AAC infill improved ductility more than clay masonry in RC frames

What the study found: Reinforced concrete frames infilled with autoclaved aerated concrete (AAC) blocks and clay bricks both increased lateral strength by about 60%. The AAC infill improved ductility more than the brittle clay infill.

Why the authors say this matters: The study suggests AAC blocks, described by the authors as a novel and environmentally friendly material, may be a useful alternative to traditional clay masonry infill in seismic-resistance applications. The findings indicate the enhanced reinforcing steel and the infill type both relate to the frame's cyclic response.

What the researchers tested: Three 2/3-scale reinforced concrete frames were tested under cyclic lateral loading. The frames used an advanced type of reinforcing steel, and the study also used numerical macromodeling of the infill panel with multi-strut and single-strut models in SeismoStruct and SAP2000, plus concentrated and distributed plasticity approaches for the RC elements.

What worked and what didn't: Both infill types contributed roughly equally to lateral strength, with about a 60% increase. The AAC infill performed better than the clay infill in ductility enhancement. The multi-strut macromodel was more accurate than the single-strut model in reproducing hysteresis behavior, and trilinear and quadlinear backbone curves were developed for the clay and AAC infills, respectively.

What to keep in mind: The abstract describes tests on only three 2/3-scale frames, so the scope is limited. It also notes that accuracy depended on parameters such as strut width, post-cracking degradation rate, shear-to-axial stiffness ratio, and strain at peak stress, but does not provide broader limits beyond the study setup.

Key points

• AAC and clay infills each increased lateral strength by about 60%.
• AAC infill improved ductility more than clay masonry infill.
• Three 2/3-scale reinforced concrete frames were tested under cyclic lateral loading.
• A multi-strut macromodel matched hysteresis behavior better than a single-strut model.
• Key modeling parameters included strut width, post-cracking degradation rate, and shear-to-axial stiffness ratio.