Authorization Criteria for Undercut Type Mechanical Expansion Anchors (MEA) List

Revised: 11/4/2022

Undercut Mechanical Expansion Anchors (Undercut MEA) shall meet the following criteria for inclusion into the Authorized Materials List (AML).

  • Meets testing requirements in the American Concrete Institute (ACI) 355.2, Qualification of Post-Installed Mechanical Anchors in Concrete. It must have a current International Code Council - Evaluation Service Report (ICC-ESR).
  • The ICC-ESR must indicate that the following criteria are met:
  1. Meets the following minimum tensile strengths:
  • Tensile Yield Strength, fya = 60 ksi.
  • Tensile Ultimate Strength, fu = 90 ksi.
  1. Yielding of the steel element of the Undercut MEA is ductile per ACI 318.
  2. Is corrosion resistant, equivalent to AISI Type 316. This includes all parts of the Undercut MEA which includes, but are not limited to, anchor rod, expansion sleeve, expander cone, hex nut(s), and washer(s).
  3. Can be installed in the following locations and situations:
  • Concrete with a compressive strength between 2500 psi and 8500 psi.
  • Without supplemental concrete reinforcement
  • Where concrete cracking may develop
  • Horizontal, vertical, and overhead locations
  1. Can be installed under all weather conditions (Ex.: temperature, moisture/saturation, etc.).
  2. When installed, the Undercut MEA can:
  • Be loaded under sustained tension
  • Withstand dynamic loading (Ex., wind and seismic)
  1. Product includes method to confirm proper installation (Ex., bolt marks, breakaway indicators, measuring tools, etc.).
  2. Meets the criteria in Table 1: Performance Criteria Based on Anchor Diameter.
Table 1: Performance Criteria Based on Anchor Diameter
Anchor Diameter (1)

Effective Embedment Depth


hef (3)

Concrete Thickness

ha (3)

Edge Distance

ca,min (3)

Anchor Spacing

s (3)

3/8" (10mm)3.9" or more7-1/8" or less3-1/8" or less4" or less
1/2" (12mm)4.9" or more8" or less4" or less5" or less
5/8" (16mm)7.4" or more11-7/8" or less5-7/8" or less7-1/2" or less
3/4" (20mm)10" or more12" or less6" or less7-1/2" or less


  1. The Undercut MEA size required (diameter and effective embedment depth) and the structural capacity of an individual Undercut MEA anchor or anchor group shall be determined based on ACI 318-14, or later editions. Refer to the Division of Engineering Service’s Structural Design Alert – Anchorage to Concrete, dated 5/11/2020.
  2. The ESR report must include parameters that meet these criteria for a Stud MEA to be on the Authorized Material List (MEA).
  3. See ACI 318.
  4. See Figure 1: Undercut MEA Anchor Group.
Figure 1: Undercut MEA Anchor Group
Figure 1: Undercut MEA Anchor Group


Caltrans contact: Joe Harline, (916) 206-4373,