Structural Engineering and Mechanics

Research Project Abstracts: 2005 - 2006

Modeling and Optimization of Civil Engineering Infrastructure
J.W. Baugh and E.D. Brill
Blue Ridge Analytics
12/04 to 12/05
In this project, computer software was developed to model and optimize civil engineering infrastructure problems using mathematical programming and heuristic search methods. The techniques were designed so that methods could be readily implemented to provide alternative solutions, which would meet given constraints on modeled objectives and which could be provided to users of the software.

Efficient Computational Methods for Accurate Simulation of Wave Propagation
M.N. Guddati
National Science Foundation
01/01 to 09/06
Wave propagation is encountered in countless problems of practical importance such as nondestructive evaluation, earthquake engineering, seismology and medical imaging. In spite of its immense importance and extensive research performed, the current approaches to modeling of wave phenomenon still suffer from several shortcomings related computational efficiency and accuracy. This project is aimed at devising new and efficient modeling techniques that would result in highly accurate solutions with relatively low computational cost. Most recent results from this research are related to dispersion reducing finite element methods and absorbing boundaries.

Remote Observation and Control of a Shake Table Experiment
Abhinav Gupta, V.C. Matzen, and M.A. Gabr
NC State University, DELTA/ IDEAS Grant
Fiscal Year 2003-04 to 2004-05
This project supports tasks that are needed in addition to those being conducted in the development of a prototype for remote observation and control of a shake table experiment under an NSF sponsored project. These tasks are needed to integrate the prototype with the University computing network for incorporation in distance education courses. The tasks need to be implemented in a manner that would maintain real-time safety as well as security features built into the prototype. While the tasks being undertaken are specific to the shake table experiment, the outcome of this work can be extended to other experiments either directly or with only minor modifications.

SST: Polymer Fiber and Waveguide Sensors for Performance-Based Assessment and Health Monitoring of Civil Infrastructure Systems
T. Hassan, M.J. Kowalsky, and K. Peters
National Science Foundation
08/04 to 07/07
The goal of the project is to develop polymer sensors for health monitoring of civil infrastructure systems. Of specific interest is to develop a sensor that can measure strains in excess of 6% under high strain rates. Although the sensors to be developed can be utilized under a variety of load conditions and structural materials, this research program will focus on application of the sensors to concrete and steel structures subjected to earthquakes loads. The research will develop a data acquisition system that can be utilized in health monitoring and techniques for bonding the polymer sensors to concrete structures.

A Multiscale Study of Ratcheting Failure Mechanisms in Austenitic and Ferritic Steel Welded Joints
T. Hassan and K.L. Murty
National Science Foundation
08/04 to 07/07
The goal of the project is to study multiscale failure mechanisms of austenitic and ferritic steel welded joints subjected to low-cycle fatigue loading. The progressive accumulation of strain with cycle known as ratcheting is believed to result in unexpected failures of defect-free joints. This project will perform low-cycle fatigue tests of welded joints and transmission and scanning electronic microscopy studies of dislocation substructures of the heat affected zone and base metals at various stages of fatigue life. Efforts will be made to develop a model for simulating ratcheting responses of welded joints using both macroscale and multiscale based constitutive models.

Calibration of Rutting Models for HMA Structural and Mix Design
R. Kim and M.N. Guddati
NCHRP 9-30A, Subcontract from Applied Research Associates, Inc.
11/05 to 10/08
The objective of this research effort is to recommend revisions to the HMA rut depth prediction model in the mechanistic-empirical pavement design guide and software developed in NCHRP Project 1-37A for consideration by the NCHRP Project 1-40 panel and the AASHTO Joint Task Force on Pavements. The recommended revisions will be based on the calibration and validation of distress models with measured materials properties and performance data from existing field and other full-scale pavement sections that incorporate modified as well as unmodified asphalt binders.

