Civil and Environmental Engineering Faculty Research and PublicationsCopyright (c) 2016 Marquette University All rights reserved.
http://epublications.marquette.edu/civengin_fac
Recent documents in Civil and Environmental Engineering Faculty Research and Publicationsen-usSun, 26 Jun 2016 01:35:46 PDT3600End Mass Effects on the Frequency Response of Cantilevers: Analytical Results
http://epublications.marquette.edu/civengin_fac/123
http://epublications.marquette.edu/civengin_fac/123Fri, 24 Jun 2016 09:35:54 PDTStephen M. HeinrichUsing Fibre-reinforced Polymer (FRP) Composites in Bridge Construction and Monitoring Their Performance: An Overview
http://epublications.marquette.edu/civengin_fac/122
http://epublications.marquette.edu/civengin_fac/122Mon, 20 Jun 2016 07:41:44 PDTBaolin WanConditional Spectra [encyclopedia entry]
http://epublications.marquette.edu/civengin_fac/121
http://epublications.marquette.edu/civengin_fac/121Fri, 17 Jun 2016 13:17:48 PDTTing Lin et al.Development of Low Cost Piezoresistive Organic Cantilever Resonator
http://epublications.marquette.edu/civengin_fac/120
http://epublications.marquette.edu/civengin_fac/120Wed, 08 Jun 2016 10:23:40 PDTD. Thuau et al.Development of an Aquaponics Research Program
http://epublications.marquette.edu/civengin_fac/119
http://epublications.marquette.edu/civengin_fac/119Wed, 08 Jun 2016 09:53:24 PDTRichard W. Marklin Jr. et al.Comparative Evaluation of Operating Life for Phosphate-Specific Ion Exchange Resins
http://epublications.marquette.edu/civengin_fac/118
http://epublications.marquette.edu/civengin_fac/118Wed, 08 Jun 2016 09:39:17 PDTBrooke K. MayerProbabilistic Sea-Level Rise Hazard Analysis
http://epublications.marquette.edu/civengin_fac/117
http://epublications.marquette.edu/civengin_fac/117Wed, 08 Jun 2016 09:25:08 PDT
This paper proposes a framework termed Probabilistic Sea-Level Rise Hazard Analysis (PSLRHA), to integrate the sea-level rise knowledge of current climate change scientific communities for informed engineering and policy decisions that affect coastal infrastructure, populations, and ecosystems. PSLRHA combines probabilities of all emission scenarios with predictions of the resulting sea-level rise over time, in order to compute sea-level rise hazard. PSLRHA also incorporates uncertainties in those sea-level rise predictions, by considering multiple Sea-Level Rise Prediction Models (SLRPMs). The output of the PSLRHA framework could be a Global Sea-Level Rise Hazard Map (GSLRHM) that can be used for Performance- Based Sea-Level Rise Engineering (PBSLRE).
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Ting LinConditional Spectrum Computation Incorporating Multiple Causal Earthquakes and Ground‐Motion Prediction Models
http://epublications.marquette.edu/civengin_fac/116
http://epublications.marquette.edu/civengin_fac/116Mon, 06 Jun 2016 07:05:45 PDT
The Conditional Spectrum (CS) is a target spectrum (with conditional mean and conditional standard deviation) that links seismic hazard information with ground motion selection for nonlinear dynamic analysis. Probabilistic seismic hazard analysis (PSHA) estimates the ground motion hazard by incorporating the aleatory uncertainties in all earthquake scenarios and resulting ground motions as well as the epistemic uncertainties in ground motion prediction models (GMPMs) and seismic source models. Typical CS calculations to date are produced for a single earthquake scenario using a single GMPM, but more precise use requires consideration of at least multiple causal earthquakes and multiple GMPMs that are often considered in a PSHA computation. This paper presents the mathematics underlying these more precise CS calculations. Despite requiring more effort to compute than approximate calculations using a single causal earthquake and GMPM, the proposed approach produces an exact output that has a theoretical basis. To demonstrate the results of this approach and compare the exact and approximate calculations, several example calculations are performed for real sites in the western U.S. (WUS). The results also provide some insights regarding the circumstances under which approximate results are likely to closely match more exact results. To facilitate these more precise calculations for real applications, the exact CS calculations can now be performed for real sites in the U.S. using new deaggregation features in the U.S. Geological Survey hazard mapping tools. Details regarding this implementation are discussed in this paper.
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Ting Lin et al.A Computationally Efficient Ground-Motion Selection Algorithm for Matching a Target Response Spectrum Mean and Variance
http://epublications.marquette.edu/civengin_fac/115
http://epublications.marquette.edu/civengin_fac/115Fri, 03 Jun 2016 10:14:18 PDT
Dynamic structural analysis often requires the selection of input ground motions with a target mean response spectrum. The variance of the target response spectrum is usually ignored or accounted for in an ad hoc manner, which can bias the structural response estimates. This manuscript proposes a computationally efficient and theoretically consistent algorithm to select ground motions that match the target response spectrum mean and variance. The selection algorithm probabilistically generates multiple response spectra from a target distribution, and then selects recorded ground motions whose response spectra individually match the simulated response spectra. A greedy optimization technique further improves the match between the target and the sample means and variances. The proposed algorithm is used to select ground motions for the analysis of sample structures in order to assess the impact of considering ground-motion variance on the structural response estimates. The implications for code-based design and performance-based earthquake engineering are discussed.
