Civil Engineering Commons^™

Effects Of Alternate Cementitious Materials On Compressive Strength And Environmental Impacts Of Cement Mix Designs., Mitchell R. Bush

Materials Engineering

Specific proportions of Portland cement, fly ash, and blast furnace slag cement mixtures where chosen by a ternary phase diagram to be investigated. By experimental testing and company data history fly ash was limited to not exceed 30% and contribution of Portland cement must be over 50%. Ten chosen mix designs were batched by following ASTM C305-94 and cured for twenty-eight and forty-two days, the extended cure length allows the reaction of pozzolanic material with calcium hydroxide to complete. Compressive strength testing at forty-two days yielded low strength for mix designs with 20% or less Portland cement compared to our …

Steel Angle Section Members Under Combined Axial Load And Unsymmetric Bending, Maheshchandra Rajasekharan Phanibhushan

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the outcome of an investigation into the experimental and theoretical behavior of steel angle section members under combined axial load and unsymmetric bending. Tests are conducted on a series of six angle section members provided with biaxial pinned-end boundaries about the cross-sectional non-principal axes. The end bending moments and axial load are applied in a quasi-static manner until the member load-carrying capacity is reached. The experimental load-deflection and load-strain curves are recorded. The theoretical analysis is based on a system of both elastic as well as materially nonlinear differential equations. The equations were solved using an iterative …

Plain And Steel-Reinforced Concrete Shear Walls With And Without Cfrp Retrofitting, Ali Mohammed Salih Al Aloosi

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the outcome- of a study of the behavior and strength of plain and steel-reinforced concrete shear walls with and without a window opening and Carbon Fiber-Reinforced Polymer (CFRP) retrofitting. A total of seven tests were conducted using six different shear walls. Each wall was subjected to a gradually increasing static load at one of it's top corners until the maximum load was reached. The load-deflection relations and the walls' failure patterns were observed and recorded. It was found that the window opening in the plain concrete wall reduced the wall load capacity by 18 percent. For the …

Performance Of Nevada’S Aggregates In Alkali-Aggregate Reactivity Of Portland Cement Concrete, Mohammad Shahidul Islam

UNLV Theses, Dissertations, Professional Papers, and Capstones

Alkali-aggregate reaction (AAR) is a form of distress that occurs in concrete and results in serviceability problems, cracks, spalling, and other deterioration mechanisms. There are two categories of AAR, namely, alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR). Alkali-silica reaction is one of the most recognized deleterious phenomena in concrete, and has been a major concern since its discovery in the 1940s. The reaction which occurs between reactive silica or silicates present in some aggregates and alkalis of Portland cement produces an alkali-silica gel that expands in the presence of moisture resulting in concrete cracks. ACR is also a chemical reaction …

Design And Performance Of Load Bearing Shear Walls Made From Composite Rice Straw Blocks, Kevin Robert Camann

Master's Theses

Although rice straw and other grains have been used in building since pre-history, in the past two decades, there has been a move to utilize this rapidly renewable, locally available, agricultural byproduct as part of the sustainable construction movement. Up to this point, this has been done by simply stacking up the full straw bales. Stak Block, invented by Oryzatech, Inc., is a modular, interlocking block made of a composite of rice straw and binding agent that serves as an evolution in straw construction. This study investigates the feasibility of using these Stak Blocks as a structural system. The report …

An Investigation Of Students’ Conceptual Understanding In Related Sophomore To Graduate-Level Engineering And Mechanics Courses, Devlin Montfort, Shane Brown, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Interviews were conducted with students from a sophomore-level mechanics of materials class, a sophomore/junior-level structures class, a senior-level steel design class and a graduate-level advanced steel design class to investigate students’ conceptual understanding of bending and normal stress. The graduate students generally demonstrated higher computational skill and confidence but they were not significantly different from the sophomores in terms of conceptual understanding. Interestingly, the seniors showed markedly lower confidence in their ability to solve the problems posed in the interviews. Common difficulties include a conceptual definition of stress and reasoning involving the normal stresses developed under bending.

