Engineering Commons^™

Collaborative Research: An Integrated Microstructure-Based Approach To Property Prediction For Cement-Based Materials, Eric N. Landis

University of Maine Office of Research Administration: Grant Reports

The project is a collaborative effort between the research groups at the University of Maine and the University of California, Davis. It represents a convergence of 3D micro-structural imaging with discrete element computational modeling to address the need for quantitative links between salient micro-structural properties and bulk material performance. High-resolution 3D images of material microstructure will be produced using x-ray microtomography (XMT). These images will be used to examine the micromechanical response of cement composites to mechanical loading and drying shrinkage. 3D deformation fields and internal crack distributions will be measured at selected loading stages and correlated with the spatial …

Durability And Fatigue Behavior Of Cip Concrete Connections For Accelerated Bridge Construction, Peng Zhu

Doctoral Dissertations

Continuous longitudinal and transverse U-bar joint connections between flanges of the decked bulb-Ts (DBTs) or between precast panels for accelerated bridge construction are investigated. The procedure for selecting durable closure pour (CP) materials for the connections is discussed firstly. The accelerated construction is quantified as two categories: overnight cure and 7-day cure of CP materials. Candidate materials are selected first based on literature review as well as tests of compressive strength and flow and workability. Then, performance criteria for selecting durable CP materials for both categories are developed based on durability tests of selected candidate materials. These durability tests include …

Investigating Wood Welding Parameters Using A Prototype Welding Machine, Timothy R. Melin

Master's Theses

Understanding how different processing variables influence wood welded bonds is vital if the technique will ever be used to create engineered lumber without using adhesives. A variation of vibration welding, wood welding uses pressure and friction to bond materials together. During welding, heat causes a softening in the wood, a naturally occurring composite material. This softening leads to fiber entanglement and a bond forms upon cooling.

The goal of this research was to investigate several processing aspects of the wood welding procedure. A prototype wood welding machine, designed and fabricated from the ground up, was used to investigate the effects …

Stability Analysis Of Single And Double Steel Girders During Construction, Sean Justin Coffelt

Masters Theses

Built-up steel I-girders are very commonly used in bridge construction. Their spans are typically very long, and they are susceptible to lateral torsional buckling if not enough lateral support is provided. This thesis includes guidelines for preventing lateral torsional buckling of steel I-girders under dead and wind load, accompanied with finite element analysis of double girder systems. The first portion includes capacity envelopes for single girders with single and double symmetric cross sections under various loading conditions and boundary conditions for double and single symmetric cross sections with double girders subjected to dead loads only. The second portion is dedicated …

Seismic Analysis Of Integral Abutment Bridges Considering Soil Structure Interaction, Reza Vasheghani Farahani

Masters Theses

Integral abutment bridges are jointless bridges in which the deck is continuous and connected monolithically with the abutment walls supported typically by a single row of piles. This thesis focuses on the effects of two major parameters on the seismic behavior of an integral abutment bridge in Tennessee by considering soil-structure interaction around the piles and in back of the abutments: (1) clay stiffness (medium vs. hard) around the piles, and (2) level of sand compaction (loose vs. dense) of the abutment wall backfilling. Modal and nonlinear time history analyses are performed on a three dimensional detailed bridge model using …

Product Technical Information, Steel Stud Manufacturers Association

CCFSS Library (1939 - present)

No abstract provided.

Cold-Formed Steel Framing Seismic Design Optimization Phase 1a: Seismic Equivalency Parameter Evaluation, American Iron And Steel Institute

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

Cfsei Educating North American Practitioners In Principles Of Cfs Framing Design, W. D. Allen

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Educating North American structural engi neers in the principles of cold-formed steel (CFS) design in general, and about CFS framing in particular, has a unique set of challenges. The undergraduate curri cula virtually ignore the subjects, and only a handful of graduate programs address the issue. Several industry associations have existed for engineers, but none specialize in CFS framing. Several organizations existed in the co ld-formed steel framing marketplace, but none were set up to accommodate engi neers. This paper will review the formation, development, growth, and maturation of one such education- and engineer-focused organization within the framework of the …

A Life-Cycle Assessment Of Cold-Formed Steel Enclosures Verses Alternative Enclosures In Commerical Buildings, K. J. Van, L. Xu

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

In North America, the operation of buildings accounts for approximately one third of the total energy use and greenhouse gas emissions each year. Over the life of a building, the total energy use is a combination of the embodied energy in the building materials and the operating energy of the building. Building enclosures (walls and roofs) have a huge impact on both the embodied energy and the operating energy of buildings. Historically, steel has been blacklisted as a material with a high embodied energy. This has led to a misconception that steel enclosures use significantly more energy than other enclosure …

