fischer and Purdue University Develop Earthquake Retrofitting Solution Through Full-Scale Tests

The earth is constantly in motion as it rotates, orbits the sun and experiences ongoing activity beneath its surface. Around 500,000 earthquakes are registered globally every year, according to the US Geological Survey (USGS). Areas including the Pacific Ring of Fire, the Himalayas, the Mediterranean, Central America and the Caribbean face heightened risks due to frequent tectonic movement.

Human activities, including oil and gas extraction, fracking, geothermal drilling and the construction of large reservoirs, can also trigger seismic activity. In earthquake-prone regions, structural designers and engineers must ensure not only that buildings have sufficient load-bearing capacity but also that non-load-bearing components, including pipes, cables, suspended ceilings, cable runs, air conditioning units and facades, do not fail or collapse.

However, many people living in seismic zones occupy existing buildings that were constructed before current earthquake-resistant standards were implemented. Such structures are often unable to safely withstand seismic loading, creating an urgent need for effective retrofitting methods.

To address this challenge, the fixing specialist fischer and Purdue University, one of its partner universities, conducted a large-scale research project focused on seismic structural reinforcement. An innovative retrofitting solution was verified through extensive full-scale tests on reinforced concrete structures.

The researchers examined the behaviour of beam-column joints, which are critical points in supporting structures. These connection areas experience particularly high stresses and significant forces caused by horizontal loading during earthquakes. “These node points in supporting structures are subjected to particularly high stresses and significant force caused by horizontal loading during an earthquake”, explains Dr Margaritis Tonidis, a former PhD Candidate at Purdue University and leading Project Engineer of the project.

Failure of these joints can result in the collapse of the entire structural system, making their reinforcement a key focus of earthquake retrofitting research.

The project successfully tested a reinforcement system consisting of bonded anchors and haunch elements for retrofitting beam-column joints. The solution used fischer injection mortar in combination with threaded rods.

The bonded anchor system showed minimal deformation under loading and was able to reliably absorb and transfer forces. This enabled the haunch retrofit solution to protect critical joints effectively during seismic stress, creating safe and controlled load-bearing behaviour during earthquake conditions.

The reinforcement system changes the force flow between beams and columns by redistributing loads from the joint area into adjacent structural elements. Defined failure mechanisms help prevent complete structural collapse.

“The injection mortar proved to be a highly reliable adhesive anchor for post-installed strengthening even under very high seismic demands and led to achieving ground breaking results during the tests”, emphasises Prof Akanshu Sharma, Associate Professor at Purdue University and former Endowed Professor at the Institute of Materials Science at the University of Stuttgart.

“We were able to demonstrate a significantly improved performance of the strengthened structure under seismic loading,” Prof Sharma said.

During comparative testing, the structural system without strengthening showed major damage in beam-column joints, while the structure reinforced with the fischer system demonstrated superior performance. The fischer bonded anchor system can also be installed while a building remains in use, without causing any major interruption, Prof Sharma added.

“The project was a fantastic and unique opportunity to review and test the results and concepts we gained in our previous research under realistic conditions,” emphasises Dr Erik Johannes Stehle, Head of Development FiXperience at fischer.

Dr Stehle said the project again demonstrated that the effectiveness of seismic reinforcement solutions depends heavily on anchorage performance. The bonded anchor system achieved strong results at both the structural level and within beam-column joints, showing high rigidity and low deformation under high-load conditions.

The research collaboration between fischer and Purdue University highlights the role of international partnerships in developing new engineering solutions. Dr Erik Stehle emphasised, “We need international research collaboration. By communicating with each other, we gain inspiration, ideas and impetus for new innovations while strengthening our position as a global innovator.”

Prof Sharma also highlighted the importance of cooperation between scientific institutions and businesses. “At Purdue University, we’re proud to have already conducted several groundbreaking research projects with the fischer Group of Companies, including the world’s first seismic test using full-scale structures with a post-installed reinforcement solution for joints with haunch elements.”

The validated research findings are now being translated into practical applications for existing buildings. The results demonstrate that realistic and affordable approaches can improve the resilience of older structures, helping protect infrastructure and save lives during earthquakes.

Commenting on the significance of the innovation for India, Mayank Kalra, Managing Director, fischer India, said, “India is among the fastest-growing infrastructure markets in the world and has several regions that are vulnerable to seismic activity. While modern construction follows advanced earthquake-resistant design standards, strengthening existing buildings remains equally important.”

“India is among the fastest-growing infrastructure markets in the world and has several regions that are vulnerable to seismic activity. While modern construction follows advanced earthquake-resistant design standards, strengthening existing buildings remains equally important. This validated seismic retrofitting solution demonstrates how innovative fixing technologies can enhance structural safety, extend the life of existing infrastructure and contribute to more resilient cities,” he added.

“At fischer India, we are committed to bringing globally proven engineering solutions to the Indian market and supporting safer, more sustainable infrastructure development,” Mayank Kalra said.