Earthquake Resistance Tips and Tricks you need to know

07 Sketches
Jun 19
10 min read

Updated: Jun 30

Introduction

Designing structures in earthquake-prone areas demands in-depth understanding of seismic forces and how buildings can resist them. Earthquake-resistant design is a crucial aspect of structural engineering that aims to minimize damage and preserve life during seismic events. By addressing vulnerabilities in form, continuity, and material response, architects and engineers can create safer built environments. Let's break down key points you should know while constructing a building in seismic design.

Starting on the top left, we see what's called a soft story this is when the ground floor is much weaker than the upper floors, often because it's used as parking or has large openings with fewer walls. In an earthquake, this weak base can't hold up the weight above it, and it collapses. Now look directly below that: the strong base. Here, the ground floor is reinforced and enclosed, making it much sturdier. This solid base helps support the entire building when the ground shakes.

Next, the middle set of diagrams is about plane continuity. In the top middle, you’ll see a broken red line going down a building that represents plane discontinuity. This happens when columns or walls don’t line up from floor to floor, creating structural gaps. These gaps are risky because they break the natural flow of force through the building. Below that is the corrected version ,where everything lines up perfectly. That unbroken red arrow shows that the building has a clear and strong load path, which is key for safely carrying seismic forces downward.

Now, to the right side of the image, it’s all about shear walls these are thick walls designed to take on horizontal forces during a quake. The top right shows shear walls offset, meaning the walls are not placed directly on top of each other across the floors. This misalignment weakens the structure. But look below that and you’ll see the safer approach shear walls line up. When these walls are vertically aligned, they create a continuous, strong barrier that can resist earthquake forces much better.

The top row, which shows common structural flaws that make buildings highly vulnerable during earthquakes. First, In the weak lower levels here, the ground floor has been under designed, likely with minimal reinforcement or too many open spaces. When an earthquake hits, this level becomes the most likely point of failure, potentially causing the whole building to collapse from the bottom up.

Moving to the middle top image, we see discontinued vertical elements. This means that the building’s structural system like columns or walls doesn’t run in one continuous line from top to bottom. This disrupts the flow of forces and introduces weak spots where the building could easily buckle. On the top right is another serious issue: weak columns. Columns are the vertical spine of any structure, and if they aren’t designed to take on lateral seismic loads, the structure may sway excessively or collapse under pressure.

Now, the bottom row showcases the right way to approach these issues. On the bottom left, the strong lower levels image shows a solid, well-supported ground floor likely reinforced with bracing or heavier framing that can bear both vertical and lateral loads safely. Next to that is the symmetrical skeleton design. This is especially important when the structural system is symmetrical, the building behaves more predictably under seismic forces as asymmetry can lead to torsional twisting during an earthquake, which is dangerous.

Finally, the bottom right image highlights strong columns. These columns are not only thick but also well-integrated into the overall frame, offering both vertical support and lateral resistance. When columns are properly detailed and proportioned, they help absorb seismic energy and prevent progressive collapse.

Solutions for Earthquake resistant Structures :

Let's see how we can use base isolators for earthquake resistance.

In the top-left part of the image, we see a conventional building before an earthquake. It is directly anchored to the ground with no flexibility or buffer. After the earthquake hits, shown in the top-right, the entire structure tilts dangerously. Cracks appear in the walls, and the frame becomes unstable due to the direct transmission of seismic forces from the ground into the structure. This is a common failure scenario in buildings not equipped to absorb ground movements.

The bottom part of the image presents a more resilient alternative. It introduces base isolators placed between the building and its foundation. These isolators act like flexible pads or bearings that allow the building to sway gently during an earthquake, without damaging the structure above. In the bottom-left illustration, the base mass and isolator are clearly shown, separating the structure from the ground. In the bottom-right image, during an earthquake, the ground and base isolators move laterally, but the building itself remains upright and undamaged. This shows how isolators reduce the force transferred to the building and prevent structural collapse.

This principle is especially useful in hospitals, emergency centers, and high-rise buildings in seismic zones. It ensures the safety of occupants and maintains the building's integrity even after strong earthquakes.