Behavior And Design Of Axially Compressed Sheathed Wall Studs, L. C. M. Vieira Jr., B. W. Schafer

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The objective of this paper is to summarize efforts in a multi year project dedicated to developing a reliable design method for cold - formed steel wall studs that rely on sheathing for bracing. Testing on single columns with sheathing, and full - scale walls with sheathin g, are summarized. Particular emphasis is placed on the observed limit states given the different sheathing conditions. The sheathing supplies beneficial restraint to the wall studs and the stiffness of this sheathing - based restraint is characterized exper imentally and analytically. A unique application of the Direct Strength Method of design is explored …

Cross-Aisle Stiffness Tests On Rack Upright Frames, S. R. Sajja, R. G. Beale, M. H. R. Godley

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The US Rack Manufacturers Institution (RMI) code uses a theoretical formula derived by Timoshenko and the new Eurocode EN15512 requires testing. There is a considerable difference in the stiffn ess values determined by two approaches. This paper describes the experiments conducted on 80 full sized upright frames at Oxford Brookes University varying upright size, number of panels in the frame, aspect ratio of the panel (panel length/depth), restraints at the intermediate nodes of the frame, loading pattern, lacing pattern (channels back to back or front to front) and bolt tightness. The experimental data reported can be used in proposing revised …

Direct Strength Design Of Cold-Formed C-Sections For Shear, Cao Hung Pham, Gregory J. Hancock

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The Direct Strength Method (DSM) rece ntly included in the North American Specification and Australian/New Zealand Standard AS/NZS 4600:2005 gives design rules for compression and bending. No rules are presente d at this stage for shear. Two series of tests on C-section can be used to develop and calibrate rules for design in shear. These are the University of Missouri Rolla tests of the 1970’s and recent tests on high strength C-sections at the University of Sydney. Both series of tests use a similar test rig altho ugh different levels of tension field action have been observed. Two features research …

Experimental Evaluation Of A Vehicular Access Door Subjected To Hurricane Force Wind Pressures, Tian Gao, Christopher D. Moen

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper describes an experimental study of a rolling sheet door under uniform positive and negative pressure, i.e. wind pushing the door into the building and wind suction pulling the door out of the building. Rolling sheet vehicular access doors are a commonly provided feature in metal building systems. The edges of the door slide freely during regular usage in tracks connected to cold-formed steel jambs. During an extreme wind event, the door engages the jambs with wind locks distributed along both vertical edges of the door to prevent excessive out-of-plane deformation. The goal of the study was to measure …

Direct Strength Design Of Cold-Formed C-Sections In Combined Bending And Shear, Cao Hung Pham, Gregory J. Hancock

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The paper describes a research program including tests on both plain C- and SupaCee ® purlin sections in combined bending and shear, and bending only. The high strength SupaCee ® profile steel sections contain additional return lips and web stiffeners which enhance the bending and shear capacity of the sections. They are used widely in Austra lia as purlins in roof and wall systems. The tests were performed at the University of Sydney with and without straps on the flange and thus allowed distortional buckling in the latter case. Design methods for these sections are normally specified in the Australian/New …

Lateral Torsional Instability Of Single Channels Restrained By Angle Cleats, G. M. Bukasa, M. Dundu Masce

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

A series of experiments on the lateral tors ional instability of single channels is presented. The channels are restrained by a purlin – angle cleat connection and subjected to a two point loading system in order to simulate a distributed load. Failure of the channels occurred by local buckling of the compression zone of the flange and web and lateral torsional buckling of the channels between points of lateral support. Tests have shown the purlin–angle cleat connection to be capable of restraining the frames from failing due to lateral-torsional buckling. This eliminates the idea of having fly-bracings, which is normally …

On The Direct Strength Design Of Continuous Cold-Formed Steel Beams, Cilmar Basaglia, Dinar Camotim

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The work reported in this paper concerns an ongoing investigation aimed at developing an efficient methodology to design continuous cold-formed steel beams failing in modes that combine local, distortional and global features. At this stage, it is intended to assess how accurately can the load-carrying capacity of lipped channel continuous (two and three-span) beams subjected to non-uniform bending be predicted by means of the current Direct Strength Method (DSM) design curves. “Exact” ultimate strength values yielded by geometrically and materially non-linear shell finite element analyses are compared with estimates provided by the DSM equations and, on the basis of this …

Extending Direct Strength Design To Cold-Formed Steel Beams With Holes, Christopher D. Moen, Benjamin W. Schafer

