F. Michael Bartlett's research while affiliated with The University of Western Ontario and other places
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Publications (46)
Concrete overlays are widely used to rehabilitate bridge decks. This investigation presents parametric and sensitivity analyses of the mechanical strains due to restraint of shrinkage of the overlay that may cause it to crack. The parametric analysis identifies the significant variables and the sensitivity analysis quantifies the correlations betwe...
Bridge decks are subjected to deterioration due to chloride ingress or other factors. Concrete overlays are used to replace the unsound concrete or to extend the life span of new concrete bridge decks. Overlay shrinkage is restrained by the substrate beneath leading to premature ingress of chlorides, corroding the steel reinforcement and producing...
Concrete decks are commonly rehabilitated using concrete overlays. Overlay shrinkage is restrained at the interface with the substrate. An analytical method is presented to compute the distribution of internal humidity and free shrinkage strains in the overlay and substrate for bridge decks with solid rectangular cross sections and therefore overco...
Conventional design and evaluation procedures usually classify steel through-truss bridges as single-load-path structures; however, their historic performance has demonstrated considerable structural resiliency. This paper presents a study of the Grand River Bridge, a Pratt through-truss bridge in Cayuga, Ontario, Canada, that systematically invest...
This is the first of two companion papers that analyse ten years of on-site monitoring data for the Confederation Bridge to determine the validity of the original wind speeds and wind loads predicted in 1994 when the bridge was being designed. The check of the original design values is warranted because the design wind speed at the middle of Northu...
This paper uses ten years of on-site monitoring data for the Confederation Bridge to derive wind loads and investigate whether the bridge has experienced its design wind force effects since its completion in 1997. The load effects derived using loads from the on-site monitoring data are compared to the load effects derived using loads from the 1994...
An analytical approach to compute restrained shrinkage effects on composite concrete deck – steel truss members is presented and validated using strains and deflections obtained by Brattland and Kennedy, who in 1986 tested two full-scale (11.8 m × 2.35 m in plan) composite trusses and companion drying specimens for approximately 90 d. The test-to-p...
Although structures have been built using wood and concrete for centuries, there is still very little understanding on how the two materials can act as a single hybrid system. Recent progress has been made to integrate wood-concrete systems into heavy timber post-and-beam buildings and short-span bridges. There is a paucity of literature, however,...
Current rehabilitation practices for aging, post-tensioned, voided-slab bridges typically reduce the geometric properties of the concrete cross section and so permanently increase post-tensioning stresses, change primary and secondary prestress moments, and create new primary and secondary moments because the original concrete restrains shrinkage o...
Changes in the Canadian steel industry warrant a review of the steel resistance factor in CSA Standard S16 (formerly S16.1) "Limit states design of steel structures", originally calibrated in the landmark study by Kennedy and Gad Aly in 1980. This paper presents statistical parameters for the bending, compression, and tension resistances of W, WWF,...
Improvements to Clause 12 of CAN/CSA Standard S6-88 "Design of highway bridges" required the transformation of basic findings into a form suitable for use by evaluators. The number of dead load categories was reduced, and the rating equation was simplified. Rating factors calculated using the new criteria were checked against past practice. Practic...
Changes in the Canadian steel industry warrant a review of the steel resistance factor in CSA Standard S16 (formerly S16.1) "Limit states design of steel structures", originally calibrated in the landmark study by Kennedy and Gad Aly in 1980. This paper summarizes data collected in 1999 and 2000 to determine statistical descriptions of geometric an...
Because upgrading a bridge is usually far more costly than incorporating extra capacity at the design stage, a different approach is appropriate. Clause 12 of CAN/CSA-S6-88, published in 1990, was developed specifically for evaluation. The development of Clause 12 is reviewed, as is the philosophy of varying the load factors based on how well the l...
This paper presents the rationale for increasing the resistance factor for concrete in compression in the 2004 edition of the Canadian Standards Association (CSA) standard A23.3, Design of concrete structures, from 0.60 to 0.65 and for precast concrete produced in CSA-certified plants from 0.65 to 0.70. The new values are supported by a probability...
