Advanced single-strut modelling of lightweight in-filled RC frames: validation and seismic performance assessment

Area of Science:

• Structural Engineering
• Earthquake Engineering
• Computational Mechanics

Background:

• Accurate seismic performance assessment of reinforced concrete (RC) frames with masonry infills is critical.
• Modern lightweight infill systems (hollow clay bricks, gypsum blocks, autoclaved lightweight concrete) exhibit complex nonlinear behavior.
• Conventional modeling approaches struggle to capture the distinct failure mechanisms of these infill systems.

Purpose of the Study:

• To develop and validate an advanced single-strut macro-modeling framework for masonry-infilled RC frames.
• To accurately simulate the nonlinear behavior and seismic performance of various lightweight infill systems.
• To provide a reliable tool for performance-based seismic design and analysis.

Main Methods:

• Implementation of a single-strut macro-modeling framework in SAP2000.
• Development of material-specific nonlinear axial hinges calibrated against experimental data.
• Replication of distinct infill failure mechanisms: crushing (HCB), shear-sliding (GB), and slip-hardening (ALC).

Main Results:

• The calibrated model achieved high predictive accuracy (errors <10% in lateral capacity and initial stiffness).
• Hollow clay brick (HCB) infills significantly increased stiffness (471%) but showed brittle failure.
• Autoclaved lightweight concrete (ALC) panels offered superior ductility (µ=5.39) and energy dissipation.
• Gypsum block (GB) infills demonstrated seismic inadequacy due to abrupt strength degradation.

Conclusions:

• The proposed single-strut macro-modeling framework is a reliable tool for seismic analysis of infilled RC frames.
• It enables efficient comparative evaluation of different infill systems, considering stiffness-ductility trade-offs.
• The validated model supports performance-based design, reducing the need for costly full-scale testing.