Image a: This shows a building fixed directly to its foundation. When an earthquake occurs, the ground shakes, and since the structure is rigidly attached, the entire movement transfers upward. This results in the building tilting and undergoing large lateral displacements, which can cause cracks, internal damage, or even collapse.
Image b: This introduces base isolators placed between the building and the foundation. These isolators act like flexible bearings that can move independently from the building. When seismic motion occurs, the isolators absorb and decouple most of the ground movement.
Image c: Here we see the isolators in action. The red arrows indicate horizontal ground motion. Rather than transferring all this motion to the structure, the isolators allow the building to remain upright with minimal sway. The isolators deform instead, absorbing and dispersing the seismic energy safely.

Image a: Again, a traditional building rests directly on the ground. When the earthquake strikes, the entire ground movement is passed on to the structure, causing it to lean or sway dangerously. This results in large internal forces and potentially severe structural damage.
Image b: Here, the building is placed on frictionless rollers. While this setup removes force transmission to the structure and keeps it still, it is unrealistic for practical construction since there's no control over the movement. It helps to show that decoupling can reduce motion, but frictionless rollers lack damping and centering ability.
Image c: This is the practical and most effective solution a base-isolated building with Lead Rubber Bearings (LRB). These isolators allow the foundation to move freely with the earthquake, while the structure above moves only slightly. The isolators absorb the energy and limit how much of it travels upward. This results in a small force being induced in the building and minimal structural deformation.

Case Study: Sabiha Gokcen Airport Terminal, Istanbul, Turkey

Located on the Anatolian side of Istanbul, Sabiha Gokcen International Airport sits near the active North Anatolian Fault, exposing it to major seismic risk. Recognizing this, authorities and architects opted for an advanced seismic strategy during the new terminal's design and construction between 2008 and 2009.

Seismic design requirements: A seismic base isolation system to ensure effective damping

The Sabiha Gokcen International Airport offers a total area of more than 320 000 square meters and is comprised of an integrated domestic and international terminal building, a hotel, a new VIP terminal, and various other airport facilities. Its location in a seismic hazard zone determined the design of the building's structure. The main requirements included special measures to ensure safety in case of an earthquake.

According to the client’s requirements, two performance levels were defined for seismic analysis of the terminal building. These performance levels are as follows:1. The building was designed for Operational Level. i.e. no structural and no non-structural damage for an earthquake hazard with a uniform 10% probability of exceedance in 50 years, which is equivalent to a hazard with a return period of 475 years. This earthquake hazard is commonly known as Design Basis Earthquake (DBE) or design earthquake in practice.2. The building was designed for Structural Immediate Occupancy for an earthquake hazard with a uniform 2% probability of exceedance in 50 years, which is equivalent to a hazard with a return period of 2475 years.

This earthquake hazard is known as Maximum Considered Earthquake (MCE). The design of a standard, fixed-based structure that can comply with the stringent seismic performance objectives listed above would be uneconomical and infeasible. Therefore, it was decided to implement a base isolation system. A seismic base isolation system with energy dissipation capabilities enables shifting/elongation of the fundamental periods of structure and provides a significant increase in the effective damping. These two key features provide a significant reduction in the seismic design forces and inter-storey drifts of the superstructure; hence, reducing the risk of structural and non-structural earthquake damage.

Triple friction pendulum devices were used to build the world’s largest seismically isolated building. There are 300 triple-friction pendulum isolators that are distributed over the entire plan. Note that the triple-friction pendulum bearings, with a theoretical period of 3 seconds and displacement limit of 345 mm, were selected on the basis of performance and cost. The effective damping provided by the isolators is 38% and 30% at DBE and MCE events, respectively.

The structural system: Steel as the main protagonist

The new SGIA Terminal building is a steel structure with a plan dimension of 160 m by 272 m. The total building height is approximately 32.5 m. The building consists of four storeys above and a basement floor below the isolation plane. Typical floor heights are 6 m at the ground floor and 5 m at the upper levels. The gravity system of the superstructure is composed of concrete filled steel decks, composite steel beams, and composite steel columns. The superstructure resists lateral loads by a system of steel moment frames through rigid horizontal diaphragms.

