Construction Engineering and Management Commons^™

Dynamic Vulnerability Assessment Of Highway And Railway Bridges, Mehdi Mohseni

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Dynamic loads can cause severe damage to bridges, and lead to malfunction of transportation networks. A comprehensive understanding of the nature of the dynamic loads and the structural response of bridges can prevent undesired failures while keeping the cost-safety balance. Dissimilar to the static behavior, the dynamic response of bridges depends on several structural parameters such as material properties, damping and mode shapes. Furthermore, dynamic load characteristics can significantly change the structural response. In most cases, complexity and involvement of numerous parameters require the designer to investigate the bridge response via a massive numerical study.

This dissertation targets three main …

Applications Of Cobb-Douglas Production Function In Construction Time-Cost Analysis, Ashkan Hassani

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Cobb-Douglas Production Function was widely used in economics and productivity studies across many sectors. The function’s quantitative modeling of resource inputs and production outputs is appealing to the research domain of construction management. In this thesis we explored this function’s application in construction schedule crashing and project risk analysis related to duration of construction projects. Existing research on construction time-cost tradeoff issues rarely explore the origin of the crashing cost which is defined as the cost needed to shorten the project to the desired duration. In the existing literature crashing cost function was either assumed without much justification, or came …

In-Plane Shear Resistance Of Sustainable Structural Walls With Large Openings, Matija Radovic

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Shear walls are primary structural systems that support building against lateral loads (tornadoes and hurricanes). Even though concrete shear walls are the most efficient lateral resisting system, they are rarely used in a residential construction. The reasons for why contractors do not use concrete walls in residential construction were due to higher construction cost and slower construction paces. This study proposes building and testing residential concrete structural wall system that is energy efficient, cost competitive and structurally safe.

In order to decrease environmental impact of the residential construction process, this study proposed implementing sustainability concept while building residential structures. The …

An Analysis Of The Impacts Of Temperature Segregation On Hot Mix Asphalt, Thaddaeus A. Bode

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

This research was conducted to produce a more realistic picture of how variables are created and dealt with during hot mix asphalt (HMA) paving construction. Several paving projects across the State of Nebraska have been visited where sensing devices were used to test how the selected variables contribute to temperature differentials. These variables include density, moisture content within the asphalt, material surface temperature, internal temperature, wind speed, haul time, and equipment type. Areas of high temperature differentials are identified using an infrared camera whose usefulness was initially confirmed with a penetrating thermometer. A non-nuclear density device was also used to …

Efficient Prestressed Concrete–Steel Composite Girder For Medium-Span Bridges, Yaohua Deng

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

In this dissertation, a new Prestressed Concrete-Steel Composite (PCSC) girder system is introduced. The PCSC girder is composed of a lightweight W-shape steel section with shear studs on its top and bottom flanges to achieve composite action with the pretensioned concrete bottom flange and the cast-in-place concrete deck. The PCSC girder is lightweight, economical, durable and easy to fabricate. To prove its feasibility and potential, this study is to investigate design and fabrication issues associated with the PCSC girder. A service design procedure is proposed using Age-adjusted Elasticity Modulus Method (AEMM) to evaluate the time-dependent stresses and strains in the …

Curriculum Development For Recession Displaced Workers In Green Construction Industries, John Earl Killingsworth

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

More than 8 million U.S. jobs were lost during ‘The Great Recession’, pushing unemployment from 4.4% in 2007 to 10.2% in 2009. Nearly half of all job losses occurred among lower-skilled workers in construction and manufacturing industries. During this same period, however, jobs in energy efficiency and renewable energy industries grew an unprecedented 9%. As part of a $4.8M grant from the U.S. Department of Labor, the University of Nebraska began development of a workforce transition program to ‘retool’ recession displaced workers for career opportunities in new and emerging green industries. To date, the knowledge, skills, and abilities (KSAs) of …

Efficient Precast/Prestressed Floor System For Building Construction, Eliya E. A. Henin

