-anchor manufacturers therefore do not publish permitted load ratings, installation torques, or other design data for shotcrete bases, instead recommending on-site testing or an engineering judgement by the responsible designer [S3].
The substrate scope also rules out most masonry by default, because ACI 355.2 was written for concrete; cracked-masonry anchor qualification sits under a separate Concrete and Masonry Anchor Manufacturers Association (CAMA) procedure using threaded-rod adhesive systems in grout-filled CMU walls, as documented in the 2019 Structure Magazine testing program [S4][S7]. Where a project crosses from concrete to a different substrate, the ACI 355.2-22 report alone is not enough; the specifier must layer on the substrate-specific data, and a related note on chemical-anchor qualification bounds explains how the adhesive-anchor sister standard (ACI 355.4) handles the same boundary in reverse.
Specifying an Expansion Anchor by ACI 355.2-22 Report
A specifier who wants a code-recognized expansion anchor should request the ACI 355.2-22 evaluation report (or its ACI 355.2-07/-19 predecessor where still valid), confirm the Category 1, 2, or 3 assignment, check cracked-concrete use, and for SDC C-F confirm that the seismic test row of the report shows residual strength at or above 1.6 N_eq [S1][S2][S4].
Field-side controls that fall out of the report and onto the installer: torque to the MPII value, use the drill-bit diameter and type listed in the report, respect minimum spacing and edge distance, and re-torque or re-qualify if the substrate turns out to be shotcrete, masonry, or any other material outside the report's tested scope [S3][S6]. Tracking signals worth watching through 2026: any successor code cycle to ACI 318-19 Chapter 17 that revises the Category 1/2/3 reduction factors, and any ICC-ES or IAPMO UES evaluation report updates that re-tier existing expansion anchors against the ACI 355.2-22 cracked-concrete and seismic rows.
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