Strengthening Risky Structures in Disaster-Prone Areas

The topic of "Strengthening Risky Structures in Disaster-Prone Areas" is often associated with construction sites in Turkey, a country located in an earthquake zone, where the first image that comes to mind when urban transformation is mentioned is that of massive construction machinery demolishing buildings and erecting new reinforced concrete blocks from scratch. This "demolish and rebuild" model, ingrained in our minds over the years, has been accepted as the only and absolute way to ensure earthquake safety. However, developing structural engineering technologies, the global climate crisis, and economic realities offer us a much more sustainable, faster, and rational alternative: Structural Strengthening.

Demolishing and rebuilding every risky building is similar to the medical world where, instead of treating a diseased organ, it's about cutting it off. Just as advanced medical technologies prioritize healing the organ in situ, modern civil engineering aims to make buildings earthquake-resistant by rehabilitating their structural system without demolishing them. In areas at risk of disaster, protecting property rights, maintaining the sociological fabric, and preventing economic collapse can only be achieved by moving away from a wholesale demolition approach and adopting a "strengthening-focused" transformation paradigm.

This article analyzes, within an academic framework but in an understandable language that any citizen, even one unfamiliar with the subject, can consider as an alternative for their own living space, why and how risky structures in disaster-prone areas should be strengthened instead of demolished, the legal basis for this process, engineering methods, and economic and environmental advantages.

1. Legal Framework: How Does the Law View Empowerment?

Although Law No. 6306 on the Transformation of Areas Under Disaster Risk, considered the main constitution of urban transformation, may at first glance appear to be a text entirely focused on demolition, it actually contains a very clear legal avenue that paves the way for strengthening within itself.

Law No. 6306, Article 6/1 and Strengthening Requirement

The implementing regulations and relevant articles of the law provide a very clear exception to the obligation to demolish a building that has been definitively identified as a risky structure. According to the law, if it is determined that strengthening the risky building is technically feasible instead of demolishing it, and a decision is made to that effect, the demolition process of the building is stopped.

Legally, the following steps are mandatory for this:

• Technical Report: A detailed “Strengthening Project and Feasibility Report” demonstrating that strengthening the building is technically and structurally feasible must be prepared by a licensed engineering firm.

• Majority Decision: According to Article 19 of the Condominium Law (KMK), the owners of the condominium units must decide on strengthening the building with a four-fifths (4/5) majority. However, in some applications under Law No. 6306 and in judicial precedents, this ratio can be relaxed to a simple majority (51 percent) in situations where there is an urgent need for life safety.

• Permit Application: Following this joint decision, a "Strengthening Permit" must be obtained from the relevant municipality within the legal eviction periods. Once the permit is obtained, the demolition order issued by the municipality for that building becomes legally null and void.

2. Why Empowerment? Three Key Pillars

There are three massive structural reasons—economic, environmental, and social—behind choosing to reinforce buildings instead of demolishing and rebuilding them.

A. Economic Pillar: Cost Analysis and Resource Management

The cost of demolishing an earthquake-prone building and rebuilding it from scratch has reached astronomical levels, especially due to high inflation and increases in construction inputs (steel, cement, labor).

• Cost Ratio: According to international engineering standards and on-site feasibility studies, if the cost of reinforcing a building does not exceed 30 to 40 percent of the cost of constructing it from scratch , then the reinforcement process is highly economically viable.

• Threshold Value: If the cost of reinforcement exceeds 50% of the cost of reconstruction, then demolishing and rebuilding the building is considered rational. However, in the vast majority of the existing housing stock in Turkey, reinforcement costs remain well below this threshold, averaging around 25-35%. This means that the amount of money citizens have to pay out of pocket would be reduced by almost two-thirds.

B. Social and Psychological Column: Neighborhood Culture and the Right to Housing

Demolishing and rebuilding a building involves a grueling construction process that lasts at best 18 to 24 months. During this process, homeowners and tenants are forced to leave their neighborhoods, their children's schools, their familiar shops and neighbors, and disperse to other parts of the city. This leads to sociological traumas such as "urban displacement" and "gentrification.".

• Time Advantage: Strengthening projects are typically completed in as little as 4 to 8 months , depending on the building's condition and the chosen method . Some modern strengthening technologies (such as carbon fiber applications or the addition of external steel framing) allow residents to continue living in their homes without even needing to completely evacuate.

C. Environmental Pillar: Carbon Footprint and Waste Management

The construction industry is responsible for approximately 40% of carbon emissions and resource consumption worldwide. Every demolition means the generation of enormous amounts of concrete, iron, and plastic waste (rubble). The transportation, storage, and environmental damage caused by this waste constitute an ecological disaster.

• Sustainability: Strengthening an existing building while preserving it minimizes the production of new concrete and cement. Because the existing structural framework is maintained, the amount of carbon released into the environment is 60-70% less compared to a demolition and reconstruction scenario. Strengthening is, quite literally, a "green and environmentally friendly urban transformation" model.

3. Which Buildings Are Suitable for Strengthening?

Just as not every diseased organ can be saved, not every risky building can be reinforced. There are technical analyses that structural engineers conduct in both laboratory and field settings to determine whether a building is suitable for reinforcement.

Concrete Quality and Structural System Analysis

Core samples (concrete specimens) taken from the building must show concrete strength (resistance) above a certain minimum limit. For example, buildings with extremely low concrete strength, almost turning to sand when rubbed by hand (concrete quality C8 and below), and where the reinforcing steel has completely corroded and melted, are technically very difficult to reinforce and their cost may exceed that of rebuilding.

