Engineering Commons^™

Dynamic Field Test Of A Model Levee Founded On Peaty Organic Soil Using An Eccentric Mass Shaker, E. T. Reinert, S. J. Brandenberg, J. P. Stewart, R. E.S. Moss

Civil and Environmental Engineering

A dynamic field test of a model levee was performed to study the behavior of very soft and compressible peaty organic soils that commonly underlie levees in the Sacramento / San Joaquin Delta in northern California. This first-of-its-kind test applied dynamic loads to the levee/peat system using a large eccentric mass shaker mounted on the levee crest. Loads from the shaker and the inertia of the levee section are transmitted to the peaty organic soils as base shear stresses, and rotational demands that manifest as normal pressures at the embankment/peat interface. We seek to characterize the transmission of seismic energy …

Dynamic Field Test Of A Model Levee Founded On Peaty Organic Soil Using An Eccentric Mass Shaker, E. T. Reinert, S. J. Brandenberg, J. P. Stewart, R. E.S. Moss

Civil and Environmental Engineering

A dynamic field test of a model levee was performed to study the behavior of very soft and compressible peaty organic soils that commonly underlie levees in the Sacramento / San Joaquin Delta in northern California. This first-of-its-kind test applied dynamic loads to the levee/peat system using a large eccentric mass shaker mounted on the levee crest. Loads from the shaker and the inertia of the levee section are transmitted to the peaty organic soils as base shear stresses, and rotational demands that manifest as normal pressures at the embankment/peat interface. We seek to characterize the transmission of seismic energy …

Electric Currents Due To Stress-Activated Positive Hole Charge Carriers In Ice, Cary T. Keller P.E., Friedemann T. Freund, Dale P. Cruikshank

STAR Program Research Presentations

Jupiter’s satellite Europa, whose surface is composed of ice with a possible water ocean beneath, could conceivably serve as an abode for extraterrestrial life. This and other icy celestial bodies may contain organic macromolecular solid material that is produced when surface ices are exposed to ultraviolet radiation and/or electrical energy. Tidal and tectonic stresses or meteorite impacts in icy crusts may produce electrical discharges, which would provide the energy for in-situ synthesis of the organic solids. This electrical energy can be provided by positive hole charge carrier activation. Positive holes exhibit properties such as the ability to flow out of …

Model Performance Sensitivity To Objective Function During Automated Calibrations, Misgana Muleta

Civil and Environmental Engineering

Previous studies have reported limitations of the efficiency criteria commonly used in hydrology to describe goodness of model simulations. This study examined sensitivity of model performance to the objective function used during automated calibrations. Nine widely used efficiency criteria were evaluated for their effectiveness as objective function, and goodness of the model predictions were examined using 13 criteria. Two cases (Case I: Using observed streamflow data and Case II: Using simulated streamflow) were considered to accomplish objectives of the study using a widely used watershed model (SWAT) and good-quality field data from a well-monitored experimental watershed. Major findings of the …

Coseismic Tectonic Surface Deformation During The 2010 Maule, Chile, MW 8.8 Earthquake, Keith Kelson, Robert C. Witter, Andrés Tassara, Isabelle Ryder, Christian Ledezma, Robb Moss, Laurie Johnson

Civil and Environmental Engineering

Tectonic deformation from the 2010 Maule (Chile) M_w 8.8 earthquake included both uplift and subsidence along about 470 km of the central Chilean coast. In the south, deformation included as much as 3 m of uplift of the Arauco Peninsula, which produced emergent marine platforms and affected harbor infrastructure. In the central part of the deformation zone, north of Constitución, coastal subsidence drowned supratidal floodplains and caused extensive shoreline modification. In the north, coastal areas experienced either slight uplift or no detected change in land level. Also, river-channel deposition and decreased gradients suggest tectonic subsidence may have occurred in …

A Formal Bayesian Approach For Uncertainty Analysis Of A Watershed Model, Misgana K. Muleta

Civil and Environmental Engineering

Uncertainty analysis (UA) has received substantial attention in water resources during the last decade. Bayesian approaches are often preferred for UA. This study describes a formal Bayesian approach for the assessment of parameter uncertainty and predictive uncertainty using a spatially distributed hydrologic model and will demonstrate its application using data from a well monitored experimental watershed. A Markov-Chain Monte Carlo (MCMC) scheme has been used to sample posterior parameter distributions. A formal, flexible likelihood function that explicitly accounts for heteroscedasticity, temporal correlation and non-normality of simulation residuals has been used to describe closeness of the simulated and observed streamflow. Performance …

Approaches To Control Nitrate Pollution In The San Joaquin Watershed, Misgana K. Muleta, Stephen Clayton

Civil and Environmental Engineering

No abstract provided.

