Panel Zone Modeling Improves Earthquake Analysis Accuracy in Six-Story Steel Buildings
FORMOSA NEWS – Modeling the panel zone in beam-column connections has been shown to significantly influence the seismic response of mid-rise steel buildings. This finding comes from a study conducted by Indah Nur Afiah and Mentari Septanya Sitorus from State University of Makassar (Universitas Negeri Makassar), published in the International Journal of Applied and Advanced Multidisciplinary Research (IJAAMR) in 2026. The researchers investigated how the inclusion of panel zone modeling affects the behavior of a Special Moment-Resisting Frame (SMRF) steel structure when subjected to earthquake loading. Using a six-story steel building model, the study applied simulations based on Indonesia’s seismic design standard SNI 1726:2019 and the official design response spectrum for Padang City, West Sumatra. The findings are particularly relevant for Indonesia, which lies within the Pacific Ring of Fire, one of the most seismically active regions in the world. As a result, developing accurate and reliable earthquake-resistant building designs remains a critical priority, especially in high-risk cities such as Padang, located near an active subduction zone.
Why Panel Zones Matter
In steel structures, beam-column connections are among the most critical components during an earthquake. Within these connections lies an area known as the panel zone, which experiences combined shear forces and bending moments generated by the interaction between beams and columns. In many structural analyses, panel zones are often neglected and the connections are assumed to be perfectly rigid. However, deformation within the panel zone can influence the overall structural response during seismic events. According to Afiah and Sitorus, incorporating panel zone behavior into structural models provides a more realistic representation of how steel buildings actually perform during earthquakes compared to conventional rigid-connection assumptions.
Comparing Two Structural Models
The research team developed two numerical models of a six-story steel building measuring 12 meters by 20 meters with a total height of 21 meters. The first model excluded panel zone effects, while the second explicitly incorporated panel zone modeling at beam-column joints. All other parameters—including structural dimensions, materials, loading conditions, and analysis settings—were kept identical to ensure that any differences in structural response resulted solely from the presence of the panel zone. The seismic performance of both models was evaluated using Response Spectrum Analysis (RSA), a dynamic analysis method widely used in earthquake engineering because it captures structural behavior more accurately than equivalent static approaches.
Greater Structural Flexibility Observed
One of the study’s most significant findings is that panel zone modeling increases structural deformation. In the X-direction, lateral displacement increased by 12.72 percent to 20.31 percent compared with the model that did not include panel zones. The largest increase occurred at the roof level. Similarly, inter-story drift, which measures relative movement between adjacent floors, also increased. The maximum increase reached 29.23 percent at the roof deck. These results indicate that panel zones introduce additional flexibility into the structural system because deformation occurs within the beam-column connection region. Despite the increased deformation, all displacement and drift values remained within the allowable limits specified by SNI 1726:2019, confirming that both structural models satisfied earthquake performance requirements.
Reduced Structural Stiffness
The study also revealed that panel zone modeling reduces the overall stiffness of the building. In the X-direction, story stiffness decreased by 12.02 percent to 31.30 percent, with the largest reduction occurring on the sixth floor. This decrease reflects the influence of connection deformation on the building’s ability to resist lateral movement. However, the effect on story shear, which represents the distribution of seismic forces throughout the structure, was relatively small. Differences between the two models ranged from only 0.13 percent to 1.35 percent. These findings suggest that panel zones primarily affect deformation and flexibility rather than significantly altering the distribution of seismic forces within the structure.
Building Stability Remains Within Safe Limits
The researchers also evaluated the P-Delta effect, a secondary structural effect caused by the interaction between gravity loads and lateral displacements during seismic events. Results showed that the model incorporating panel zones produced higher stability coefficients than the model without them. The largest increase reached 31.25 percent at the roof level. Nevertheless, all calculated stability coefficients remained well below the maximum limits permitted by Indonesian seismic regulations. This means that although panel zones increase deformation and flexibility, both structural models remained stable and safe under the design earthquake conditions.
More Realistic Earthquake-Resistant Design
The study demonstrates that including panel zone modeling provides a more realistic understanding of how steel moment-resisting frames behave during earthquakes. According to Indah Nur Afiah and Mentari Septanya Sitorus of the State University of Makassar, engineers should consider panel zone effects when analyzing earthquake-resistant steel structures because they significantly influence lateral deformation, structural stiffness, and overall seismic behavior. The findings may help structural engineers, consultants, researchers, and policymakers improve the accuracy of seismic design practices for steel buildings in Indonesia and other earthquake-prone regions. The authors also recommend future studies using advanced nonlinear analysis methods, such as Nonlinear Time History Analysis (NLTHA), as well as experimental validation to gain a deeper understanding of beam-column connection behavior under severe seismic loading.
Author Profiles
Indah Nur Afiah, S.T., M.T. Lecturer and researcher at the State University of Makassar. Her expertise includes structural engineering, seismic analysis, building performance evaluation, and earthquake-resistant design.
Mentari Septanya Sitorus, S.T. Researcher at the State University of Makassar whose work focuses on steel structures, earthquake engineering, and structural modeling.
Research Source
Title: Seismic Response of Mid-Rise Steel SMRF with Panel Zone Modeling
Authors: Indah Nur Afiah, Mentari Septanya Sitorus
Journal: International Journal of Applied and Advanced Multidisciplinary Research (IJAAMR)
Volume and Issue: Vol. 4, No. 5
Year: 2026
Pages: 283–300
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