ACI 318-19 Changes to the Concrete Design Standard-Anchorage

Video Transcription

Video Summary

The video presentation addresses changes in the ACI318-19 standard related to anchorage to concrete. Key updates include the incorporation of screw anchors and shear lugs into the Anchorage to Concrete chapter, aligning it with other member chapters in the code. Screw anchors, now included, need pre-qualification according to ACI 355.2, with emphasis on effective embedment depth critical for their performance. Similarly, shear lugs have been added to enhance shear strength for concrete attachments. While offering predictable load paths and eliminating field welding, shear lugs can increase construction costs and complexity. The presentation discusses the bearing and breakout failure modes of shear lugs, alongside practical design calculations following the updated code. For shear lugs, both effective bearing area and specific load resistance factors are defined. A detailed example from the Reinforced Concrete Design Manual shows how shear lugs can be used to potentially reduce anchor bolt sizes and simplify design. However, if concrete breakout is likely, shear lugs may not always be beneficial for shear load capacity. Overall, these code additions provide a framework for advanced anchorage solutions in concrete structures.

Keywords

ACI318-19

screw anchors

shear lugs

anchorage to concrete

effective embedment depth

bearing and breakout failure modes

Reinforced Concrete Design Manual