Beckett C.,U.S. Federal Highway Administration |
Beckett C.,Professional Service Industries Inc. |
Ocel J.,U.S. Federal Highway Administration
Transportation Research Record | Year: 2016
Modern technologies for plasma cutting have the potential to produce bolt holes that perform on a par with those made by currently accepted methods and at the same time to reduce fabrication costs related to steel bridge construction. Current specifications do not allow holes in primary members to be formed by using plasma cutting. A lack of data showing how plasma-cut holes perform under fatigue and tensile loading inhibits their use in secondary members as well. This paper presents findings from an ongoing investigation into the structural performance of steel members with plasma-cut bolt holes. Specimens include members with a single plasma-cut hole and connection members. Material with plasma-cut holes was procured from four fabricators throughout various industries. Results from approximately 170 fatigue tests and 34 tensile tests are presented. Data from the fatigue tests show that under certain conditions, plasma-cut bolt holes perform comparably to drilled and punched holes. Results from tensile testing are mixed, with 29 of 34 tests exhibiting brittle failure, and most test specimens exceeding the tensile strength of the material. Geometric properties of the plasma-cut holes were measured as well and did not meet current specifications. © 2017, American Association for the Advancement of Science. All rights reserved.
Zhang G.,Professional Service Industries Inc. |
Harichandran R.S.,Michigan State University |
Harichandran R.S.,University of New Haven |
Ramuhalli P.,Pacific Northwest National Laboratory
NDT and E International | Year: 2012
Delamination of concrete bridge decks is a commonly observed distress in corrosive environments. In traditional acoustic inspection methods, delamination is assessed by the hollowness of the sound created by impacting the bridge deck with a hammer or bar or by dragging a chain. The signals from such sounding methods are often contaminated by ambient traffic noise and delamination detection is highly subjective. In the proposed method, a modified version of independent component analysis (ICA) is used to filter the traffic noise. To eliminate subjectivity, mel-frequency cepstral coefficients (MFCC) are used as features for delamination detection and the delamination is detected by a radial basis function (RBF) neural network. Results from both laboratory and field data suggest that the proposed method is noise robust and has satisfactory performance. The method can also detect the debonding of repair patches and concrete delamination below the repair patches. The algorithms were incorporated into an automatic impact-based delamination detection (AIDD) system for field application. © 2011 Elsevier Ltd. All rights reserved.
Zmetra K.,Professional Service Industries Inc. |
Zaghi A.E.,University of Connecticut |
Wille K.,University of Connecticut
Structures Congress 2015 - Proceedings of the 2015 Structures Congress | Year: 2015
The end corrosion in steel girders at the bearings due to joint leakage is a significant problem in many of the old bridges around the nation. This critical damage impairs the shear and bearing capacities of girders. This paper discusses a novel method for retrofitting the corroded ends of steel bridge girders using ultra-high performance concrete (UHPC) encasings. This repair method involves casting thin UHPC panels on each side of girder web. Shear studs welded to undamaged portion of the web and flange engage the UHPC panels and provide an alternate load path. This repair method is expected to be superior to the current practice of attaching steel cover plates. It can be easier to design and install, reduce obstruction to traffic during the repair, prevent future corrosion to the girder end, and reduce the total cost of repair. To investigate the effectiveness of the repair in recovering the capacity of the corrosion damaged girders, three large-scale experiments were performed on the undamaged, damaged and repaired rolled girders. It was found that a 1 3/4-in. thick UHPC panel cast two-third of the height of the girder effectively restores the bearing capacity. A high fidelity finite element model was created from the results of the large-scale experiments. This model was then used to design eight repair techniques for full size plate and rolled girders with heavy corrosion damage. This innovative repair method may offer the bridge design community a superior alternative retrofit method for large scale application on our aging bridges.
Kim J.-Y.,Georgia Institute of Technology |
In C.-W.,Professional Service Industries Inc. |
Sun K.H.,System Dynamics |
Song J.S.,System Dynamics |
Lee J.-H.,Naru EMS Inc.
Composite Structures | Year: 2016
This research develops a nondestructive evaluation (NDE) technique to obtain images of two types of defects, delamination and debonding, in a thick laminate composite plate as a laboratory material system for wind turbine blades. The technique uses focused shear waves which are generated and detected by a set of noncontact, air-coupled ultrasonic transducers. The noncontact nature of the air-coupled method facilitates rapid scanning/inspection of large composite structures. Ray-tracing simulations are performed which visualize the focusing behavior of the focused shear waves in the specimen, from which the experimental parameters are determined. The proposed focused shear wave technique is compared with a Lamb-wave based technique, showing that the present technique is more appropriate for direct imaging of these defects. The obtained images of delamination and debonding defects agree well with the estimated defect locations and dimensions. This demonstrates the feasibility of further developing the present technique for specific field applications in wind turbine blades. © 2016 Elsevier Ltd
Usluogullari O.F.,Ankara University |
Duman E.S.,Ankara University |
Sahin H.,Professional Service Industries Inc.
Landslides and Engineered Slopes. Experience, Theory and Practice | Year: 2016
In this study, the movement of a slope and the performance of the stabilizing piles are investigated. A landslide-prone area, where soil movements are observed, is selected to perform the investigation. The stratigraphic characteristic of the slope is identified with a testing program to develop a stabilizing approach to minimize the potential landslide risk. Therefore, finite element analyses are performed by using various piles to determine the optimum pile configuration based on factor of safety, maximum displacements, bending moments, and shear forces. The investigated area has two steeper slopes: one is closer to the road construction, and the other is located on the top of slope. According to the results of the analyses, the variation of maximum soil displacement is insignificant, although slight variations of the factor of safety, maximum shear force and bending moment are determined for two and three rows of piles. The results show that the piles are more effective when located in the middle of the slope. Besides, they are less effective in the case of increasing the rows of piles due to high bending moments and shear forces. © 2016 Associazione Geotecnica Italiana, Rome, Italy.
