⚡ electrical engineering

Comparative Numerical Evaluation of the Seismic Behavior of the Steel Framing System and Confined Masonry for a Single-Family Dwelling in Peru: A Computational Modeling Study

This computational study demonstrates that, under specific Peruvian seismic conditions and geometric constraints, a Steel Framing system is a technically viable lightweight alternative to confined masonry for single-family dwellings, as both systems satisfy the E.030 seismic safety standards despite the masonry exhibiting greater lateral rigidity and base shear.

Original authors: JULIAN ÑAUPA TAPULLIMA, PAUL RICARDO PRUDENCIO GALVEZ

Published 2026-08-11

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CC BY 4.0

Original authors: JULIAN ÑAUPA TAPULLIMA, PAUL RICARDO PRUDENCIO GALVEZ

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine the ground beneath our feet as a giant, unpredictable trampoline. Sometimes, it bounces gently; other times, it shakes with enough force to send a house tumbling. In places like Peru, where the earth sits on a volatile edge of the planet's crust, this shaking is a constant reality. When the ground moves, buildings have to move with it, but they must do so without falling apart. Engineers are like the architects of safety, constantly asking: "What kind of house can dance with the earthquake without tripping?"

To answer this, they look at two very different "dancers." The first is Confined Masonry, the traditional heavyweight champion. Think of it as a house built from heavy bricks and reinforced with concrete columns, like a sturdy, rigid suit of armor. It's heavy, stiff, and relies on its mass and solidity to resist the shake. The second dancer is Steel Framing, a modern lightweight contender. Imagine a house built from a skeleton of thin, galvanized steel studs, similar to the frame of a high-tech tent or a very strong, flexible birdcage. It's incredibly light and flexible. The big question isn't just which one is stronger, but which one handles the specific rhythm of a Peruvian earthquake better. Does the heavy armor hold its ground, or does the flexible frame sway and survive?

This study dives into that exact question, but instead of building two real houses and shaking them until they break (which would be expensive and messy), the researchers built two perfect digital twins inside a powerful computer program called ETABS 22. They simulated a single-story house in Lima, Peru, and subjected both the brick-and-concrete version and the steel-frame version to the same virtual earthquake rules defined by the country's safety standards.

The results were a fascinating dance of numbers. The heavy Confined Masonry house turned out to be the stiffest dancer. It barely wobbled, with a "sway time" (called a period) of just 0.150 seconds. Because it was so stiff, it felt the earthquake's full force, generating a massive push at its base (base shear) of 35.2 kN. It stayed very safe, with a maximum wobble (interstory drift) of only 0.0031, which is well below the safety limit of 0.005.

The Steel Framing house, on the other hand, was the flexible dancer. Because it was so much lighter, it swayed more freely, taking 0.280 seconds to complete a sway cycle—nearly twice as long as the masonry house. This flexibility meant it didn't feel the earthquake as hard; the push at its base was only 26.6 kN, about 32.3% less than the brick house. However, because it swayed more, its wobble was larger, reaching 0.0048 in one direction. This is still safely under the 0.005 limit, but it was much closer to the edge than the brick house.

Here is the twist: while the brick house barely moved, the steel house had to work harder internally to handle that movement. The individual steel studs in the frame had to deal with bending forces that were 190% higher and shear forces 74% higher than the concrete columns in the brick house. It's like the brick house stood still while the steel house had to twist and turn to absorb the energy.

The bottom line from these computer simulations is that both systems are safe for a single-story home in this specific seismic zone. The brick house wins on stiffness and staying put, while the steel house wins on being light and reducing the overall force of the earthquake. The study explicitly notes that it did not test how fast these houses can be built or how much they cost, so those famous claims about steel framing being cheaper or faster are not part of this specific finding. Within the digital world of this study, both dancers survived the music, proving that a lightweight steel home is a technically viable alternative to traditional brick, provided it is designed to handle its own unique style of swaying.

Technical Summary: Comparative Numerical Evaluation of Steel Framing vs. Confined Masonry in Peru

Problem Statement
Peru's location within the Pacific Ring of Fire necessitates rigorous seismic safety standards for housing, particularly in high-density areas like Lima. While confined masonry remains the predominant construction system in the country, governed by the National Building Code (RNE), prefabricated Steel Framing systems (using cold-formed galvanized steel profiles) have emerged as a lightweight alternative. However, a systematic, quantitative comparison of the seismic behavior between these two specific systems under the exact parameters of Peru's E.030 Standard—specifically for single-family dwellings—has been identified as a methodological gap. This study addresses the need for evidence-based technical decision-making by numerically evaluating how Steel Framing performs relative to confined masonry in a seismic zone, without relying on physical prototypes.

