Major Research Projects
Strengthening methods for pre-stressed concrete beams using FRP anchors and laminates
• Sponsors: NYSDOT, FHWA; PI: A. Stavridis
The goal has been to achieve a cost-effective, easily-constructible, and reliable alternative to the replacement of deteriorated bridges. The focal point of this study was a three-span 193-ft.-long deteriorated highway bridge located in upstate NY. Three 56-feet long bridge girders were repaired using a novel method, which utilizes CFRP anchors and laminates, and were subjected to load tests at the University at Buffalo to assess the performance of the repair. The test results have indicated considerable increase in the flexural capacity of the beams, making this repair method a viable solution for bridges with moderate to severe deteriorations. The dynamic properties of the highway bridge were also estimated using data obtained from ambient- and impulse-excitation measurements conducted at the bridge at various demolition stages. This data, combined with those obtained from the quasi-static tests on the bridge girders are being used to inform a numerical model of the bridge. The findings can be used for various objectives such as assessment of similar bridges, retrofit strategies, etc.
• Retrofit application timelapse
• Beam 1 capacity test | FRP laminate layers: 3 | Total FRP anchors: 14
• Beam 2 capacity test | FRP laminate layers: 2 | Total FRP anchors: 14
• Beam 3 capacity test | FRP laminate layers: 1 | Total FRP anchors: 14
Dynamic Nonlinear Testing of a 2-Story Building
• Sponsor: NSF; PIs: A. Stavridis, B. Moaveni
The building, located in El Centro, CA and constructed in the 1920s, had sustained damage during three major earthquakes by 1987 mainly in the first story and had been repaired and retrofitted in the late 1980s. During the 2010 Baja California earthquake, the second story infills and frames were severely damaged and the building was slated for demolition. During the testing period, four infill walls were removed at three stages introducing four levels of damage to the building. A series of forced vibration tests were performed on the structure to investigate its dynamic properties in the quasilinear and nonlinear ranges using a mass eccentric shaker at all damage states. The results are also used to validate a nonlinear model which implements a novel material law to model infills.
Test Structure Condition Prior to the Tests
Watch a report on the tests: Shake Test Demo
Eccentric Mass Shaker
Nonlinear Forced Vibration Tests
Force Drift Recorded During a Sine Step Test
Force vs. Drift vs. Forcing Frequency Recorded During a Sine Step Test
Dynamic Testing of a 10-Story Building
• Sponsor: NSF; PIs: A. Stavridis, B. Moaveni
The structure was a reinforced concrete building with a slab-column structural system and RC infill walls in the exterior bays which was constructed in 1914 in Utica, NY. Prior to the tests RC infill walls in the first, second, and fifth stories along the north, west, and south sides were removed prior to the tests to weaken the structure and facilitate the demolition. During the testing sequence, six RC walls were entirely removed from the second and third stories of the structure to simulate damage. A total of 87 forced vibration tests were performed using a mobile shaker. The accelerations along the vertical and horizontal directions at two corners of every story were recorded with 60 accelerometers. The results are used to evaluate the performance of the health monitoring methods in identifying and quantifying damage. A finite element model of the structure is also developed, validated, and used for several parametric studies.
Eccentric Mass Shaker
Wall Removal Order and Accelerometers Loaciotns
Condition Assessment of Damaged/Deteriorated Structures
• Sponsors: NSF, ATC, ESPE; PI: A. Stavridis
A total of 11 RC buildings, a school building, and two RC hospitals damaged after the 2017 Puebla earthquake in Mexico, 2015 Gorkha earthquake in Nepal, and 2016 Muise Earthquake in Ecuador, respectively, were the subject of vibration-based condition assessment. The goal in all cases was to identify the dynamic properties of the structures and validate a finite-element model which is then used in model updating to locate the damage. To this end, ambient vibrations were measured from all of the structures, and their modal properties were estimated through time- and frequency-domain system-Identification methods.
Development of a Material Law to Simulate Cyclic Behavior of Infilled Frames
• Sponsor: NSF; PI: A. Stavridis
The proposed law utilizes a recently proposed methodology that estimates the backbone curve describing the lateral force-vs.-displacement behavior of an infilled RC frame. Developed based on an extensive study of experimental data, the rule can simulate the combined cyclic behavior of the infill and the bounding frame accounting for the stiffness and strength degradation. The proposed model requires a few calibration parameters to predict the nonlinear behavior of infilled frames, values for which are also proposed. The material law is implemented in a nonlinear modeling framework and it is validated with the test results of tested infilled RC frames.