Development of Multi-axial VEPCD-FEP++ and its Extension to Indirect Tension Test
Y.R. Kim and M.N. Guddati
Federal Highway Administration
09/05 to 08/07
Over the past decade, the NCSU research team has been successful in developing HMA models that can accurately capture various critical phenomena such as microcrack induced damage, strain rate - temperature interdependence, and viscoplastic flow that is critical for high temperature modeling; the resulting model is termed the viscoelastoplastic continuum damage (VEPCD) model. The primary objectives of this research are: (1) to extend the VEPCD model to multiaxial state of stress; (2) to develop a three-dimensional finite element program with the multiaxial VEPCD model; and (3) to extend the principles used in the VEPCD modeling to the indirect tension mode.

Development of the Asphalt Pavement Performance Prediction Methodology Based on the Viscoelastoplastic Continuum Damage Theory
Y.R. Kim and M.N. Guddati
Korea Highway Corp.
10/04 to 12/06
The primary objectives of this research are: (1) standardization of test and analysis methods for the determination of viscoelastic properties and performance of asphalt mixtures; (2) development of the multiaxial viscoelastoplastic continuum damage (VEPCD) models using the indirect tension test and triaxial permanent deformation test; (3) development of the VEPCD finite element program (VEPCD-FEP++); (5) calibration of the VECPD-FEP++ using the data measured from the KHC Test Road pavements; (6) development of transfer functions for the 33 asphalt pavements in the Test Road; and (7) development of a user-friendly graphic interface for pre- and post-processing of the VEPCD-FEP++.

Characterization of ALF Mixtures Using the Viscoelastoplastic Continuum Damage Model
FHWA
Y.R. Kim and M.N. Guddati
08/03 to 08/05
The primary objectives of the proposed research are: (1) to verify the time-temperature superposition principle in damaged states for various asphalt mixtures used in the current ALF study; (2) to characterize the ALF mixtures using the viscoelastoplastic continuum damage model; and (3) to predict the performance of various ALF pavements using finite element analysis and the VEPCD model.

Behavior of Shear Dominated Reinforced Lightweight Concrete Members under Seismic Conditions
M.J. Kowalsky
Expanded Shale, Clay, and Slate Institute
01/04 to 12/06
The objective of the research described in this proposal is to develop a process by which the characteristic shear resistance under cyclic loading of various lightweight aggregates concretes can be assessed. The need for this research stems from the following reasons: (1) Small dataset of past reversed cyclic shear critical tests, (2) Relatively large scatter in experimental data that has been observed for monotonic shear critical tests, (3) Lack of consensus among major worldwide concrete codes on lightweight concrete shear performance, and (4) Potential economic impact if it shown that existing shear strength reductions are overly conservative.

Design Criteria for Post and Beam Bents with Drilled Shafts and Other Structures
M.J. Kowalsky and M. Gabr
NC Department of Transportation
07/05 to 06/07
The research described in this proposal aims to expand upon work currently underway for Pile-Bent bridge structures to all sub structure systems employed by NCDOT including spread footings and columns supported on drilled shaft foundations. The research task encompass identifying issues specific to drilled shaft bent design and selection of a series of sample structures for analysis and design, as well as structural testing of bridge sub-structure to superstructure connections.

Pile Bent Design Criteria
M.J. Kowalsky and M.A. Gabr
NC Department of Transportation
07/05 to 07/07
A detailed 3D analysis models will be used to provide a better understanding of the actual performance of NCDOT sub-structure systems (depth to fixity; connection performance, effective length factors). In addition, the proposed work aim at providing a rational basis for identification of key performance limit states (drift and strength limits) as well as design examples comparing LFD and LRFD criteria for bridge sub-structures

Influence of Low Temperatures on the Ductility of Bridge Structures in High Seismic Regions
M. Kowalsky and T. Hassan
Alaska Department of Transportation
08/05 to 07/07
Through a series of cyclic experiments on reinforced concrete circular columns at 20oC, 0oC, -20oC, -40oC and -50oC, this research will study the seismic responses of concrete structures at low temperatures. Based on the experimental results at the structural and material levels at various temperatures, ductility and seismic failure mechanisms of reinforced concrete members will be determined and design issues at low temperatures will be addressed.