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Nirmal Jayaram et al.A Multi-Modal Continuous-Systems Model of a Novel High-Q Disk Resonator in a Viscous Liquid
http://epublications.marquette.edu/civengin_fac/114
http://epublications.marquette.edu/civengin_fac/114Tue, 29 Mar 2016 11:41:00 PDTMohamad S. Sotoudegan et al.Finite Element Analysis of FRP Debonding Failure at the Tip of Flexural/Shear Crack in Concrete Beam
http://epublications.marquette.edu/civengin_fac/113
http://epublications.marquette.edu/civengin_fac/113Tue, 29 Mar 2016 11:15:35 PDT
One of the most common failure modes of strengthened RC beams with externally bonded FRP is intermediate crack (IC) debonding of FRP initiated at the tip of flexural/shear cracks. This study presents a method, using extended finite element method (XFEM), to model IC debonding in an FRP-strengthened concrete beam. In XFEM, as soon as a damage initiation criterion is reached in an element, additional degrees of element freedom are added to model crack initiation. Crack propagation is then modeled using fracture energy criterion. This method can be used to simulate debonding failure along an arbitrary, solution-dependent path without the requirement of remeshing. The numerical results are validated against experimental data and good agreement is found. A sensitivity analysis is conducted to study the effects of damage band properties and geometry on FRP debonding failure. This verifies that shear strength and critical mode II fracture energy are the parameters most affecting the FRP debonding model when the crack tip is subjected to mode II loading.
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Tayyebeh Mohammadi et al.Validation of Earthquake Simulations and Their Effects on Tall Buildings Considering Spectral Shape and Duration
http://epublications.marquette.edu/civengin_fac/112
http://epublications.marquette.edu/civengin_fac/112Fri, 18 Mar 2016 13:09:59 PDTTing Lin et al.Seismic Response of a Tall Building to Recorded and Simulated Ground Motions
http://epublications.marquette.edu/civengin_fac/111
http://epublications.marquette.edu/civengin_fac/111Fri, 18 Mar 2016 12:15:57 PDT
Seismological modeling technologies are advancing to the stage of enabling fundamental simulation of earthquake fault ruptures, which offer new opportunities to simulate extreme ground motions for collapse safety assessment and earthquake scenarios for community resilience studies. With the goal toward establishing the reliability of simulated ground motions for performance-based engineering, this paper examines the response of a 20-story concrete moment frame building analyzed by nonlinear dynamic analysis under corresponding sets of recorded and simulated ground motions. The simulated ground motions were obtained through a larger validation study via the Southern California Earthquake Center (SCEC) Broadband Platform (BBP) that simulates magnitude 5.9 to 7.3 earthquakes. Spectral shape and significant duration are considered when selecting ground motions in the development of comparable sets of simulated and recorded ground motions. Structural response is examined at different intensity levels up to collapse, to investigate whether a statistically significant difference exists between the responses to simulated and recorded ground motions. Results indicate that responses to simulated and recorded ground motions are generally similar at intensity levels prior to observation of collapses. Collapse capacities are also in good agreement for this structure. However, when the structure was made more sensitive to effects of ground motion duration, the differences between observed collapse responses increased. Research is ongoing to illuminate reasons for the difference and whether there is a systematic bias in the results that can be traced back to the ground motion simulation techniques.
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Nenad Bijelic et al.Advancement in Ion Exchange Processes for Municipal Wastewater Nutrient Recovery
http://epublications.marquette.edu/civengin_fac/110
http://epublications.marquette.edu/civengin_fac/110Tue, 01 Mar 2016 10:16:20 PST
Interest in the recovery of nitrogen and phosphorus from wastewater has increased as it provides a way of securing nutrient supply for crops, reducing energy costs in obtaining raw nutrients, and reducing eutrophication in waterways resulting from discharge of nutrients. For mainstream recovery, alternative nutrient removal technologies such as ion exchange (IX) must be considered to concentrate the nutrients in order for recovery to be economical. Nutrients are concentrated in the regenerant of IX. Batch and column tests were conducted to optimize desorption of NH_{4}^{+} and maintain IX capacity. During batch testing with clinoptilolite for NH_{4}^{+} exchange, regeneration with 8% NaCl or 7.5% NaCl at pH=12 maintained 84% of initial IX capacity after 7 IX cycles. When operating an NH_{4}^{+} IX column treating with secondary clarifier effluent dosed with nutrients, 120 bed volumes of sample was reduced from 32 mg/l to less than 1 mg/l NH_{4}^{-}N.