Application Of Dynamic System Identification To Timber Bridges, S T. Peterson, D I. Mclean, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

A method of global nondestructive evaluation for identifying local damage and decay in timber beams was developed in previous analytical studies and verified experimentally using simply supported beams in the laboratory. The method employs experimental modal analysis and an algorithm that monitors changes in modal strain energy between the mode shapes of a damaged structure with respect to the undamaged structure. A simple three-girder bridge was built and tested in a laboratory to investigate the capability and limitations of the method for detecting damage in a multimember timber structure. The laboratory tests showed that the method can correctly detect and …

Efficacy Of Interactive Internet-Based Education In Structural Timber Design, Aaron B. Henson, Kenneth J. Fridley, David Pollock, C Jayne Brahler

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

While traditional teaching methods (e.g., real-time, synchronous lectures) have proven effective for training future engineers, the Internet provides an avenue to reinforce the material and augment student learning, comprehension, and retention of material. This paper presents the integration and assessment of a library of interactive instructional modules specifically for a senior-level undergraduate elective course in civil engineering. An ongoing, comprehensive assessment process was implemented in the fall 1999 semester. The results of this quantitative assessment indicate that the use of well designed and pedagogically sound Internet-based supplemental modules provide students with a better understanding of course material. However, when Internet-based …

Application Of Dynamic System Identification To Timber Beams - Part I, S T. Peterson, D I. Mclean, M D. Symans, David Pollock, W F. Cofer, R N. Emerson, Kenneth J. Fridley

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

In this first part of a two-part paper, development of a method of dynamic system identification for timber beams is presented with an analytical verification of the method using a finite-element model. A method of global nondestructive evaluation for identifying local damage and decay in timber beams is investigated in this paper. Experimental modal analysis is used in conjunction with a previously developed damage localization algorithm. The damage localization algorithm utilizes changes in modal strain energy between the mode shapes of a calibrated model, representing the undamaged state of the beam of interest, and the experimentally obtained mode shapes for …

Application Of Dynamic System Identification To Timber Beams - Part Ii, S T. Peterson, D I. Mclean, M D. Symans, David Pollock, W F. Cofer, R N. Emerson, Kenneth J. Fridley

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

In a companion paper, a method of global nondestructive evaluation (NDE) for identifying local damage and decay in timber beams was developed and verified analytically using a finite-element model of a timber beam. The previously presented method of damage localization employs experimental modal analysis and an algorithm that monitors changes in modal strain energy between the mode shapes of a damaged beam with respect to the undamaged state of the beam. In this second part of a two-part paper, experimental laboratory tests on simply supported timber beams are presented to verify the capabilities and determine the limitations of the proposed …

Governing Yield Modes For Common Bolted And Nailed Wood Connections, Brian J. Tucker, David Pollock, Kenneth J. Fridley, Jeffrey J. Peters

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Connections in wood structures are important when designing for ductility. The 1997 Uniform Building Code has taken this into consideration when designating wind and earthquake load duration factors for connections. Factors of 1.6 or 1.33 may be applied to the connection strength, depending on the type of yield mode exhibited by the connection, which may be determined from the yield limit equations supplied in the National Design Specification for Wood Construction (NDS). The NDS provides the designer with multiple tables containing capacities for various common connections. Unfortunately, yield modes are not published along with tabulated capacities. Therefore, the designer must …

Lateral Resistance Of Ring-Shank Nail Connections In Southern Pine Lumber, R D. Theilen, D A. Bender, David Pollock, S G. Winistorfer

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Ring-shank nails are used in engineered structures with lateral connection design values based on theoretically derived equations which were validated only for common nails. The goal of this study was to quantify the input parameters and lateral connection strength of several types of ring-shank nails in Southern Pine lumber and critically evaluate the applicability of the theoretical equations for ring-shank nails.