Internet-Enable Laboratory Experiences for Undergraduate Civil Engineering Students
V.C. Matzen, M.A. Gabr, and Abhinav Gupta
National Science Foundation
07/03 to 06/06
This study is aimed at adaptation of recent developments in information technology for incorporation of internet-enabled civil engineering laboratory experiments in undergraduate structures and geotechnical courses. Faculty and students will be able to remotely access, run, and control these experiments either independently or in a classroom setting. Such a capability would facilitate the offering of these courses via distance learning program to provide opportunities for "non-traditional" students (e.g., part-time student, working parent, and career-changing adult) seeking careers in Civil Engineering. Implementation of this work will lead to enhancing the quality of undergraduate Civil Engineering courses and making laboratory curriculum widely accessible.

Web Based Observation and Control of an Undergraduate Civil Engineering Laboratory Experiment
Vernon Matzen (PI), Abhinav Gupta and Jim Nau
NCSU LITRE program
10/04 to 06/06
A static test of a cantilever beam in CE 324, is being modified so that it can be controlled and observed remotely using web based tools. In the web-based setup, a controller with a stepper motor will be used to operate the screw actuator, and the strains will be monitored, recorded and displayed using a PC-based data acquisition system. The research will investigate appropriate ways to protect the experiment from overloading and internet/PC malfunctions, as well as procedures for scheduling, access and security.

Evaluation of a New High Corrosive Resistant Steel Reinforcement for Concrete Structures in the Miditerian Salt Environments
National Science Foundation
T. Hassan and S. Rizkalla
09/05 to 08/07
MMFX is a high strength, highly corrosion resistant steel, ideal for use in civil engineering applications for salt environments such as the miditerian environment in Egypt and high humidity climate such as in North Carolina and many other ocean exposed states. The research will introduce the MMFX steel as a new material has a high corrosion resistance to the engineering community in Egypt for the first time. The proposed research project consists of three major tasks; (i) experimental work, (ii) analytical phase, (iii) development of design guidelines.

Corrosion Inhibitors for Concrete Bridges
A. Mirmiran and S. Rizkalla
NC Department of Transportation
07/02 to 12/04
The research project evaluates the effectiveness of commercially available corrosion inhibitors for remediation purposes in delaying, slowing, stopping or reversing the corrosion process in existing concrete under laboratory conditions of wet-dry cycles and salt water spray, simulating severe field conditions. The results will be used to compare the effectiveness of corrosion inhibitors at different levels of chloride contamination and establish the threshold beyond which surface application does not provide any significant improvement. The project will develop guidelines and specifications for surface treatment using corrosion inhibitors and recommend means to incorporate surface treatment scheduling in bridge inspection and maintenance plans for NCDOT.

Innovative Textile Technology for Modular Bridge Decks
S. Rizkalla
National Science Foundation
07/03 to 12/05
This research program is designed to, for the first time ever, adapt the 3-D weaving process to develop innovative FRP bridge decks. The work plan has both experimental and analytical components. The experimental work consists of testing scale models of FRP decks as well as coupon testing under static and fatigue loading. The analytical work includes finite element modeling of the FRP decks using micro- and macro-models. Once the models are calibrated using the experimental results of Part I, a parametric study will be carried out to optimize the shape and configuration of the deck.

Value Engineering and Cost Effectiveness of Various FRP Repair Systems - Part II
S. Rizkalla
North Carolina Department of Transportation
07/05 to 06/06
This research program is an extension of NCDOT Project 2004-15: Value Engineering and Cost-Effectiveness of Various FRP Repair systems, which will be completed in June 2005. Results of Project 2004-15 and the proposed extension will be used to produce complete design guidelines. The project will provide bridge maintenance engineers with a comprehensive document to select the most appropriate repair or strengthening systems along with the cost effectiveness and value engineering for each system.