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Precast floor systems provide a rapidly constructed solution to multi-story buildings that is economical, high quality, fire-resistant, and with excellent deflection and vibration characteristics. Conventional precast concrete floor system cannot compete with cast-in-place post tensioning flat slab floor systems when high span-to-depth ratio and flat soffit are required. This is due to the significant depth of standard precast beams, and use of column corbels and beam ledges. This research presents the development of a new precast concrete floor system that eliminates the limitations of conventional precast floor system and provides a competitive precast alternative to cast-in-place flat slab floor systems. …

A Case-Crossover Study Of Laceration Injuries In Pork Processing, Lina Lander, Gary Sorock, Terry L. Stentz, Lynette Smith, Murray Mittleman, Melissa J. Perry

Department of Construction Engineering and Management: Faculty Publications

Objectives— The authors estimated the associations between transient risk factors and laceration injuries in workers at two meatpacking plants in the Midwest.

Methods— The case-crossover design was used to collect within-subject transient work task and personal-level exposure information. RRs of laceration injuries were estimated by comparing exposures during the ‘hazard’ period (just before the laceration injury) with exposures in the ‘control’ period (the previous workweek). Stratified analyses were utilized to estimate the effects of gender, ethnicity, training and the number of adjacent coworkers on each transient risk factor.

Results— The authors interviewed 295 meatpacking workers with laceration injuries (mean age …

Determining A Community Retrofit Strategy For The Aging Housing Stock Using Utility And Assessor Data, Nathan A. Barry

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Residential buildings account for about 21.5% of the nation’s primary energy consumption and carbon emissions, and about 38% of electricity use. The housing stock in the United States consists of over 128 million residences with over 60% being constructed prior to 1979 when building codes and regulations began standardizing building practices. Seeking an opportunity to understand and reduce consumption, the scientific community developed a number of model-driven auditing software. While these computer models have been successful in predicting usage patterns in newer residential structures, they have been inaccurate in predicting and analyzing energy use in aging housing stock, predominantly homes …

Seamless Bridge And Roadway System For The U.S. Practice, Nima Ala

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Expansion joints are one of the main causes for high maintenance costs in bridges. The search for ideal expansion joints has proven fruitless. That is why it has been said that “the best joint is no joint”. A seamless bridge system is envisioned that results in bridges with long service lives by eliminating the joints over the entire length of the bridge, approach slab and a segment of the roadway called transition. All bridge thermal movements are dissipated to zero in the transition. The system is similar to a system developed in Australia but modifications had to be made to …

Effectiveness Study Of Non-Nuclear Gauge For Hot Mix Asphalt (Hma) Pavement Construction, Ziqing Zhuang

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Density is an important measure for hot-mix asphalt (HMA) pavement quality control. Traditionally, the nuclear gauge method is widely used in pavement density testing. However, some disadvantages of nuclear gauges (such as the handling, storage, and transportation of radioactive materials) have created the need of non-nuclear technology. This thesis evaluated the Pavement Quality Indicator (PQI) model 301, which was promised to be more efficient than the nuclear method. The PQI utilizes many electrical impedance principles by using the current going through the pavement to determine its density and moisture content. Test data were collected in the field during pavements, and …

Effectiveness Study On Temporary Pavement Marking Removals Methods, Koudous Kabassi

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

This study was conducted to identify effective temporary marking removal methods and procedures on concrete and asphalt pavements. Pavement markings provide guidance to road travelers and can lead to accidents when not properly removed. Current state guidelines on removal do not provide clear and objective methods of measurement. After testing the most common removal methods, this research concluded that removing markings by chemical was not only cost and results-oriented effective compared to other methods, but it was also safe to the environment and road users. Finally, a baseline of measurements was developed for this project, along with the feasibility of …

The Aerodynamic Behaviour Of Respiratory Aerosols, Kristin K. Grosskopf

Department of Construction Engineering and Management: Faculty Publications

Hospital acquired infections (HAIs) claim on average 90,000 lives each year in the U.S., nearly three times the number of annual highway deaths. Although fewer than 15% of HAIs are directly attributable to airborne transmission, more than a third may be caused by surface microbes aerosolized by the movement of air from building systems, people and equipment. As a result, a study was devised to use a synthetic respiratory aerosol to track the movement airborne contagion with respect to various environmental conditions in a healthcare environment.

