BEHAVIOR OF POST-INSTALLED ANCHORS TESTED BY STEPWISE INCREASING CYCLIC LOAD PROTOCOLS.

Area of Science:

• Structural Engineering
• Earthquake Engineering
• Materials Science

Background:

• Cyclic loads characterize seismic actions on structures and anchorages.
• Current seismic qualification of post-installed concrete anchors relies on American Concrete Institute (ACI) 355 standard, which has limited scientific basis for its test protocols.

Purpose of the Study:

• To develop and utilize novel test protocols with stepwise-increasing load amplitudes for a more realistic seismic performance evaluation of concrete anchors.
• To investigate the load-displacement behavior of common anchor types in cracked concrete under cyclic tension and shear actions.

Main Methods:

• Implementation of newly-developed cyclic load test protocols with stepwise-increasing load amplitudes.
• Testing of common post-installed concrete anchor types under simulated seismic conditions (cyclic tension and shear).
• Analysis of anchor load-displacement behavior in cracked concrete, considering various crack widths.

Main Results:

• Anchors exhibited robust performance under cyclic tension, even with crack widths exceeding ACI 355 requirements.
• Low cycle fatigue was identified as a critical factor significantly influencing the seismic performance of anchors subjected to cyclic shear actions.

Conclusions:

• The newly-developed test protocols provide a more realistic assessment of anchor seismic performance compared to existing standards.
• Findings highlight the need to consider low cycle fatigue in seismic design and qualification of concrete anchors, particularly for shear loading scenarios.