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The extension of the American Iron and Steel Institute’s Direct Strength Method (DSM) to cold-formed steel beams with holes is nearly in place. DSM was first introduced to th e AISI specification in 2004 as an alternative to the effective width met hod, and is widely considered a major advancement in cold-formed steel component design. In DSM, the beam elastic buckling properties for a general cross-section are obtained with a computer analysis utilizing the finite strip method. A disadvantage of the finite strip method and DSM has been that discrete holes along the member length could not be easily accounted …

Load-Carrying Capacity Estimation On Cold-Formed Thin-Walled Steel Columns With Built-Up Box Section, Yuangqi Li, Xingyou Yao, Zuyan Shen, Rongkui Ma

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The use of cold-formed thin-walled steel structural members has increased in recent years, and most of their sections are open section with only one symmetrical axis, which would likely fail by twisting and interaction with the others buckling mode, such as local buckling and distortional buckling. To improve the ultimate strength of columns, built-up box section can be used. In this paper, a series of loading capacity tests on high-strength cold- formed steel columns with built-up bo x section are presented, including 21 axially-compressed columns and 19 eccentrically-compressed columns sub- jected to bending moments about weak axis as well as …

Flexural And Cyclic Behaviour Of Hollow And Concrete-Filled Steel Tubes, S. Arivalagan, S. Kandasamy

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper presents a study on the flexural and cyclic behaviour of concrete filled steel hollow beam sections. The specimens in-filled with normal mix concrete, fly ash concrete, quarry waste concrete and low strength concrete (Brick-bat-lime concrete) and hollow steel sections were tested. Measurements of strains and deflections were made under two-point loading. A theoretical model was also developed to predict the moment carrying capacity. The capacities of the beams were compared with the ultimate capacity obtained using the international standards EC4-1994, ACI-2002 and AISC-LRFD-1999. The result of the experimental investigation showed that the moment carrying capacity increases based on …

Theoretical Analysis Of Cold-Formed Steel Battened Double Angle Members Under Compression, W. F. Maia, J. Munaiar Neto, M. Malite

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

In Brazil, battened double angle system is one of the systems most used in light truss, however, there are not any specific studies on its behavior, resulting in the fact that the standard procedures do not provide subsidies for the design of this section. Moreover, cold-formed steel si mple angles under compression, mostly with slender legs, have an interesting structural behavior compared to other cold-formed steel shapes. Two critical modes are observed in the elastic stability analysis: (i) global flexural mode in the case of longer members and (ii) a coincident local-plate/global flexural-torsional mode, which is critical for shorter members. …

Cyclic Elastoplastic Large Displacement Analysis Of Cold-Formed Steel Box Columns Under Combined Action Of Axial And Bidirectional Lateral Loading, Iraj H. P. Mamaghani, Saman Montazeri

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper deals with the cyclic elastoplastic large displacement analysis of cold-formed steel box columns under combined action of axial and bidirectional lateral loading. Cold-formed steel box columns are very useful in highway bridge pier construction as they offer flexible space requirement and provide speedy construction. Behavior of cold-formed steel box columns under earthquake-induced loads is rather complicated as earthquakes occur in an oblique direction. However, modern seismic design philosophies have been based on the behavior of structures under independent actions of uni-directional loading in orthogonal directions. In this study, inelastic cyclic behavior of steel columns subjected to constant axial …

Test And Finite Element Analysis On Distortional Buckling Of Cold-Formed Thin-Walled Steel Lipped Channel Columns, Xingyou Yao, Yanli Guo, Zhiguang Huang

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

High-strength cold-formed thin-walled steel sections have been widely used in the recent several years. However, distortional buckli ng or interaction between it and local buckling can occur for high strength cold-formed thin- walled steel members. This paper desc ribes a series of compression tests performed on lipped channel section columns with V-shape intermediate stiffener in the web and flanges fabricated from cold-formed high strength steel of thickness 0.48 and 0.6mm with nominal yield stress 550MPa. The lipped channel sections were tested to failure with both ends of the columns fixed. The test results of 16 specimens show that the local …

Impact Of Corner Radius On Cold-Formed Steel Member Strength, V. Zeinoddini, B. W. Schafer

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The objectives of this paper are to expl ore (a) how corners of cold-formed steel members are included or ignored in current design methods, and (b) the effectiveness of recent proposals for modifying the strength prediction for local buckling to account for corners. The imp act of round corners is examined on the behavior and strength of isolated elements and on full members using material and geometric nonlinear collapse analysis with shell finite elements in ABAQUS. Comparisons between the available methods and the nonlinear finite element analysis are completed to explore the regimes in which the methods are accurate, as …