I/UCRC Center, "Repair of Buildings and Bridges with Composites (RB2C)
S. Rizkalla
National Science Foundation
07/02 to 06/07
The NSF Industry/University Cooperative Research Center entitled "Repair of Buildings and Bridges with Composites" (RB2C), is located at the Constructed Facilities Laboratory, North Carolina State University (NCSU). The Center is working in collaboration with the Center located at the University of Missouri-Rolla (UMR). The Center at NCSU focuses on the needs of the construction industry in development of new and innovative structural components as well as strengthening/repair methods for existing structures using advanced composite materials.

Evaluation of Bond Characteristics of MMFX Steel
S. Rizkalla
MMFX Technologies Corporation
07/05 to 06/07
The high-strength steel commercially known as Micro-composite Multi-structural formable (MMFX) steel could lead to potential savings through the use of lower reinforcement ratios due to it's higher strength. However, a critical evaluation of the bond characteristics of MMFX steel with concrete is of paramount importance, especially if high strength is to be utilized. The proposed research will deeply investigate the bond behavior of MMFX steel to concrete. The first phase of the proposed research program will include the parameters believed to significantly affect the bond strength: concrete compressive strength, bar size, concrete clear cover, and confinement level. Three universities are participating in this study, namely, University of Texas at Austin, The University of Kansas, and North Carolina State University. Each university will test twenty-two full-scale splice beams for the first phase of the program.

Bond Behavior of SAS High Strength Steel
S. Rizkalla
SAS Stressteel, Inc.
2004-2005
To evaluate the bond characteristics of the SAS high tensile strength steel using end-block and splice beam test specimens according to the ICC specifications.

Torsion Behavior of Precast Prestressed Ledger Beams
S. Rizkalla and P. Zia
Metromont Corporation
09/05 to 12/05
The objective of this project is to evaluate the behavior of precast prestressed ledger beams under the effect of eccentric loading of precast beams typically used for parking structures. Two full size beams with spans of 30 and 45 feet will be tested using double T-beams to load the beams up to failure. Four different reinforcement details are considered in this integration.

Development of Repair Systems for Steel Structures and Bridges
S. Rizkalla
Mistubishi Chemical America
07/02 to 06/07
The project investigates the use of high modulus carbon fiber polymer (CFRP) material for strengthening steel structures and bridges. The material in use now is in the form of sheets and strips bonded to the tension surface of steel structures. The first phase includes selection of the appropriate resin and bond characteristics of the material. The second phase is to test large-scale steel monopoles strengthening with different materials, configurations and subjected to static and fatigue loading conditions. The study will be continued to include the environmental effect on the strengthening system.

Evaluation of New Generation of Adhesives for Marine Structures
S. Rizkalla
IPS Corporation
07/02 to 06/07
The project investigates the behavior and material characteristics of two proposed adhesives designed for marine structures. The project is mainly an experimental study at this stage. The experimental program initially consists of lap shear test to determine the bond characteristics of two adhesives between two surfaces; each consists of Carbon Fiber Reinforced Polymer (CFRP) and steel surface. A specially designed insulated room has been constructed at the Constructed Facilities Laboratory to house the instrumentations, which were built to subject the specimens to the specified environment.

An Innovative Bridge Deck System
S. Rizkalla
Martin Marietta Composites
07/02 to 06/07
The research includes development of an innovative system for highway bridge decks. The system is also suitable for manufacturing trailer walls using small thicknesses. The innovative concept consists of two layers of 2-D fiber pultruded sheets and styrofoam layers in between to provide the required thickness. At a later stage, bundled fibers are inserted in the third direction to increase the strength through-thickness properties of the panels. The system is a modified process for the Z-technology used for the aerospace industry. The test program consists of different tests to examine the material characteristics as well as the behavior of the panel.

