Research

Research Interests

The research interests of our groups are currently focusing on the following thrust areas:
  • Development of Innovative Resilient Bridge Systems for Accelerated Construction and Superior Performance against Multiple Hazards
  • Integration of Advanced Materials in Structural Design
  • Performance-based Seismic Design and Life-cycle Assessment of Bridges
  • Mechanics-based Structural Modeling and Numerical Solution Methods (Emphasis on Softening/Deteriorating Systems)
  • Multi-objective Structural Design for Energy Harvesting and Vibration Mitigation
Our research endeavors include both analytical/computational and experimental studies conducted in the Structures and Materials Testing Laboratory (SMTL) at CU-Boulder.

Research Projects

Current and past research topics include:
VII.   Development of Seismic Resilient Bridges with Substructure Post-Tensioned Columns incorporating Flexible End Segments and Replaceable Energy Dissipating (ED) Links
This research, which is conducted by Mr. Mohammad Nikoukalam under the guidance of Prof. Sideris, aims at developing segmental bridge columns with flexible end joints and energy dissipating links. The flexible joints will allow the columns to accomodate large lateral deformations without damage. The ED links will provide hysteretic energy dissipation to limit the displacement demands. Flexible end joint materials that are currently being explored include various types of polyurethanes. The ED links will be external and replaceable. 

VI.   Design of Structures for Energy Harvesting and Vibration Mitigation
This research, which is conducted by Mr. Gregory Conroy under the guidance of Prof. Sideris, aims at developing structural systems that can provide large-scale energy harvesting under service loads (e.g., wind loads) and vibration mitigation under extreme loads (e.g., earthquake loads) through the use of energy harvesting viscous elements (exhibiting similar response to passive viscous dampers). Although large damping ratios are required for vibration mitigation under extreme loads, small damping ratios maintain low vibrations over longer periods of time under service loads; thereby, maximizing energy harvesting. To address these conflicting requirements in terms of the provided damping, this research aims at developing optimal control algorithms to vary the properties of energy harvesters so that energy harvesting is maximized without violating peak deformation requirements under service conditions and extreme events. Moreover, holistic design approaches, accounting for inter-dependencies between the structure and the harvesters

V.  Hybrid Sliding-Rocking  Post-tensioned Segmental Bridges
V-5. Development of Nonlinear Analysis Models for HSR Bridges
This research, which is conducted by Mr. Mohammad Salehi under the guidance of Prof. Sideris, focuses on the development of modeling strategies for HSR bridges. Particular emphasis is given at developing element formulations capable of capturing the sliding-rocking response of the segmental column joints. 

V-4. Design of Hybrid Sliding-Rocking Bridges using the Capacity Spectrum Method
This research, which is conducted by Mr. Sreenivas Madhusudhanan under the guidance of Prof. Sideris, aims at developing a strategy for the design of Hybrid Sliding-Rocking (HSR) Segmental Bridges using the Capacity Spectrum MethodRead more...

V-3. Assessing the Effect of Premature Tendon Fracture on the Response of Bridges with Rocking Columns
Recent research has shown that the ductility capacity and self-centering capabilities of columns with unbonded post-tensioning can be severely reduced due to the premature fracture of the tendons at the location of their anchorage hardware resulting from large stress concentrations. This research, which is conducted by Mr. Brandon Bowman under the guidance of Prof. Sideris, aims at providing a comprehensive qualitative and quantitative assessment of the the effect of premature tendon fracture on the seismic performance of bridges with rocking columns

V-2. Analysis of HSR Columns under Truck Collision
This research, which is conducted by Mr. Alexander Sutherland under the guidance of Prof. Sideris, aims at investigating the effects of truck collision loads on HSR bridge columns. 

V-1.   Seismic Analysis and Design of Precast Concrete Segmental Bridges
This research, which was led by Dr. Petros Siderisintroduced the concept of HSR bridges. This research demonstrated the high potential potential HSR bridges in the framework of Accelerated Bridge Construction (ABC) techniques, for applications in moderate and high seismicity areas. Read more...

IV.  Analysis of Softening/Deteriorating Structural Systems
IV-2. Gradient Inelastic Flexibility-based Frame Element formulation
This research, which is conducted by Dr. Petros Sideris and Mr. Mohammad Salehi, introduces a new gradient inelastic (GI) beam theory and develops a corresponding GI flexibility-based frame element formulation. The proposed formulation alleviates strain location and loss of objectivity. The proposed formulation results in a single system of nonlinear algebraic equations which can be solved using simple methods (e.g., Newton-Raphson iterations) avoiding the complicated nested loop solution formats, which are currently used in various applications. 

IV-1. Path-following Algorithms for Quasi-static Analysis of Softening Structures
This research, conducted by Dr. Petros Siderisfocuses on the development of path-following predictor-corrector methods to trace equilibrium paths (e.g., pushover curves) of deteriorating structures under force loading. Read more...

III.   Performance of Reinforced Concrete (RC) Columns with Partial Debonding of the Longitudinal Reinforcement
This research, which is conducted by Mr. Mohammad Nikoukalam under the guidance of Prof. Sideris, will assess the performance of  RC columns with partially debonded longitudinal rebar in the vicinity of the plastic hinge. Assessment will be performed through finite element analyses and large-scale quasi-static cyclic testing of RC columns. 

II. Seismic Behavior of Palletized Merchandise in Steel Storage Racks
This research, led by Dr. Petros Siderisinvestigated the seismic performance of palletized merchandise in steel storage racks and evaluated the concept of slightly inclined shelving as a means of mitigating the seismically induced content shedding. Read more...

I. Dynamics and Control of Electromagnetically Actuated Harmonic Drives 
This research, led by Dr. Petros Siderisfocuses on the modeling of the dynamic behavior of the flexible spline of electromagnetically actuated harmonic drives as well as the development of control laws able to achieve target operation performanceRead more...