The clear span length supported by the columns is 16 m in both directions. All structural members, such as columns and beams, are built-up members. Plates were cut in appropriate shapes and were connected via welding in order to constitute the required structural sections. Floor rib beams are made of grade S235 steel plates and columns and main beams are made of grade S355 steel plates. Rib beam layout orientations are changed in every main cell (16m x 16 m), so that all the main beams are loaded with the same gravity loads. The framing for the stairs and elevators below the isolation plane is suspended from and braced by the isolated super structure above.

The concrete compressive strength is 35 Mpa for composite columns.The roof system consists of light steel space purlin systems running longitudinally and located at every 8 m and braced in the transverse direction. The purlin has a parabolic curve form with a depth of 12 m and 6 m placed evenly next to each other. They are pin-supported by the top of the columns at every 32 m and 48 m. Purlins consist of pipe members which are in grade S355.

Unbalanced snow drift load was taken into consideration in the analysis due to the shape of the roof.In total, 18 600 tonnes of structural steel was used for the construction of the SGIA's new terminal building. ArcelorMittal Distribution Solutions - Rozak was the main steel supplier for this project providing the majority of steel beams and plates.

Source: https://constructalia.arcelormittal.com/

Earthquake Resistance in Load bearing structures

In earthquake-prone regions, ensuring the stability of load-bearing structures is crucial to avoid catastrophic damage. These types of buildings rely on walls to carry structural loads, making them more vulnerable to collapse if not carefully designed. However, by incorporating basic earthquake-resistant techniques into masonry construction, we can significantly reduce the risk. I have tried to explain this concept in a simple, visual manner showing not only what can go wrong, but also how it can be corrected with thoughtful detailing.

In the top part of the image, we see a common but unsafe condition. The structure is built entirely from unreinforced masonry with large, closely placed openings. This layout weakens the integrity of the walls, especially during lateral shaking. As shown in the image on the right, an earthquake has caused part of the wall to collapse completely, endangering the person inside. There are no vertical or horizontal reinforcements to bind the structure together, making it brittle and extremely risky during a seismic event.

Now look at the bottom half of the image, which shows a safer, earthquake-resistant version of the same structure. Here, the corners and wall junctions include reinforced concrete columns, which strengthen the wall and prevent it from cracking or detaching. A continuous concrete band is also provided at the lintel level to tie the entire structure horizontally and resist shear movement. These bands act like a belt around the building, holding it together during tremors.

Another important detail shown here is the spacing of openings. When windows and doors are placed too close together, they weaken the wall segment in between. The image suggests maintaining a minimum distance between openings, ideally at least half the height of the opening (H/2), and avoiding door-window combinations placed too close to corners.

Case study: 314 Houses in Bhuj - Bhimrao Nagar, Ramdev Nagar & GIDC Resettlement

Following the devastating 2001 earthquake in Gujarat, which caused widespread damage across Kutch, the need for resilient and community-focused housing became urgent. This project involved the rehabilitation of three settlements Bhimrao Nagar, Ramdev Nagar, and GIDC through the construction of 314 houses designed to resist future seismic activity while maintaining affordability and cultural relevance.

Brinda Somaya’s design approach was rooted in social sustainability, seismic safety, and local materials. Each housing unit was planned as a low-rise, load-bearing masonry structure, with carefully integrated earthquake-resistant elements. The site layout respected pre-existing social patterns and open spaces, fostering a sense of community among displaced families.

Earthquake-Resistant Features

Confined Masonry Walls: The houses were built using brick masonry confined with reinforced concrete (RC) bands at the plinth, lintel, and roof levels, which tied the walls together and prevented separation during lateral ground movements.
Vertical Reinforcement: RC vertical elements (at wall junctions and corners) were provided to strengthen structural continuity, acting like columns without changing the wall-dominant character of the house.
Symmetrical Plan Forms: The house designs avoided plan irregularities and placed openings away from wall edges. This minimized stress concentrations and improved the seismic response.
Lightweight Roofing: Roofing systems were kept lightweight to reduce the seismic mass and further limit top-heaviness, a key cause of collapse in poorly designed homes.

The project became a model for post-disaster reconstruction in India. The houses performed well in subsequent tremors and are still occupied today. This case illustrates how simple, low-tech seismic strategies, when thoughtfully applied, can offer lasting resilience without relying on expensive, high-rise solutions.

Thanks for reading!