Category: Seminars

The Aging Properties of SBS Modified Bitumen and Its Recycling

Civil Engineering CE 5990 Graduate Seminar

Thursday, January 19
Time: 4–5 p.m.
Location: Dow 642

Public is welcome

Speaker: Dr. Xiaoming Huang, Professor, Associate Dean, School of Transportation, Southeast University, China Brief

Abstract: In China, following the huge new highway constructions, large portion of the highway network needs to be maintained and rehabilitated. Reclaimed asphalt material has been studied, produced and used for pavement rehabilitations. This lecture will cover the study of aging of the modified asphalt binder, the influence of mineral filler and trichloroethylene. The lecture will also cover an introduction of research in pavement engineering in China as well as the research in Southeast university in China.


Two- and Three-Dimensional Micromechanical Constitutive Modeling of Heterogeneous Infrastructure Materials with X-Ray Computed Tomography Images

Civil Engineering CE 5990 Graduate Seminar

Thursday, Jan. 12
Time: 4-5 p.m.
Location: Dow 642

Public is welcome

Presenter: Dr. Qingli Dai, Assistant professor, Department of Civil and Environmental Engineering.

Abstract: This study developed two-dimensional (2D) and three-dimensional (3D) micromechanical finite element (FE) models to study the viscoelastic properties of heterogeneous infrastructure materials. For example, asphalt mixtures are consisted of very irregular aggregates, asphalt matrix and a small amount of air voids. The internal microstructure of asphalt mixtures was captured with X-ray Computed Tomography (CT) imaging techniques. The 2D and 3D digital samples were created with the reconfiguration of the scanned slice images. The FE mesh of digital samples was generated with the locations of image pixels within each aggregate and asphalt matrix. Along the boundary of these two phases, the aggregate and matrix FEs share the nodes to connect the deformation. The micromechanical FE modeling was conducted by incorporating the captured microstructure and ingredient properties (viscoelastic asphalt matrix and elastic aggregates). The generalized Maxwell model was applied for viscoelastic asphalt matrix with calibrated parameters from the nonlinear regression analysis of the lab test data. The 3D simulation with digital samples generated better prediction than the 2D models. These favorable comparison results indicate that the developed micromechanical FE models have the ability to accurately predict the global viscoelastic properties of the heterogeneous infrastructure materials.


An EXtended Finite Element Model (XFEM) for Predicting Crack Propagation within Infrastructure Materials

Thursday, Jan. 12
Time: 4-5 p.m.
Location: Dow 642

Public is welcome

Presenter: Kenny Ng, Ph.D. candidate, Department of Civil and Environmental Engineering, (Adviser: Dr. Qingli Dai).

Abstract: The object of this study is to employ XFEM and image analysis techniques to numerically investigate crack propagation within infrastructure materials. The XFEM has been recently developed to eliminate remeshing by allowing crack propagation within continuous elements. The discontinuous crack and inclusion enrichment functions with level set method (LSM) were addressed in the XFEM. The crack growth angle and stress intensity factors (SIFs) were also formulated to predict the crack growth direction. The XFEM was developed with MATLAB program for predicting micro-crack behavior with Compact Tension (CT), single-edge notched beam (SEB) and indirect tension (IDT) tests. The developed XFEM was firstly validated with CT and SEB tests on a homogeneous sample. In order to capture the real material microstructure, the digital samples were generated with imaging processing and ellipse fitting techniques. The predicted crack propagation with XFEM simulation on digital samples was compared with fracture pattern of lab-tested SEB and IDT specimens. The comparison results on open-mode middle-notched and mixed-mode offset-notched SEB and IDT tests indicate the developed XFEM has the ability to accurately predict fracture behavior within heterogeneous infrastructure materials. In addition, the internal frost-induced damage within an idealized pore system was also analyzed and simulated using XFEM.


The I 35W Bridge Collapse: A Design Error or a Lesson?

Our last Civil Engineering Seminar of this semester will be presented by Bill Kallman, P.E.. He is a retied bridge engineer from the NYDOT and he maintains a local consulting office in Hancock.

December 8, 2011 4:00 p.m. #642 Dow. Public welcome.

Presentation outline

  1. Pictures of Bridge Pre & Post-Collapse
  2. History of Preliminary Decisions, Materials and Design Specifications
  3. Film of Collapse From Security Camera
  4. FHWA Finite Element Analysis of Truss and Gussets, one of three
  5. Gusset U10 Analysis by Wiss Janey Elsner
  6. Order of Collapse
  7. Construction on Bridge
  8. MnDOT Inspections
  9. Pavement Pressure, See TRR 1627
  10. Call for M.T.U. Research on Pavement Push Research

The Michigan Cone Tests: A Reliability Study

Our Civil Engineering Seminar of this week will be presented by three
graduate students: Michael Hochscheidt, Karl Krueger, and Tony Oxley.
Public welcome.

