Surreal illustration of a resilient infilled frame structure during an earthquake.

Building Bridges, Not Walls: How Infilled Frames Can Revolutionize Earthquake-Resistant Design

Samir D’Costa in Tech & Innovation June 2025 • 4 min read.

"Discover the potential of infilled frame structures (IFS) and a groundbreaking 3D macro-element model that's changing how we approach seismic safety in buildings."

In many cities, a common sight is buildings constructed with frames of concrete or steel, filled in with walls made of brick or masonry. This method, known as infilled frame structure (IFS), blends structural support with architectural design. While these infill walls seem like simple space fillers, they play a significant role in how the building responds to stress, especially during earthquakes.

Traditionally, engineers often overlook the contribution of these masonry infills when analyzing a building's structural integrity. This oversight can lead to critical inaccuracies in predicting how the building will behave under seismic conditions. Ignoring the infills means missing a key component that affects the building's stiffness, strength, and ability to absorb energy.

But now, a groundbreaking approach is changing this perspective. Researchers have developed a three-dimensional discrete element method, a sophisticated model that simulates the complex interactions within IFS. This model considers both in-plane and out-of-plane behaviors, offering a more realistic and reliable assessment of structural performance. Let's delve into how this innovative model works and why it could revolutionize earthquake-resistant design.

Unveiling the 3D Macro-Element Model: A Game Changer for Structural Analysis

Surreal illustration of a resilient infilled frame structure during an earthquake.

The heart of this innovation lies in its ability to mimic real-world conditions with remarkable precision. The model treats the infill wall as a collection of interconnected elements, each responding individually to stress. This allows engineers to observe how forces distribute throughout the wall and how the wall interacts with the surrounding frame.

Unlike simpler models, this 3D approach captures both in-plane and out-of-plane behaviors. In-plane behavior refers to how the wall reacts to forces applied within its plane, like shear stresses from an earthquake. Out-of-plane behavior, on the other hand, describes how the wall responds to forces pushing it outward, potentially causing it to collapse. By simulating both, the model provides a holistic view of structural performance.

The key benefits of the 3D macro-element model include:

Realistic Simulation: Accurately replicates the complex interactions between the infill and the frame.
Comprehensive Analysis: Considers both in-plane and out-of-plane behaviors for a complete picture.
Improved Accuracy: Provides more reliable predictions of structural response under seismic loads.
Optimized Design: Enables engineers to design safer and more resilient buildings.

The model's accuracy has been validated through rigorous experimental comparisons. Researchers have tested it against real-world data, demonstrating its ability to predict the behavior of infilled frames under various loading conditions. This validation is crucial because it provides confidence in the model's reliability and its potential for practical application.

Building a Safer Future: The Promise of Infilled Frame Structures

The development of this 3D macro-element model represents a significant step forward in earthquake-resistant design. By providing a more accurate and comprehensive understanding of infilled frame structures, it empowers engineers to create safer, more resilient buildings. As we face increasing seismic risks in densely populated areas, innovations like this are essential for protecting lives and infrastructure. The future of construction lies in embracing these advanced tools and methodologies to build a world where buildings can withstand the forces of nature.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.engstruct.2018.08.022, Alternate LINK

Title: A 3D Discrete Macro-Element For Modelling The Out-Of-Plane Behaviour Of Infilled Frame Structures

Subject: Civil and Structural Engineering

Journal: Engineering Structures

Publisher: Elsevier BV

Authors: B. Pantò, I. Caliò, P.B. Lourenço

Published: 2018-11-01

Everything You Need To Know

What are infilled frame structures (IFS), and why are they important in building design?

Infilled frame structures (IFS) are buildings where frames made of concrete or steel are filled with walls, often constructed of brick or masonry. These infill walls significantly affect how a building responds to stress, particularly during earthquakes. They contribute to the building's stiffness, strength, and ability to absorb energy, making them crucial components in seismic design.

How does the 3D macro-element model improve upon traditional methods of analyzing infilled frame structures (IFS)?

Traditional methods often overlook the contribution of the masonry infills, leading to inaccurate predictions of a building's behavior during earthquakes. The 3D macro-element model, however, offers a more realistic and reliable assessment by simulating complex interactions within the IFS. This model considers both in-plane and out-of-plane behaviors, providing a comprehensive understanding of how the structure performs under seismic loads, unlike simpler models.

What are the key benefits of using the 3D macro-element model in the context of earthquake-resistant design?

The key benefits include realistic simulation of interactions between the infill and frame, comprehensive analysis by considering both in-plane and out-of-plane behaviors, improved accuracy in predicting structural responses under seismic loads, and the ability to optimize building designs for enhanced safety and resilience. This holistic approach leads to more informed engineering decisions.

Can you explain the difference between in-plane and out-of-plane behaviors of infilled frame structures (IFS) and why both are important?

In-plane behavior refers to how the infill wall reacts to forces within its plane, such as shear stresses from an earthquake. Out-of-plane behavior describes how the wall responds to forces pushing it outward, potentially leading to collapse. The 3D macro-element model considers both to provide a complete picture of structural performance. Understanding both is critical because an earthquake can induce forces in multiple directions, and ignoring either aspect could lead to significant structural weaknesses.

How does the validation of the 3D macro-element model with real-world data impact its practical application in the construction industry?

The validation of the 3D macro-element model through experimental comparisons with real-world data is crucial. It demonstrates the model's accuracy in predicting the behavior of infilled frames under various loading conditions. This validation builds confidence in its reliability and encourages its adoption in the construction industry. Engineers can use the model with greater certainty, leading to the design of safer and more resilient buildings that can better withstand seismic events.