The mean load method of the Canadian Highway Bridge Design Code is used to evaluate the shear and bending moment reliability of existing precast "type G" stringer bridges in Alberta that date from the late 1950s. The overall stringer population is categorized into distinct subpopulations using bridge-specific factors, including the degree of deteri...
Statistical parameters for the load effects and resistances of precast "type G" stringer bridges erected in Alberta since the late 1950s are presented to assist practicing engineers assessing similar bridges using the mean load method. The load effect data include unit weight data for normal weight and two lightweight concretes; traffic volumes, gr...
Solutions are presented for the design of reinforcement for a wide range of holes in steel webs. Methods are derived for situations not covered in available published literature. Both elastic and plastic solutions are given for round holes, either unreinforced or reinforced with doubler or tripler plates. Welds and web stability are considered. A s...
Bridge deck rehabilitation typically involves removal of unsound concrete and placement of an overlay to restore the original geometry of the deck. A water-proofing membrane is typically applied after three to four days of drying to extend the life of the overlay by preventing the ingress of de-icing chemicals. Shrinkage of the overlay is restraine...
Compression members in steel bridges designed before 1960 may be deficient according to current design code requirements and so require strengthening. This paper explores the response of steel wide-flange columns reinforced with new steel flange cover plates, accounting for: residual and locked-in dead-load stresses; different yield strengths of th...
The Confederation Bridge was the subject of extensive wind tunnel studies to define the response characteristics and the wind loads for design. The wind climate at the site was studied to better define the wind speeds for design of the completed structure as well as loads during construction. Both section model and full aeroelastic model techniques...
Two concrete T-beams reinforced with instrumented built-up hollow plain bars were tested to investigate the effect of flexural cracking and bond loss on the flexural and shear behavior. The beam with a flexural reinforcement ratio of 0.98% exhibited arch action due to bond failure that initiated when the applied load reached 60% of the failure load...
Mehanics-based relationships are established between bond stress bar force, slip at the unloaded end of the bar and slip along the length of plain steel reinforcing bars in pullout specimens. Two 200 mm (7.9 in.) diameter by 800 mm (31.5 in.) long pullout specimens reinforced with instrumented built-up hollow reinforcing bars were tested. Maximum p...
This paper presents the derivation and experimental validation of a mechanical model for unbonded seven-wire prestressing tendons with a single broken outer wire. The model has practical significance because corrosion of these tendons typically causes a single outer wire to fail first. The tendency for the tendon to deflect toward the broken wire c...
A mechanical model for unbonded seven-wire tendons with broken wires that accounts for the effects of interwire friction and contact forces between the tendon and surrounding concrete is derived. The model is an essential tool for predicting the response, and reliability, of unbonded posttensioned concrete structures containing corroded tendons wit...
Bond strength results from 252 plain bar pullout specimens are presented. Parameters investigated include: concrete compressive strength, bar size, bar shape, concrete cover; and bar surface roughness. All load-slip curves displayed a characteristic shape: the maximum tensile load occurred at a very small slip (∼0.01 mm) and the load then dopped as...
Testing of buildings and their components to failure under realistic wind loading is difficult under controlled conditions and presents a significant limitation in optimizing building performance. On one hand, the temporal and spatial variations of wind loads that occur in real wind storms are difficult to reproduce in a controlled fashion in full-...
The effectiveness of posted load limits in reducing annual maximum live load effects, thus enhancing bridge reliability, is investigated for 12 and 40 m simple span highway bridges. Novel analytical expressions are derived for event gross vehicle weight (GVW) distributions that account for violation of posted load restrictions, and the correspondin...
Typical rehabilitation procedures for posttensioned slab bridges involve removing concrete from the top surface of the bridge, replacing corroded reinforcement, and resurfacing with new concrete. These permanently change primary and thus secondary prestressing moments. Continuous posttensioned bridges often rely on secondary prestressing moments to...
Damage due to hurricanes and other windstorms has increased dramatically in recent years, incurring losses of life and property around the world. Funding from the Canada Foundation for Innovation and the Ontario Innovation Trust was awarded in 2004 for the “Three Little Pigs Project”, a CDN 7M (4.3 M €) facility to test full-scale houses and other...