Supplement Funding to Support Undergraduate Student
S. Rizkalla
National Science Foundation
07/03 to 06/06
Efforts at repair of steel bridges with FRP have not been very successful because of low modulus of most FRP materials as compared to steel. The new carbon fibers have high modulus of elasticity that is about 3 times that of steel in fiber form and twice that of steel in laminate form. The student will be involved in an experimental plan consisting of testing the fibers with a variety of resins to identify the most effective and compatible resin for the repair of steel. Tests will include laminates as well as bond with steel plates.

Wireless Sensor Networks for Structural Health Monitoring of Bridges
S. Rizkalla
National Science Foundation
07/03 to 12/05
The research project deals with structural health monitoring of bridges and civil engineering buildings. The first part addresses sensing/data interpretation, the second part addresses the transfer of data from sensors to the location interpretation occurs. The proposal ties together the expertise of the two NSF-I/UCRC Centers at NC State, RB2C in the Department of Civil Engineering and CACC in the Electrical and Computer Engineering Department. The specific issue is the wireless communication of data for structural health monitoring of civil engineering structures.

Macromolecular Science and Infrastructure Engineering
S. Rizkalla (Co-PI with Virginia Tech)
National Science Foundation
09/01 to 08/05
The Integrated Graduate Education Research and Traineeship (IGERT) Program provides the opportunity for our graduate students to conduct an interdisciplinary research in Macromolecular Science and Infrastructure Engineering, focused on polymeric adhesives and composites in civil engineering structures. The program allows collaboration between the following seven departments: Chemistry, Engineering Science, Civil Engineering, Electrical Engineering, Computer Engineering, Wood Science and Marketing from four colleges, including NC State University. It will include exchange of students and faculty members, as well as development of new courses in the field of infrastructures.

Application of the LRFD Bridge Design Specifications to High-Strength Structural Concrete Flexure and Compression Provisions
S. Rizkalla, A. Mirmiran, and P. Zia
Cooperative Research Programs, Transportation Research Board (NCHRP)
05/03 to 08/06
The objective of this research is to develop recommended revisions to the AASHTO LRFD Bridge Design Specifications to extend the applicability of the flexural and compression design provisions to concrete up to 18 ksi. The research results will allow full utilization of the material characteristics and greater use of high-strength concrete, since the current LRFD limits the design strength of the ultimate compressive strength of concrete to 69 MPa (10 ksi). The results will have great economical advantages by allowing bridge design engineers to design AASHTO girders more effectively in terms of the thickness of the web and larger beam spacing.

Evaluation of MMFX Steel for NCDOT Concrete Bridges
S. Rizkalla and P. Zia
North Carolina Department of Transportation
07/04 to 12/05
This research project investigates the effectiveness of highly corrosive, resistant, high strength steel reinforcements, recently patented as MMFX Steel, for use in highway concrete bridge applications. The experimental program consists of multiple phases to examine the mechanical properties, effect of bend and corrosion resistance claimed by the manufacturer. The structural performance includes full-scale concrete bridge decks. The analysis will be based on non-linear-finite elements to determine the influence of other parameters, which could affect the design. The research will provide design guidelines for the use of this new tool.

Lateral Flange Bending in Heavily Skewed Bridges
E.A. Sumner
NC Department of Transportation
07/06 to 12/08
Today's steel plate girder bridges are more commonly constructed with long spans and a heavy skew. As a result, an increase in problems with lateral flange bending of the steel plate girders during construction has been observed by the NCDOT. Lateral flange bending induces additional stresses into the flanges of the girders, the end-bent diaphragms, the intermediate cross-frames, and the support bearings. The focus of this research is to quantify the effects of lateral flange bending, establish a method to predict the effects, and develop strategies to mitigate the effects of heavy skew on lateral flange bending. A combination of field monitoring and finite element analysis will be utilized to accomplish these objectives.