Complex Engineering System Learning Through Study Of Engineering Failure Cases Using 3d Animations, Zhigang Shen, Yimin Zhu

Department of Construction Engineering and Management: Faculty Publications

Complex engineering systems often require dynamic coordination of multidisciplinary teams with conflicting objectives. Failing to understand the complex relationships among the conflicting objectives may result in serious engineering failures. In engineering education, one of the challenges in teaching complex systems is the lack of effective tools to demonstrate system dynamics, especially spatial-temporal relationships in the system. The described project in this paper is supported by grants from Engineering Education program of the National Science Foundation. In the project civil/construction engineering cases are used as the context to test the proposed new teaching/learning tool on the subject and to demonstrate the …

Limited Scope Permitting For Time-Sensitive Project Delivery Systems, Wayne Jensen, Bruce Fischer, Zhigang Shen

Department of Construction Engineering and Management: Faculty Publications

Delivery of construction projects in the United States has traditionally been based upon the design-bid-build system. TIlis system has been used to create numerous impressive structures, but it often proves expensive and usually requires considerable time, because design, permitting and construction are accomplished in sequential order and do not overlap. Several alternatives to the traditional system have been developed, many of which fall under the classification of time-sensitive project delivery systems. The most commonly used time-sensitive project delivery systems are phased and fast-track construction (FaZio, Moselhi, Theberge & Revay 1988a). Figure 1 illustrates some of the major differences between traditional …

A Building Lca Case Study Using Autodesk Ecotect And Bim Model, Endong Wang, Zhigang Shen, Charles Barryman

Department of Construction Engineering and Management: Faculty Publications

The main objective of this study is to evaluate the potential of utilizing building information model (BIM) to perform whole building Life Cycle Analysis (LCA). The research question addressed was how life cycle performance of a building was affected quantitatively by design configurations. Life cycle energy consumption and CO₂ emission of a university building in the Midwest was calculated using Autodesk® Ecotect and BIM model. The study compared life cycle performance, i.e., CO₂ emissions and energy consumptions, among different design configurations, as well as their distributions in the stages of the building’s life time. Sensitivity analysis was performed …

Effects Of Warm-Mix Asphalt Additives On Asphalt Mixture Characteristics And Pavement Performance, Jun Zhang

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The primary objective of this research is to evaluate the feasibility of several WMA mixtures as potential asphalt paving mixtures for Nebraska pavements. To that end, three well-known WMA additives (i.e., Sasobit, Evotherm, and Advera synthetic zeolite) were evaluated. For a more realistic evaluation of the WMA approaches, trial pavement sections of the WMA mixtures and their HMA counterparts were implemented in Antelope County, Nebraska. More than one ton of field-mixed loose mixtures were collected at the time of paving and were transported to the NDOR and UNL laboratories to conduct comprehensive laboratory evaluations and pavement performance predictions of the …

Affordable Lightweight High Performance Concrete (Alwhpc): Expanding The Envelope Of Concrete Mix Design, Kevin J. Simons

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

One way to reduce excess material would be to lighten the load on a structure with the use of affordable lightweight high performance concrete (ALWHPC). Most or all lightweight high performance concrete mixes used today include lightweight aggregates as the coarse aggregate and sand for the fine aggregate. ALWHPC mix designs contain all lightweight aggregates and cementitious materials that are readily available throughout the United States. Instead of 115 – 120 pcf, ALWHPC mix designs range from 88 – 100 pcf and strengths from 2,700 – 8,700 psi compressive strength. This research will explore the use of local lightweight aggregates …

Quantitative Evaluation Of The Bim-Assisted Construction Detailed Cost Estimates, Zhigang Shen, Raja R. A. Issa

Department of Construction Engineering and Management: Faculty Publications

The increased interest in using Building Information Modeling (BIM) in detailed construction cost estimates calls for methodologies to evaluate the effectiveness of BIM-Assisted Detailed Estimating (BADE) tools in generating detailed construction cost estimates. The focus of this study is on developing a quantified evaluation method to measure the impact of these BADE tools. Further, in order to understand the cognitive details of the estimator, this study also tested and evaluated the impact of the visualization factor and the compound impact of the visualization factor and aggregated calculation factor on the construction cost-estimating process. Two types of BADE tools were tested …