Schematic evolution of the material law
Material law performance assessment example:
Vibration-Based Condition Assessment Framework Development for Buildings
• Sponsor: NSF, University at Buffalo; PI: A. Stavridis
The goal of this study is to develop a data-driven framework which provides a reliable yet efficient assessment of buildings. The framework includes an interface which produces a variety of information regarding the structural properties of a building such as the frequency response function, mode shapes, and center of the rigidity, given the basic geometry of the building and ambient-level vibration measurements are available. Statistical learning algorithms are being implemented to automate the identification process. To this end, a database of buildings comprised of information about the structures and their modal properties is used to train the machine. The database includes information about 27 experimentally tested buildings as well as numerical building models with various geometry and structural systems. This tool will help engineers make retrofit and repair decisions based on the measured dynamic properties instead of solely relying on analytically estimated ones recommended by building codes.
Sample of a report summary including the required information for the vibration-based assessment of a building
Condition-assessment User Interface
Sample of the system-identification outputs: Power spectral density, 3D mode shape, floor deformations (including centers of rigidity)
Awards & honors
• O. H. Ammann Fellowship, American Society of Civil Engineers (ASCE) (2016)
• Chair’s Graduate Recognition Award, Department of Civil, Structural, and Environmental Engineering, University at Buffalo (2017)
• Best B.Sc. Thesis Award for Civil Engineering, Amirkabir University of Technology (2011)
• Travel support provided by Natural Hazards Engineering Research Infrastructure (NHERI) and EERI to participate in:
-SimCenter Programming Bootcamp, Berkeley, CA (2019)
-UC San Diego User Training Workshop, San Diego, CA (2019)
-Lehigh Researcher Workshop, Bethlehem, PA (2019)
-Wall of Wind Experimental Facility Workshop, Miami, FL (2019)
• Support provided by EERI to participate in:
-The EERI Annual Meeting, online (2021)
-The 11th National Conference on Earthquake Engineering, Los Angeles, CA (2018)
-The EERI Annual Meeting, Boston, MA (2015)
Publications
J1. Yousefianmoghadam S., Song M., Mohammadi M., Stavridis A., Moaveni B., Wood R. (2020). “Nonlinear Dynamic Testing of an RC-Infilled Building at Different Damage Levels.” Earthquake Engineering & Structural Dynamics, DOI: 10.1002/eqe.3271
J2. Yousefianmoghadam S., Behmanesh I., Stavridis A., Moaveni B., Nozari A., and Sacco A. (2018). “System Identification and Modeling of a Dynamically Tested and Gradually Damaged 10-Story Reinforced Concrete Building.” Earthquake Engineering & Structural Dynamics, DOI: 10.1002/eqe.2935
J3. Behmanesh I., Yousefianmoghadam S., Nozari A., Moaveni B., Stavridis A. (2018). “Uncertainty Quantification and Propagation in Dynamic Models Using Ambient Vibration Measurements, Application to a 10-story Building.” Mechanical Systems and Signal Processing, DOI: 10.1016/j.ymssp.2018.01.033
J4. Nozari A., Behmanesh I., Yousefianmoghadam S., Moaveni B., Stavridis A. (2017). “Effects of variability in ambient vibration data on model updating and damage identification of a 10-story building.” Engineering Structures, DOI: 10.1016/j.engstruct.2017.08.044
J5. Song M., Yousefianmoghadam S., Mohammadi M., Moaveni B., Stavridis A., Wood R. (2017). “An application of finite element model updating for damage assessment of a two-story reinforced concrete building and comparison with lidar.” Structural Health Monitoring, DOI: 10.1177/1475921717737970
J6. Ghofrani F., Yousefianmoghadam S., He Q., Stavridis A. (2020). “Ensemble Modeling of Rail Service Failures: An integrated Approach using Finite Element Modeling and Bayesian Analysis.” Computer-Aided Civil and Infrastructure Engineering (CACIE). (revised version addressing review comment submitted)