Soil Characteristics

The risk of liquefaction, landslides, or direct location on an active fault line of the ground on which the building sits is analyzed. Soil improvement methods (techniques such as pile driving and jet-grouting) can be used to stabilize the soil beneath the building, but in areas where the soil structure is entirely subsidence zones, reinforcing the building from above may be pointless.

Geometric Layout

The more regular and symmetrical the building's architectural design and structural system, the more successful the strengthening project will be. In buildings with excessively soft stories (where the ground floor lacks walls for commercial use) or heavy overhangs, these weaknesses can be addressed with a strengthening design.

4. Technical Steps of the Strengthening Process

Strengthening a building is not a routine renovation. It requires millimeter-precise calculations and a serious engineering discipline. The process proceeds chronologically in the following steps:

 

5. Main Strengthening Methods and Technologies

Modern civil engineering has developed various “treatment” methods to suit different budgets and building types in order to extend the lifespan of buildings and make them more earthquake-resistant.

A. Reinforced Concrete Jacketing (Column Cladding)

This is the most classic and traditional method. New steel reinforcement is woven around the building's existing weak columns, and then the columns are thickened by pouring high-strength special concrete.

• How it works? The column's load-bearing and bending capacity is increased many times over. Just like a broken arm is put in a cast, the column is covered with a concrete armor on the outside. This method is reliable, but it does lead to a slight loss of space in the interior of the building (in the apartments).

B. Carbon Fiber Reinforcement (CFRP – Carbon Fiber Reinforced Polymer)

Carbon fiber technology, used in the aerospace industry, has revolutionized the construction sector. Carbon fiber fabrics, which are many times lighter than steel but have approximately 10 times the tensile strength of steel, are actively used in strengthening buildings.

• How it works? Columns and beams are tightly wrapped with carbon fiber fabrics using special epoxy adhesives. This wrapping (bracing) prevents the concrete from expanding and cracking laterally. Its biggest advantage is that, because it's only a few millimeters thick, it doesn't cause any loss of space within the apartment, and its application is extremely fast, quiet, and clean.

C. Addition of New Reinforced Concrete Shear Walls

During an earthquake, buildings need rigid elements that limit lateral swaying (horizontal displacement). Thick reinforced concrete "shear walls" are constructed in specific openings or on the exterior of the building, extending continuously from the foundation to the roof.

• How it works? These new shear walls absorb the destructive horizontal energy of an earthquake directly, preventing load from being placed on weak columns. This limits the displacement of the building during an earthquake, ensuring it remains standing.

D. Seismic Isolators (Earthquake Isolation)

It is a cutting-edge technology used especially in strengthening historical buildings, hospitals, and luxury residential projects.

• How it works: Special rubber or steel seismic isolators are placed at the points where the building's foundation and supporting columns meet. During an earthquake, as the ground shakes, these isolators dampen the shaking and prevent the transfer of earthquake energy to the upper floors of the building. The building sways slightly, as if independent of the ground, and those inside don't even feel the earthquake. Applying this to existing buildings requires advanced engineering and a significant budget, but it is the ultimate safety solution.

6. Obstacles to Empowerment and Solutions

Despite being such an advantageous, economical, and safe method, why hasn't strengthening [building reinforcement] achieved the widespread adoption it deserves in urban transformation? There are several psychological, administrative, and legal obstacles hindering this.

The "Demolish and Rebuild" Habit of the Construction Industry

A large portion of contractors in the construction market are proficient in traditional concrete pouring and construction practices. Strengthening, however, requires expertise, precise engineering calculations, and specialized equipment. Contractors are imposing the "demolish, rebuild, and sell" model on citizens, which they perceive as less risky and yielding higher profit margins. To overcome this obstacle, it is essential for the government to incentivize and license firms with expertise in strengthening projects.

Financing and Credit Shortage

For many years, rental assistance and low-interest construction loans provided by the state for buildings demolished and rebuilt as part of urban transformation projects have treated strengthening projects like stepchildren. However, citizens undertaking strengthening projects should also be offered attractive long-term, low-interest "Strengthening Loans" and grant support, just like those for demolition and reconstruction. This would both reduce the financial burden on the state and enable the rapid rescue of many more buildings.

Disputes Between Apartment Owners

The four-fifths majority required by the Condominium Law is hindering reinforcement projects due to personal disputes within apartment buildings. The resistance of one or two apartment owners, such as "I won't pay" or "I want a new building," jeopardizes the safety of the entire building. To overcome this legal obstacle, the simple majority (51%), which is the general majority limit in urban transformation, must be applied fully and without flexibility to reinforcement projects as well.

Conclusion: Racing Against Time to Save Lives

Earthquakes test not the age or aesthetics of buildings, but the resistance of their structural systems under dynamic loads. A building doesn't necessarily have to be brand new, ultra-luxurious, and have a modern facade to be safe. A 40-year-old building, properly diagnosed, designed according to engineering standards, and reinforced with quality materials, is far safer than a 2-year-old building that is poorly constructed or uninspected.

In disaster-prone areas, time is our greatest enemy. We lack both the economic resources and the time to demolish and rebuild every single building to prepare our cities for the major earthquakes that lie ahead. Strengthening buildings is the most rational way to accelerate urban transformation, utilize our resources efficiently, and, most importantly, guarantee the safety of as many people as possible in the shortest time.

For the state, local governments, and citizens to move away from the "demolish and rebuild" dogma with a shared awareness, and to accept building reinforcement as the primary and most respected instrument of urban transformation, is the smartest way to build resilient, sustainable, and safe cities of the future. Demolishing buildings is easy; what is difficult but noble is preserving them and protecting the people within them.