Evaluating Alternative Hydraulic Solutions To Limit Nutrient Contamination Of An Aquifer In Southern California, Jake M. Perry, Misgana K. Muleta

Civil and Environmental Engineering

Many small communities depend on groundwater sources for drinking water and they often use septic tanks for wastewater treatment and disposal. Nitrate and other pollutants leaking from poorly designed septic tank systems can percolate to the aquifers and alter quality of the groundwater. This study describes a groundwater model developed using Visual MODFLOW for an aquifer that is used as a water supply source for the communities of Beaumont and Cherry Valley, CA. The aquifer has been contaminated by nitrates leaking from septic tank systems. The model will assist in clarifying the extent of interactions between nitrate pollutants, percolation from …

Uncertainty Analysis And Calibration Of Swmm Using A Formal, Bayesian Methodology, Misgana K. Muleta

Civil and Environmental Engineering

Importance of uncertainty analysis (UA) to estimate the degree of reliability associated with model predictions is being understood. Consequently, literature that describes various Bayesian methods for the assessment of parameter and model predictive uncertainty has been steadily rising. Applications dealing with urban stormwater management are, however, very limited. This study demonstrates successful application of a formal Bayesian methodology for UA of the U.S. EPA Stormwater Management Model (SWMM), a widely used urban stormwater management model, and illustrates the methodology using a highly urbanized watershed in southern California. DREAM(ZS), a recently developed effective and efficient sampling algorithm, and a generalized, formal …

Discussion Of “Comparison Of Base Shears Estimated From Floor Accelerations And Column Shears”, Rakesh K. Goel

Civil and Environmental Engineering

In lieu of a provided abstract, the first paragraph is provided:

The author agrees with Dr. Pinho about difficulties associated with the use of different damping models in nonlinear dynamic analysis. However, the focus of the original manuscript was to illustrate the difference between base shear estimated from floor accelerations, denoted as inertial base shear, and base shear estimated from column shears, denoted as the structural base shear. The difference between the two base shears exists regardless of the damping model used in the nonlinear analysis. In order to illustrate this conclusion, the Los Angeles building of the original manuscript …

Scale Model Shake Table Testing Of Seismic Earth Pressures In Soft Clay, Robb Moss, R.E. Noche

Civil and Environmental Engineering

There is much uncertainty in seismic earth pressures for basement wall design and retaining wall design in clay soil. The research presented herein uses a scale model testing platform on a 1g shake table to measure the distribution and magnitude of seismic earth pressures for the prototype soil conditions of San Francisco Young Bay Mud (YBM). Similitude scaling of the dynamic soil properties, the wall dimensions, and the input time histories (among other variables) affords accurate modeling of the prototype scale wall. For basement conditions, inertial soil structure interaction (SSI) effects are included in the experiments. Care is taken to …

Improving Model Performance Using Season-Based Evaluation, Misgana Muleta

Civil and Environmental Engineering

Computer models have become vital decision-making tools in many areas of science and engineering including water resources. However, models should be properly evaluated before use to improve the likelihood of making sound decisions based on their results. The model evaluation technique practiced today in hydrology assumes that model parameters are season insensitive and attempts to identify “optimal” values that would describe watershed behavior during dry and wet seasons. This assumption could compromise accuracy of model predictions. This study demonstrates performance improvement that would be achieved when a season-based model evaluation approach is pursued. A global sensitivity analysis (SA) model has …

Use Of Post-Consumer Corrugated Fiberboard As Fine Aggregate Replacement In Controlled Low-Strength Materials, James L. Hanson, Gregory M. Stone, Nazli Yesiller

Civil and Environmental Engineering

This study was conducted to investigate the use of post-con­sumer corrugated board in controlled low-strength material (CLSM) applica­tions. Corrugated fiberboard (termed corrugate), which constitutes a significant fraction of the municipal solid waste stream in the United States (approximately one third by weight), was used as a partial replacement for fine aggregate in CLSM at aggregate replacement ratios ranging from 0 % (i.e., control) to 6 %. The corrugate was fiberized (i.e., repulped) in a blender prior to being mixed with other constituents in the CLSM. The density, air con­tent, and flow consistency of the fresh CLSM were determined, and bleeding …

The Development Of An Integrated Residential Construction Management Course, Scott D. Kelting, Eric A. Holt

Construction Management

This paper presents the recent changes to different delivery methods for a residential construction management course at a major university. The project-based course was delivered similarly to a capstone course by combining Residential Methods, Estimating, Scheduling, and Contracts into one class with one overall final project. The course introduced students to land acquisition, land development, construction services, operations, finance, marketing, and sales. Information about the course’s 14 different delivery methods and the recent changes is provided in this paper. The recent changes are based on a survey that was conducted to obtain the students’ perspectives about the course delivery methods …