J7. Lan J., Stavridis A., Kim I., Diaz-Fanas G., Heintz J., Hernández L., Anzola E., Berkowitz R., Hussain S., Jalalian A., Garini E., Ktenidou O., Yousefianmoghadam S., et al. (2020). “ATC Mw7.1 Puebla-Morelos Earthquake Reconnaissance Observations Part II: Structural Observations and Instrumentation.” Earthquake Spectra. (revised version addressing review comments submitted)
J8. Tondi M., Bovo M., Yousefianmoghadam S., Vincenzi L., Stavridis S., Moaveni B. (2020). “Damage Assessment of Full-Scale Infilled Frames Using an Efficient Two-Steps Vibration Based Model Updating Procedure.” Structural Health Monitoring. (being revised/addressing reviewer comments)
J9. Bose S., Yousefianmoghadam S., Nozari A., Mohammadi M., Janadnejad F., Martindale G., Stavridis A., Moaveni B., Wood R., Gillins D. (2020). “Assessment and Nonlinear Modeling of a School Building at Sankhu Damaged by the 2015 Nepal Earthquake.” Earthquake Engineering and Structural Dynamics. (under review)
J10. Yousefianmoghadam S., Stavridis A. “Cyclic Behavior Simulation of Masonry Infilled RC Frames Using a Novel Material Law.” Engineering Structures. (to be submitted in March 2021)
J11. Yousefianmoghadam S., Stavridis A. “Machine-Learning-Driven Condition Assessment for buildings.” Structural Health Monitoring (to be submitted in May 2021)
J12. Yousefianmoghadam S., Stavridis A. “Improving Flexural Capacity and Stiffness of Prestressed RC Girders Using FRP overlays.” Journal of Bridge Engineering. (to be submitted in April 2021)
C1. Yousefianmoghadam S., Stavridis A. (2018). Material Law to Simulate the Nonlinear Cyclic Behavior of Infilled RC Frames. Proceedings of Eleventh U.S. National Conference on Earthquake Engineering, Los Angeles, CA
C2. Tondi M., Yousefianmoghadam S., Stavridis A., Moaveni B., Bovo M. (2019). Model Updating and Damage Assessment of a RC Structure Using an Iterative Eigenvalue Problem. IMAC XXXVI A Conference and Exposition on Structural Dynamics, Orlando, FL, DOI: 10.1007/978-3-319-74421-6_47
C3. Yousefianmoghadam S., Stavridis A., Moaveni B. (2017). Comparative Study on Modal Identification of a 10 Story RC Structure Using Free, Ambient and Forced Vibration Data. Proceedings of IMAC XXXV A Conference and Exposition on Structural Dynamics, Garden Grove, CA, DOI: doi.org/10.1007/978-3-319-54777-0_33
C4. Yousefianmoghadam S., Stavridis A. (2016). Nonlinear response of a dynamically tested two story infilled RC structure at different damage levels Proceedings of 2nd Huixian International Forum on Earthquake Engineering for Young Researchers HIFEEYR 2016, Beijing, China
C5. Yousefianmoghadam S., Behmanesh I., Stavridis A., Moaveni B., Nozari A. (2016). System Identification and Modeling of a 100-Year-Old RC Warehouse Dynamically Tested at Several Damage States. Proceedings of 1st International Conference on Natural Hazards and Infrastructure: Protection, Design, Rehabilitation ICONHIC 2016, Chania, Greece
C6. Behmanesh I., Yousefianmoghadam S., Nozari A., Moaveni B., Stavridis A. (2016). Effects of Prediction Error Bias on Model Calibration and Response Prediction of a 10-Story Building. Proceedings of IMAC XXXIV A Conference and Exposition on Structural Dynamics, Orlando, FL
C7. Yousefianmoghadam S., Song M., Stavridis A., Moaveni B. (2015). System Identification of a Two-Story Infilled RC Building in Different Damage States. Proceedings of 2nd ATC-SEI Conference on Improving the Seismic Performance of Existing Buildings and other Structures, San Francisco, CA
C8. Ramezanianpour A., Mahdikhani M., Yousefianmoghadam S., Nikravan M., Mousavi R. (2012). Mechanical Properties and Durability of Self Consolidating Mortars Containing Nano SI02. Proceedings of 3rd International Symposium on Ultra-High Performance Concrete, Kassel, Germany