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Allen T. Williams et al.Toward Higher-Order Mass Detection: Influence of an Adsorbate’s Rotational Inertia and Eccentricity on the Resonant Response of a Bernoulli-Euler Cantilever Beam
http://epublications.marquette.edu/civengin_fac/109
http://epublications.marquette.edu/civengin_fac/109Mon, 29 Feb 2016 09:08:40 PST
In this paper a new theoretical model is derived, the results of which permit a detailed examination of how the resonant characteristics of a cantilever are influenced by a particle (adsorbate) attached at an arbitrary position along the beam’s length. Unlike most previous work, the particle need not be small in mass or dimension relative to the beam, and the adsorbate’s geometric characteristics are incorporated into the model via its rotational inertia and eccentricity relative to the beam axis. For the special case in which the adsorbate’s (translational) mass is indeed small, an analytical solution is obtained for the particle-induced resonant frequency shift of an arbitrary flexural mode, including the effects of rotational inertia and eccentricity. This solution is shown to possess the exact first-order behavior in the normalized particle mass and represents a generalization of analytical solutions derived by others in earlier studies. The results suggest the potential for “higher-order” nanobeam-based mass detection methods by which the multi-mode frequency response reflects not only the adsorbate’s mass but also important geometric data related to its size, shape, or orientation (i.e., the mass distribution), thus resulting in more highly discriminatory techniques for discrete-mass sensing.
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Stephen M. Heinrich et al.The Effects of an Antimicrobial on Anaerobic Digestion Microbial Communities
http://epublications.marquette.edu/civengin_fac/108
http://epublications.marquette.edu/civengin_fac/108Tue, 16 Feb 2016 07:53:20 PST
Over two hundred metric tons of micropollutants are discharged to the environment with biosolids each year in the U.S. Of particular concern is the antimicrobial agent triclosan, which accumulates under methanogenic conditions in wastewater treatment plants. Experiments were setup to test the impacts of triclosan on methanogenic community structure and function. Microbial communities that had not been exposed to triclosan were able to adapt to triclosan at environmentally relevant levels and maintain function. However, when communities with previous exposure to triclosan were amended with triclosan at approximately four-fold current environmental levels, their community structures shifted and methane production was cut in half.
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Patrick J. McNamara et al.Pyrolysis of Wastewater Biosolids: Lab-Scale Experiments and Modeling
http://epublications.marquette.edu/civengin_fac/107
http://epublications.marquette.edu/civengin_fac/107Tue, 16 Feb 2016 07:41:33 PST
Biosolids handling is an energy intensive and expensive process. Thus, the use of beneficial end-products is strongly desired to reduce costs. Pyrolysis, the thermal decomposition of organic matter under anaerobic conditions, has potential to be a beneficial biosolids handling process. Pyrolysis results in biochar that can be used as a fertilizer, pyrolysis oil (py-oil), and pyrolysis-gas (py-gas), which can be used to fuel the pyrolysis process. Two objectives of this work were to determine i) the impact of temperature on product yields and gas energy content and ii) the enthalpy of pyrolysis of biosolids from bench-scale experiments and modeling. Increased temperatures resulted in decreased char yields, but py-oil content did not increase after 500°C. The increase in temperature resulted in higher permanent gas yields, and higher energy content in the py-gas.
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Patrick J. McNamara et al.Addressing Uncertainty in Ensemble Sea-Level Rise Predictions
http://epublications.marquette.edu/civengin_fac/106
http://epublications.marquette.edu/civengin_fac/106Mon, 07 Dec 2015 08:17:10 PST
Sea-level rise represents a looming hazard to coastal communities which remains difficult to quantify. Ensemble climate change predictions incorporate epistemic uncertainty in the climate modeling process and climate forcing scenarios help portray a range of radiative forcing changes. This study proposes a method for incorporating both model and scenario uncertainty in ensemble projections of thermosteric sea-level rise. A Markov Chain Monte Carlo algorithm is utilized to weigh the contributions of eight process-based climate models as well as the four Representative Concentration Pathways based on convergence criteria and observational data. Hazard analysis and deaggregation combine these contributions over a range of sea-level rise thresholds and quantify the relative contributions of each pathway and prediction model. The hazard maps generated suggest improved accuracy in modeling regional trends over typical ensembles. Deaggregations effectively represent model and scenario differences and the impacts of the methods used.
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Matthew A. Thomas et al.Prediction of Solder Joint Geometry
http://epublications.marquette.edu/civengin_fac/105
http://epublications.marquette.edu/civengin_fac/105Tue, 03 Nov 2015 09:59:46 PSTStephen M. HeinrichCantilever-based Resonant Microsensors with Integrated Temperature Modulation for Transient Chemical Analysis
http://epublications.marquette.edu/civengin_fac/104
http://epublications.marquette.edu/civengin_fac/104Wed, 21 Oct 2015 11:30:56 PDT
This work introduces a resonant cantilever platform with integrated temperature modulation for real-time chemical sensing. Embedded heaters allow for rapid thermal cycling of individual sensors, thereby enabling real-time transient signal analysis without the need for a microfluidic setup to switch between analyte and reference gases. Compared to traditional mass-sensitive microsensors operating in steady state, the on-chip generation of signal transients provides additional information for analyte discrimination.
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C. Carron et al.