Measuring Performance Of Innovative Pavement Features, Wayne Jensen, Zhigang Shen, Cody Kluver

Department of Construction Engineering and Management: Faculty Publications

The Nebraska Department of Roads (NDOR) conducts annual examinations of the state's interstate and federal highway pavements. During these examinations, numerous indicators of pavement performance are measured directly or compiled from parameters recorded by a vehicle passing over the pavement section. Parameters are documented and analyzed for each one-tenth mile pavement segment. Seven sections where innovative features have been incorporated into the pavement were selected by the NDOR for comparison to nearby conventional pavement sections. This study used various parameters recorded by the NDOR as well as field observations to compare the performance of seven pairs of pavement sections. Each …

Development Of High Performance Precast/Prestressed Bridge Girders, Amin K. Akhnoukh

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Demand continues to increase for bridges with long spans and shallow depths. Due to safety concerns, four-span overpasses are being replaced with two span overpasses to avoid placement of piers near the highway shoulders. In the meantime, the bridge profile is restricted due to existing businesses nearby. Thus, nearly the same superstructure depth must be used for double the span length. This dissertation focuses on topics aiming at providing precast prestressed concrete girders with the shallowest possible depth for a given span. It forms parts of larger projects conducted by the University of Nebraska for the Nebraska Department of Roads …

Semantic 3d Cad And Its Applications In Construction Industry — An Outlook Of Construction Data Visualization, Zhigang Shen, Raja R. A. Issa, Linxia Gu

Department of Construction Engineering and Management: Faculty Publications

In response to the need of using electronic design data directly in construction management applications, many CAD developers have started implementing semantic data models in their CAD products using industry foundation classes (IFCs). While helpful, these semantic CAD applications have limitations when used in actual construction practices. The case studies in the thesis indicated that: 1) the semantics of the current data model (IFC as an example) is not rich enough to cover the richer details of the real trade practices; 2) the current implementation of the semantic data model lacks the mechanism to provide multiple trades views at various …

Course Portfolio For Arch333/Cnst305: Building Environmental Technical Systems, Tim Wentz

UNL Faculty Course Portfolios

Due to the critical nature of team-based learning in this course, I propose to study the learning aspects of team-based learning, as I envision it in this course. Not having formally investigated this issue previously, I am left with a sense that some teams perform much better than other teams. I am looking for those criteria that separate the good teams from underperforming teams. Some of the issues that occur to me as I start this process include the following: - Team size - Academic diversity - Discipline diversity - Gender diversity - Geographic diversity How students best learn in …

A Trade Construction Knowledge Module To Enable Use Of Design Component Data In Project Management, Zhigang Shen, Raja R. A. Issa, William J. O'Brien, Ian Flood

Department of Construction Engineering and Management: Faculty Publications

The complexity, tight budget, and dynamic market of today's construction project require the seamless integration of both design and construction data, However, despite the availability of both digital design tools (various CAD applications) and digital project management tools (such as schedule software and construction management software), design data has to still be entered manually into construction applications. In order to close this gap, CAD applications widely used in AEC industries are evolving toward providing the product data within the CAD package itself, in addition to the existing graphic-oriented data. While useful, those new data-driven CAD applications are largely design-oriented and …

A Model For Integrating Construction Design And Schedule Data, Zhigang Shen, Raja R. A. Issa, William O'Brien

Department of Construction Engineering and Management: Faculty Publications

The difficulty of timely retrieval of useful information from heterogeneous data sources is a major cause of low productivity in the construction industry. The goal of this research is to provide a new methodology to handle the data-heterogeneity problems encountered in a construction project. This research proposes a tree-structured product model, which binds design knowledge, cost data and schedule data together, as a feasible solution for the data integration problem in construction projects. The methodology uses the knowledge representation of construction projects based on an ontology. Metadata are used to describe the conceptual structure of the project knowledge. The concept …