Evaluating The Lrfd Factor For Cold-Formed Steel Compression Members, Karthik Ganesan, Christopher D. Moen

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper summarizes recent work to determine if the LRFD resistance factor for cold-formed steel compression member s can be increased above its current value of φ c =0.85. An experimental database of 675 concentrically loaded columns with plain and lipped C-sections, plain and lipped Z-sections, hat sections and angle sections, including members with holes was compiled. The predicted strength of each specimen was calculated with the AISI-S100-07 Main Specification and Direct Strength Method (DSM). Test-to-predicted strength statistics were employed with the first order second moment reliability approach in AISI-S100-07 Chapter F to calculate the resistance factors. The observed trends …

Experimental Investigation Of Optimized Cold-Formed Steel Compression Members, D. J. Klingshirn, E. A. Sumner, N. A. Rahman

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

In the past, standard C - shaped metal studs have been the only option for designers and contractors when selecting a cross section for load bearing compression members. T he sigma shaped section has recently emerged as an alternative to the C - section. The sigma shaped section is very similar to the C - shape, with the exception of having an intermediate web return and complex stiffeners. The experimental results of concentric axial compression tests of fifty - eight sigma shaped members are reported. Specimen s were tested at various lengths to force global, distortional, and local buckling failure …

Buckling Analysis Of Cold-Formed Steel Members With General Boundary Conditions Using Cufsm Conventional And Constrained Finite Strip Methods, Z. Li, B. W. Schafer

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The objective of this paper is to provide the theoretical background and illustrative examples for elastic buckling analysis of cold-formed steel members with general boundary conditions as implemented in the forthcoming update to CUFSM. CUFSM is an open source finite strip elastic stability analysis program freely distributed by the senior author. Although the finite strip method presents a general methodology, the conventional implementation (e.g. CUFSM v 3.13 or earlier) employs only simply-supported boundary conditions. In this paper, utilizing specially selected longitudinal shape functions, the conventional finite strip method is extended to general boundary conditions, including the conventional case: simply-simply supported, …

Angle Cleat Base Connections, M. Dundu, S. Maphosa

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Tests, performed on base connections fabricated from cold-formed channels and hot-rolled angle cleats, are presented in this paper. This research is part of an on- going research to develop portal frames made out of cold-formed steel. The base connections are subjected to an axial load and moment. Hot-rolled angle cleats are used to prevent premature failing of the base connections. Several loading configurations are considered and these are dependent on the eccentricity of the load. In all the tests the cold-formed channels failed by local buckling. A significant amount of bearing distortion was observed in the heavily loaded flange. The …

Arc-Spot Welds For Multi-Overlap Roof Deck Panels, N. Guenfoud, R. Tremblay, C. A. Rogers

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Roof deck construction often incorporates cold-formed steel panels that are connected to the underlying framing with the use of arc-spot welds. The welds are commonly located in areas where multiple layers of roof deck exist, such as at sidelaps or endlaps. CSA S136 restricts the use of multi-layer connections to being less than 2.5 mm thick; as well, the thickness of the supporting steel must exceed 2.5 times the aggregate thickness of the deck. In effect, the standard does not allow for the use of arc-spot welds for 18 ga (1.21 mm) and 16 ga (1.52 mm) roof deck panels. …

Cold Formed Steel Tension Members With Two And Three Staggered Bolts, D. M. Fox, R. M. Schuster

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The second edition of the North American Specification for the Design of Cold Formed Steel Structural Members was published in October of 2007 for use in Canada, Mexico, and the United States. This Specification contains two country specific a ppe ndices, namely Appendix A (ANSI/AISI S100- 07) for use in the US and Mexico and Appendix B (CSA S136- 07) for use in Canada. Both Appendix A and B require that a bolt stagger reduction factor of 0.90 be used when calculating the tearing failure strength [resistance] of a cold formed steel member in tension with staggered bolts. This 10% …

Screw Connections Subject To Tension Pull-Out And Shear Forces, R. M. Francka, R. A. Laboube

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Currently, the behavior of screw connections subject to combined tension pull- out and shear forces is not well understood. An experimental study was conducted at Missouri Un iversity of Science and Technology to better understand the relationship or interac tion between these forces. The test program evaluated four parameters that may influence the behavior of pure tension and pure shear in screw connections: the thickness of the sheet not in contact with the screw head, the ultimate strength of the steel, the ductility of the steel, and the screw diameter. Based on the behavior observed and analysis of the test …