Name

Karl Krueger

Advisor

Dr. Stanley J. Vitton

Abstract

The Michigan cone test is a compaction control test used to determine the maximum density of granular materials. This test has been used in Michigan as a field compaction test for over 50 years. However, the Proctor test is more often used as a method of compaction control in other states. Recently, the question has risen concerning the reliability of the cone test compared to methods used in other states. Specifically, does the Michigan cone test lead to better overall compaction control than use of the Proctor test would? Specific questions concerning the cone test include: how was the test developed, does the cone test yield a greater maximum density than the Proctor test, is the cone test repeatable between multiple technicians, and what should be done for quality assurance testing on MDOT projects. The purpose of this report is to:

  • Research the origins of the cone test and gain insight into the compaction principles behind it.
  • Better answer how well the cone test compares to testing employed by other DOT agencies.
  • Determine the repeatability of the cone test for a single user as well as for multiple users.
  • Make recommendations regarding the continued use of the cone test.

Comparison of Three Methods for Driven Pile Capacity

Our Civil Engineering Seminar of this week will be presented by three
graduate students: Michael Hochscheidt, Karl Krueger, and Tony Oxley.
Public welcome.

Name

Tony Oxley

Adviser

Stan Vitton

Abstract

Several different methods for determining pile capacity are in use today. Three of these methods were evaluated to determine the accuracy of the predictions with regards to the actual capacity determined from testing. After analyzing the data the most accurate method for all soil types appeared to be the Army Corps method. The DRIVEN program was shown to be extremely inaccurate in cohesionless soils, and the API method was fairly close to the Army Corps method. It was also determined that no trends due to pile size, type or material or soil strength were present. However, there was significant variability in the data, so it is recommended that additional testing and analysis be performed to confirm the conclusions reached.


Cut Slope Design for the Access to an Underground Copper Mine

Our Civil Engineering Seminar of this week will be presented by three
graduate students: Michael Hochscheidt, Karl Krueger, and Tony Oxley.
Public welcome.

Name

Michael Hochscheidt

Advisor

Dr. Stanley J. Vitton

Abstract

Slope stability analysis is a major area of research in geotechnical engineering. That being said, very little is written in the geotechnical engineering literature on the design of box-cuts. The goal of this thesis will be to investigate the proper design of a box-cuts, and to design a box-cut for access to an underground copper mine. Issues that need to be considered in the box-cut design include, long term dewatering design, slope stability analysis, and erosion control. The soils at the project site were extremely low permeability, as a result a system of ejectors was designed both to improve the stability of the slopes and prevent flooding. Based on the results of limit equilibrium analysis and finite element analysis, a slope design of two horizontal on one vertical was selection, with a rock fill buttress providing reinforcement. Finally, Michigan DOT standards for seeding were used to provide erosion control.


Bond Strength between UHPC and Normal Strength Concrete (NSC) in accordance with Split Prism and Freeze-Thaw cycling tests

Civil Engineering CE 5990 Graduate Seminar
Three graduate students will present their research topics in our Civil
Engineering Seminar. This Thursday- 4-5PM 11/10/2011, Dow 642

Miguel Angel Carbonell

CEE Graduate Student

Abstract

The rehabilitation of concrete structures, particularly within transportation infrastructure network is a major challenge for transportation agencies in the United States. This is especially true for concrete bridge decks, which are often subjected to severe operating conditions, both environmental and man-made. Often, the most appropriate strategy to preserve or rehabilitate these structures is to provide some form of a protective coating or barrier. These surface treatments have typically been some form of polymer, asphalt, or low-permeability concrete, but the application of UHPC (Ultra High Performance Concrete) has shown promise for this application mainly due to its negligible permeability, but also as a result of its excellent mechanical properties, self consolidating nature, rapid gain strength and minimal creep and shrinkage characteristics. However, for widespread acceptance, durability and performance of the composite system must be fully understood, specifically the bond between UHPC deck and normal concrete typical for bridge decks. It is essential that the bond offers enough strength in order to resist the stress due to mechanical loading or thermal effects while also maintaining an extended service-life performance.

An experimental study was performed to assess the bond performance of UHPC for overlay applications. Pre-wetting conditions, surface preparation, freeze-thaw cycling and indirect tensile strength were variables taken into account to study such performance. A total of 60 composite and 7 monolithic concrete specimens, 102x76x394 mm, were cast to test in indirect tension. Experimental results showed that samples subject to 300 freeze-thaw cycles present greater bond strength than samples of the same age without freeze-thaw cycles, and all samples in which the moisture condition of the substrate is saturated before placing UHPC achieves excellent bond strength which amply satisfies the range specified in the ACI Concrete Repair Guide.


Probabilistic Analysis via Aeroelasticity and System Identification on Wind Turbine Blades for Operational Structural Integrity Assessment

Civil Engineering CE 5990 Graduate Seminar
Three graduate students will present their research topics in our Civil
Engineering Seminar. This Thursday- 4-5PM 11/10/2011, Dow 642

Antonio Velazquez

Ph.D Student

Abstract

Wind energy is an increasingly important component of this nation’s renewable energy portfolio. Safe operation of wind turbine structures requires not only information regarding their condition, but their operational environment. Given the difficulty inherent in SHM processes and the stochastic nature of wind loads, a probabilistic framework is appropriate to characterize their risk of failure at a given time. Such information will be invaluable to turbine controllers, allowing them to operate the structures within acceptable risk profiles. A modified along-wind aeroelastic analysis adopting rotationally-sampled wind-field spectral functions is studied in combination with modal subspace identification tecnhiques, such as Eigensystem Realization Algorithm (ERA) and Partial Observer Markovs (POM). The study further explores characterization of the turbine loading and response envelopes for critical failure modes of the turbine blade structures.