Digital Recording of Large Scale Structural Testing for use in Undergraduate and Graduate Civil Engineering Classrooms
E.A. Sumner
NCSU-LITRE
01/06 to 06/07
Laboratory demonstrations are an essential aspect of many engineering classes that improve a student's understanding of fundamental concepts by allowing them to associate theoretical concepts and calculations with observed behavior. The objective of this project is to develop a system to record still images, video, sound, and test data into a format that can be played back in real time or at an accelerated rate. The system will be used to document numerous full-scale structural tests conducted at the NCSU Constructed Facilities Laboratory. These recordings will be stored on the web for use in civil engineering courses.

Full Scale Testing of Overhang Falsework Hangers on NCDOT Modified Bulb Tee (MBT)
E.A. Sumner
NCDOT
07/04 to 12/05
In the design of the overhang falsework systems, the ultimate strength and safe working load capacity of falsework hangers on modified bulb tee (MBT) prestressed concrete girders is not wholly known. The analysis procedures used by the manufactures and NCDOT to predict the strength of the hangers on MBT girders are not consistent and may have resulted in conservative and more costly falsework designs. The focus of this research is to determine the ultimate strength and safe working load capacity of falsework hangers on MBT girders through full scale testing and analytical investigation.

Developing a Simplified Method for Predicting Deflection in Steel Plate Girders Under Non-Composite Dead Load for Stage-Constructed Bridges
E.A. Sumner and S. Rizkalla
NCDOT
07/03 to 12/05
Matching the final bridge deck elevations in stage constructed steel girder bridges has created numerous problems during construction. Misaligned deck elevations between two stages may require grinding of the deck surface or result in reduced concrete cover leading to early deterioration of the bridge deck. The objective of this research is to develop an empirically based method to predict the non-composite deflection of steel plate girders in staged-constructed bridges. The formulation of the simplified method will require a combination of field measured data and extensive three-dimensional analytical simulation.

RC Beams Strengthened with Near Surface Mounted FRP
Jin-Guang Teng, S. Rizkalla, and B. Taljsten (Sweden)
Hong Kong National Research Council
01/05 to 12/07
The project investigates the use of fiber reinforced polymer (FRP) material to strengthen reinforced concrete (RC) beams to increase their flexural and shear capacity. The project at Hong Kong will focus on installing these materials into the tension zones of the flexural members using the near surface mounted technique. The project complements the research in progress at North Carolina State University sponsored by the North Carolina Department of Transportation using 43-year old prestressed c-channels and AASHTO girders. The research findings will be greatly enhanced by the collaboration with the University of Technology, Sweden.

Debonding Failure in CFRP Strengthened Steel Structures
X. Zhao (Monash University), S. Rizkalla, and R. Al-Mahaidi (Monash University)
Australian Research Council
01/05 to 12/07
The research will make a breakthrough in understanding the bond characteristics between CFRP and steel. It will enhance the capacity of Australian researchers to participate in a new cutting-edge research area, and help create a vibrant new industry for strengthening steel structures. The project will contribute to improved cost efficiency and safety of steel structures thereby contributing to the socio-economic well being of Australia and the USA including road, offshore, building and mining industries.

An Exploratory Study of a Test Device for Concrete Permeability
P. Zia
National Science Foundation
03/03 to 08/05
The objectives of this exploratory research are to further develop and refine the test method and a device for measuring air permeability of concrete. More specifically, the research will address four critical issues: (1) determine the effect of the moisture content of concrete on air permeability, (2) explore techniques to dry the concrete surface to a sufficient depth to eliminate the effect of moisture content, (3) improve the test device so as to increase the depth of air flow into the concrete, and (4) establish an appropriate procedure for the concrete surface preparation in the field so that the test device can be applied successfully.