Methodology
The research employed a quantitative, non-experimental, cross-sectional, descriptive-comparative design. The study utilized computational simulation via ETABS 22 software, automated through the Python COM API, to model two three-dimensional structural prototypes with identical geometric dimensions (6.00 m × 4.00 m × 2.40 m) and site conditions (Type S2 soil in Lima, Seismic Zone 3).

Models:
- Confined Masonry: Featured 15×15 cm reinforced concrete columns ( $f'_c$ = 175 kgf/cm²) and load-bearing walls ( $f'_m$ = 65 kgf/cm²).
- Steel Framing: Utilized ASTM A446 Gr.C cold-formed steel profiles (C100×50×1.5 mm studs and U100×40×0.9 mm tracks) spaced at 0.60 m.
Analysis: Both models were subjected to modal analysis (12 modes) and CQC spectral analysis in accordance with E.030-2018. Key performance indicators included fundamental periods ( $T_1$ ), interstory drifts ( $\Delta/H$ ), base shear ( $V$ ), and internal forces (axial, shear, and bending moments).
Compliance: Results were verified against the E.030 limit for interstory drift ( $\leq 0.005$ ) and the 90% cumulative participating mass requirement. Internal forces were evaluated using LRFD (AISC 360-16) for Steel Framing and ultimate strength methods (E.060) for masonry.

Key Results
The numerical analysis yielded the following comparative findings:

Rigidity and Periods: Confined masonry demonstrated significantly higher lateral rigidity, with a fundamental period ( $T_1$ ) of 0.150 s compared to 0.280 s for the Steel Framing system (an 86.7% difference). Both periods fell below the corner period ( $T_p$ = 0.60 s) of the design spectrum, avoiding the zone of maximum spectral amplification.
Interstory Drifts: Both systems complied with the E.030 drift limit of 0.005.
- Confined Masonry: Maximum drifts were 0.0031 (X-direction) and 0.0029 (Y-direction), representing 62% and 58% of the limit, respectively.
- Steel Framing: Maximum drifts were 0.0048 (X-direction) and 0.0046 (Y-direction), representing 96% and 92% of the limit. While compliant, Steel Framing operated with a notably smaller safety margin.
Base Shear: Confined masonry exhibited a 32.3% higher base shear (35.2 kN) than Steel Framing (26.6 kN). This reduction in seismic demand for Steel Framing is attributed to its lower structural mass and the higher reduction coefficient ( $R=8.0$ ) assigned to steel systems compared to masonry ( $R=3.0$ ).
Internal Forces: Due to the absence of load-bearing walls, Steel Framing studs experienced significantly higher internal forces compared to masonry columns:
- Axial forces: ~29% higher.
- Shear forces: ~74% higher.
- Bending moments: ~190% higher.

Key Contributions
The study provides a traceable, numerical dataset comparing two distinct construction systems under identical regulatory and geometric constraints. By utilizing the ETABS 22 Python COM API, the authors established a replicable protocol for generating comparative seismic performance data. The research fills a specific gap in the literature by directly contrasting Steel Framing and confined masonry within the context of the Peruvian E.030 Standard, offering quantitative evidence regarding drift control, modal periods, and force distribution for single-story dwellings.

Significance and Claims
The paper concludes that, within the specific scope of a single-story prototype on Type S2 soil in Lima, both systems are technically viable and satisfy the seismic safety criteria of the E.030 Standard.

Confined Masonry is characterized by greater rigidity and superior drift control, offering wider safety margins.
Steel Framing is characterized by lower structural mass and reduced base shear demand, validating its potential as a lightweight seismic-resistant alternative.

The authors explicitly state that the study is limited to linear-elastic analysis and does not evaluate nonlinear behavior, soil-structure interaction, or construction economics. Consequently, the paper asserts that while Steel Framing is a viable structural alternative for the analyzed conditions, claims regarding construction speed or cost-effectiveness—often cited in broader literature—were not evaluated and should not be inferred from these specific seismic results. The significance of the work lies in providing a rigorous, data-driven foundation for engineers to consider Steel Framing as a compliant option for single-family housing in Peru's seismic zones, provided the specific geometric and regulatory constraints are met.

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