Seminars

“Bad Things That Can Happen to Good Concrete”
Seminar Monday, November 16, 2009,12:00 – 12:45 PM, CSEB-B17
Michael A. Ozol, PhD, Geologist/Petrographer, Concrete and Materials
Almost all the concrete that is placed in service performs well throughout its service life and exhibits no problems related to inadequate strength or to poor durability under the conditions of service exposure. But some concrete, a very small fraction of all the concrete in place, does not perform satisfactorily and exhibits manifestations of distress. Some obvious manifestations which call attention to a problem in the concrete are cracking, excessive expansion, excessive shrinkage, excessive deflection, loss of strength, and loss of surface material, as by spalling and scaling. Each of these types of distress can result from several causes, either singly or in combination. Examples of some causes of concrete distress are discussed and illustrated.

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“Molecular Hydraulic Property of Na-Montmorillonite Interlayer”
Seminar Monday, Nov. 23, 2009,12:00 – 12:45 PM, CSEB-B17
Priyanthi Amarasinghe, PhD, Johns Hopkins University

Na-montmorillonite is a clay mineral which swells when a sufficient amount of water fills the inter-particle and intra-particle spaces. When swelling occurs it exerts high pressure often causing severe distress to infrastructure such as building foundations, roads, retaining walls, etc. On the other hand swelling nature is a critical factor for using this type of clay as liners in geoenvironmental engineering. Therefore, in order for a better prediction of clay swelling behavior a thorough understanding of clay-fluid molecular interaction is extremely important. This study investigates the flow properties of Na-montmorillonite interlayer using XRD (x-ray diffraction) and FTIR (Fourier transform infrared spectroscopy) as the characterization techniques.

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“Topology optimization algorithms for engineering design ”
Seminar Monday, Oct. 26, 2009,12:00 – 12:45 PM, CSEB-B17
James Guest, PhD, Associate Professor at Johns Hopkins University

Since the seminal work of Bendsoe and Kikuchi in 1988, the potential power of topology optimization as a free-form design tool has been apparent. Yet numerous theoretical, numerical, and practical challenges have inhibited its capacity to produce useful engineering solutions. This seminar will present algorithms for overcoming these challenges, including schemes that control optimized structure geometry in a computationally efficient and clearly defined manner. Applications to materials, mechanisms, and structures governed by a variety of physics will be introduced.

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“A Discussion for Undergraduate Students Interested in Graduate School ”
Seminar Monday, Oct. 19, 2009,12:00 – 12:45 PM, CSEB-B17
Lori Graham-Brady, PhD, Associate Professor at Johns Hopkins University

This seminar will feature an open format discussion on graduate school led by Professor Graham-Brady. Planned topics include guidance on exploring the wide variety of civil engineering graduate school choices that are available, financial support for students pursuing graduate work in engineering, different admission styles for graduate programs, tips for getting ready to apply to graduate school (taking the GRE, selecting references, etc.) and more.

"Acceleration Tracking Control and Substructure Method in Shake Table Tests"
Seminar Monday, Oct 5, 2009, 12:00 – 12:45 PM, CSEB-B17
Narutoshi Nakata, Professor, Department of Civil Engineering, Johns Hopkins University

Recent developments in large-scale shake table facilities in US and Japan have significantly improved dynamic testing capabilities for seismic performance assessment of structures. However, challenges in shake table tests are not limited to scale issues, and a number of limitations still exist. This presentation will discuss research needs in shake table tests to enhance the dynamic testing capabilities for structures, in particular issues associated with dynamic boundary conditions and acceleration control of shake tables. Specific research efforts that are currently undertaken at Hopkins are also presented. Those efforts include the acceleration trajectory tracking control of shake tables and the substructure shake table test method.

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"Ship Hydrodynamics and the Experimental Study of Breaking Bow Waves "
Seminar Monday, Oct 5, 2009, 12:00 – 12:45 PM, CSEB-B17
Eric Maxeiner, PhD, University of Maryland
Researcher for Department of Civil Engineering, Johns Hopkins University

Ship hydrodynamics is a discipline that has been practiced for thousands of years but only truly understood for about 100 years. The ability to predict ship resistance and was more art than science until the late 1800’s when the principals of fluid mechanics were properly applied. The key is to account for the different components of drag that affect a moving ship.

Fast moving ships create large breaking waves at their bows. These waves contribute not only to resistance but also detectability because of the splash, underwater noise and resulting bubbly wake. The mechanics of breaking bow waves have been studied experimentally using a unique 2D+T wave maker which simulates ship waves without the need for a hull model. A parametric series of wave maker motions are tested to relate fundamental components of bow shape with resulting wave characteristics. The nature of the test set up allow for previously unattainable measurements of wave geometry.

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"Design criteria related to vibrations of railway bridges "
Seminar Monday, Sept 28, 2009, 12:00 – 12:45 PM, CSEB-B17
Tak Igusa, Professor, Department of Civil Engineering

Railroad traffic on bridges induces vibrations which could possibly have an adverse effect on passenger comfort. At extreme cases, vibrations from an improperly design bridge could cause derailment. Design codes for bridges contain criteria which would prevent such vibration problems. While some of these criteria are well founded, there are a few that are overly restrictive, resulting in excessively stiff railway bridges. The seminar will focus on a criterion based on the natural frequency of the bridge. Using basic principles of structural mechanics and dynamics, relatively simple estimates for train vibrations are derived. It is shown how these estimates could be used to develop more rational design criteria.

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Major Role of Landform and Soil Profile in Earthquake Damage Prediction"
Seminar Monday, Sept 21, 2009, 12:00 – 12:45 PM, CSEB-B17
Shoichi Nakai, Dr.Eng. Dept. of Urban Environment Systems, Chiba University, Japan

It is well known that the surface soil condition and micro topography influence the seismic intensity of the ground and hence impact structural damage to the civil infrastructure during earthquakes. This seminar will begin with an overview of damage occurring in recent earthquakes in Japan, followed by an introduction to earthquake damage prediction efforts. The damage predictions conducted by a local government of Chiba prefecture, a art of the Tokyo metropolitan area, will be reviewed with an emphasis on the importance of local landform and soil profile to this work. In the final part of the seminar, how the theory of elastic wave propagation, classification and optimazation can contribute to damage predictions will be reviewed.
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“Free Surface Flow Modeling with GPU-SPHysics"
Seminar Monday, Sept 14, 2009, 12:00 – 12:45 PM, CSEB-B17
Professor Robert A. Dalrymple Willard & Lillian Hackerman Professor of Civil Engineering, Johns Hopkins University

Water waves and other free surface flows are readily modeled with Smoothed Particle Hydrodynamics (SPH). This talk will discuss SPH and its application for breaking waves, levee/dam failures, and waves around pilings. GPU-SPHysics is an implement of the open source code SPHysics on the Graphics Processing Unit (GPU), which offers commodity supercomputing at low cost.
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