Two sizes of galvanized and ungalvanized, hardened steel ring-shank nails from two manufacturers were studied. The hardened, ring-shank nails carried significantly higher loads than the common wire nails studied. Because the current method of determining yield load does not …

Flexural Behavior Of Thermoplastic Beams With And Without Frp Reinforcement, Hilmi Coskun

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the results of an experimental and theoretical study of the flexural behavior of thermoplastic beams with and without fiber-reinforced plastic (FRP) rebars. Tests are conducted on commercially available thermoplastic beams known as Seatimber. The normal stress-strain relations of both the thermoplastic material and FRP rebars are obtained in tension and compression experimentally. These mechanical property curves are then used as part of the input for developing the theoretical moment-curvature relations using an iterative equilibrium procedure. The moment-curvature relations are in turn used for predicting the beam load-deflection curves via the central finite-difference procedure. Behavior predictions are made …

Withdrawal Strength Of Ring-Shank Nails Embedded In Southern Pine Lumber, M J. Skulteti, D A. Bender, S G. Winistorfer, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Ring-shank nails are used extensively in post-frame construction due to their superior performance, yet surprisingly little testing has been done on nail sizes above 12d. Experience in the post-frame industry suggests that published allowable design values for ring-shank nails may be overly conservative and need revision. The goal of the research reported herein was to characterize the withdrawal strength of ring-shank nails embedded in Southern Pine lumber. Three sizes ofgalvanized and ungalvanized (bright) ring-shank nails from two manufacturers were studied. Ring-shank nails had approximately twice the withdrawal resistance of smooth-shank nails of the same diameter. Galvanizing slightly reduced withdrawal strength …

Threaded-Nail Fasteners - Research And Standardization Needs, B L. Wills, S G. Winistorfer, D A. Bender, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Threaded nail fasteners are commonly used in agricultural and commercial post-frame structures, yet there has been insufficient research to fully understand the effect of threads on withdrawal and lateral load resistance. The objective of this article is to review technical information on threaded nail fasteners and to identify problems facing manufacturers, designers, and users of threaded nail fasteners for engineering applications. Recommendations are given concerning research and standardization needs.

Seismic Performance Of Confined Sill Plate Connections, Joseph M. Bracci, Rebecca F. Stromatt, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

In the aftermath of the 1994 Northridge earthquake, extensive field investigations revealed damage in wood frame construction in the form of splitting of the 2 X 4 or 2 X 6 wood sill plates along the line of anchor bolts that typically connect shear walls to the masonry or concrete foundation. Due to the severity of such brittle failures, the city of Los Angeles has recently restricted the use of 2X dimension lumber in sill plates and requires the use of 3X dimension lumber. This paper presents an experimental investigation of the performance of 2X dimension lumber sill plate connections …

Lrfd For Engineered Wood Structures - Connection Behavioral Equations, Thomas E. Mclain, Lawrence A. Soltis, David Pollock, Thomas L. Wilkinson

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

A new design specification for engineered wood structures has been proposed in load and resistance factor design (LRFD) format. This paper provides an overview of the proposed LRFD connections design criteria. The connections design provisions are, in part, calibrated from allowable stress design provisions. Major changes from historic practice, however, result from a change in behavioral equations to a theoretical base for predicting the lateral strength of connections using bolts, screws, and nails. New provisions for axial withdrawal of driven and turned fasteners, as well as combined axial and lateral loading criteria are also proposed. Safety levels were calibrated to …

An Experimental Study Of Lateral Soil Pressures And Moments On Flexible Sheet Piles, James H. Donahue

Civil & Environmental Engineering Theses & Dissertations

In order to study the effect compaction has on lateral earth pressures exerted on and bending moments in steel sheet pile bulkheads, an experimental study was undertaken which employed the placement of a non-cohesive soil at two specific densities against three model piles of varying thicknesses. The soil was placed both in a loose and a dense state and the bending strains and deflections of the sheet piles were measured at various stages of backfill. Surface loadings were then placed after completion of the backfilling to observe the effects these loads had on the bending moments. The results of the …