Ou Y.-C.,National Taiwan University of Science and Technology |
Alrasyid H.,Sepuluh Nopember Institute of Technology |
Haber Z.B.,Professional Service Industries Inc. |
Lee H.-J.,National Yunlin University of Science and Technology
ACI Structural Journal | Year: 2015
Double-curvature cyclic tests of large-scale columns were conducted to investigate the seismic performance of precast highstrength reinforced concrete (RC) columns. High-strength concrete and high-strength longitudinal and transverse reinforcement were used. The use of grouted coupler splices for the high-strength longitudinal reinforcement in the plastic hinge zone and the use of butt-welded splices for the high-strength transverse reinforcement were examined. Test results showed that precast columns with the grouted coupler splices exhibited comparable seismic performance with monolithic counterparts. The butt-welded splice had a negligible effect on the tensile behavior of the spliced bars. However, precast columns with such welded splices in transverse reinforcement showed smaller ultimate drift capacities than their counterparts with hooked transverse reinforcement. This was due to the reduced resistance of butt-welded transverse reinforcement to buckling of longitudinal reinforcement. Shear, flexural, and confinement design equations for the precast high-strength columns were discussed by comparing with the test results. © 2015, American Concrete.
Chen L.,Professional Service Industries Inc. |
Graybeal B.A.,Turner Fairbank Highway Research Center
Journal of Bridge Engineering | Year: 2012
The concrete-damaged plasticity (CDP) model with proposed material properties replicated the observed deflection and strain responses of three experimentally tested I-girders and was determined to be consistent for different spans under both flexural and shear tests. In this study, the CDP model was further tested in modeling the behaviors of a prestressed second-generation ultrahigh-performance concrete (UHPC) pi-girder. The computational aspects include discussion of the various parameters that influenced the accuracy of the model and investigation of the scenarios regarding the limits that are useful for further optimization of the girder. The CDP model was reconfirmed to be consistent and reliable in replicating the observed structural response of both the UHPC pi-girder and a modified structural configuration referred to as the "UHPC pi-girder-with-joint. " The finite-element analysis modeling techniques developed herein are expected to be valuable in the future development of additional UHPC structural components. © 2012 American Society of Civil Engineers.
Chen L.,Professional Service Industries Inc. |
Graybeal B.A.,Structural Concrete Research Program Manager
Journal of Bridge Engineering | Year: 2012
Abstract Ultrahigh performance concrete (UHPC) is an advanced cementitious composite material that has been developed in recent decades. When compared with more conventional cement-based concrete materials, UHPC tends to exhibit superior properties such as increased durability, strength, and long-term stability. This computational investigation focused on modeling the structural behaviors of UHPC components including prestressed UHPC AASHTO Type II girders. The concrete damaged plasticity model was tailored to model UHPC within a commercially available finite-element analysis package. This manuscript focuses on modeling three UHPC I-girders tested under flexural or shear loading configurations. The concrete damaged plasticity model was demonstrated to replicate both linear and nonlinear structural responses of I-girders reasonably well. A set of UHPC constitutive properties were developed that facilitate the model replication of the local and global responses observed in the series of physical tests. © 2012 American Society of Civil Engineers.
Zhang G.,Professional Service Industries Inc. |
Graybeal B.A.,Professional Service Industries Inc.
Journal of Bridge Engineering | Year: 2015
Ultrahigh performance concrete (UHPC) presents many superior properties, such as advanced strength, durability, and long-term stability. The use of existing cross section geometries for materials with advanced properties results in inefficient designs and less cost-effective solutions. This study focused on developing a series of finite-element optimized sections of pi-girders to effectively utilize the superior mechanical properties of UHPC over span lengths of up to 41 m (135 ft). The research was performed using a finite-element model that has been calibrated and verified against experimental results. The optimization was progressively conducted at local, element, and structural levels. At the local level, the focus of the investigation was to find the optimal deck thickness and prevent transverse bending failure of the deck. At the element level, sectional parameters, including girder height, bulb size, web thickness, and strand layouts, were investigated to find the minimal sectional size that accommodates standard loads for a span length of 23 m (75 ft) or above. At the structural level, deflection under a live load was checked such that the bridge system using the proposed sections can meet the deflection requirements specified in guidelines. Four cross sections based on the second generation pi-girder were proposed, and a design chart was provided to facilitate preliminary design for bridge engineers. © 2014 American Society of Civil Engineers.
Amir-Faryar B.,Professional Service Industries Inc. |
Finnen R.E.,Professional Service Industries Inc.
Geotechnical Special Publication | Year: 2015
Piedmont residual soils (PRS) comprise much of Virginia, Georgia, and the Carolinas. Thus, a better understanding of their stiffness properties is of paramount importance. The hallmarks of the soils within the Piedmont region are their low Standard Penetration Test (SPT) blow counts, saprolitic and its silty nature. To understand the stiffness properties of PRS, geotechnical exploration and in situ testing were conducted using SPT and Flat Dilatometer (DMT) testing. The results of the geotechnical explorations and in situ testing were studied and used to predict the settlement of the PRS. The results of the predicted settlement calculations were verified with the post-construction monitoring data and the recommendation of a method to predict the settlement of Piedmont soils was provided. © ASCE 2015.