Plain reinforcement is common in historical concrete structures now in need of rehabilitation. Little information on the bond and development of plain bars is readily available to American or Canadian rehabilitation engineers: the current codes provide no guidance. This paper provides a review of historical test data relating to bond of plain reinf...
Monte Carlo simulation is used to quantify the reliability of reinforced concrete cantilever beams without stirrups designed using ASCE 7-98 load factors with strength reduction factors given in Appendix C of ACI 318-99 and the main body of ACI 318-02. Limit states corresponding to flexural failure neglecting strain hardening of the reinforcement,...
DuraKit Shelters Inc. has developed a modular house for emergency, temporary or semi-permanent occupation that uses corrugated fibreboard as the main structural material. The houses are marketed internationally and so must resist tropical cyclone wind loadings.Two full-scale shelters, measuring 4.9m×6.1m in plan, were subjected to static forces equ...
DuraKit Shelters Inc. has developed a modular house for emergency, temporary or semipermanent occupation that uses corrugated fibreboard as the main structural material. The houses are marketed internationally and so must resist tropical cyclone wind loadings. Two full-scale shelters, measuring 4.9 m x 6.1 m in plan, were subjected to static forces...
The 2005 edition of the National Building Code of Canada (NBCC) will adopt a companion-action format for load combinations and specify wind and snow loads based on their 50 year return period values. This paper pres- ents the calibration of these factors, based on statistics for dead load, live load due to use and occupancy, snow load, and wind loa...
The 2005 edition of the National Building Code of Canada (NBCC) will adopt a companion-action format for load combinations and specify wind and snow loads based on their 50 year return period values. This paper sum- marizes statistics for dead load, live load due to use and occupancy, snow load, and wind load that have been adopted for calibration,...
The mechanical properties of ASTM A992 steel were determined by tests of 207 flat-strap tensile test specimens at the University of Minnesota and the University of Western Ontario carried out in accordance with ASTM A370. Samples were obtained from 38 heats of steel from eight different shapes provided by three producers. The resultant data were an...
A method for computing the variance of the strength of a compound member consisting of identical mass-produced ductile elements is presented that accounts for correlation between the strengths of the individual elements. The individual element strengths are represented as a first-order, zero-mean, autoregressive time series and the associated varia...
A two-step method for converting a concrete core compression test result to the in-place strength of the corresponding volume of concrete is presented. The strength of a non-standard core is first converted to the equivalent strength of a standard core, and then the standard core strength is converted to the equivalent in-place strength. Strength c...
The facility performance requirements for the Confederation Bridge specified that the bridge be designed using load and resistance factors developed specifically for the site. This paper reviews the derivation of these factors for both the ultimate limit states and the serviceability limit states.
A procedure for the determination of concrete strength value from core strength data is described. The procedure involves (a) planning of the scope of the testing program, (b) procuring and testing of cores, (c) conversion of core strength to equivalent in-place strengths, (d) identification of low outliers in the set of equivalent in-place strengt...
An experimental investigation involving 287 concrete core specimens obtained from large beams cast from 45 to 90 MPa (6500 to 13,000 psi) ordinary portland cement concretes is described. The data indicate the effect of variations of core size and test moisture condition on the measured compressive strength of cores from elements made of high-perfor...
Data are analyzed to determine the effect of the specimen length-to-diameter ratio (l/d) on the magnitude and precision of the compressive strength of concrete cores. The data represent strength tests of 758 core specimens, all 4 in. in diameter, obtained from 10 different elements cast from ordinary portland cement concretes with strengths between...
In accordance with the provisions of ASTM C 42-90 and ACI 318-89, it is current practice to either dry concrete core specimens in air for 7 days or soak them in lime-saturated water for at least 40 hr before they are tested. In this paper, the effect of moisture condition on the strengths of mature cores obtained from well-cured elements is investi...
Damage due to hurricanes and other windstorms has increased dramatically in recent years, incurring losses of life and property around the world. Houses are the most common structures and are also the most affected structures during extreme events. They are complex because of their highly redundant, yet vaguely defined, structural systems. A new fu...
Citations
... Although overlaid decks experience some stresses due to mechanical loading from traffic, the main concern for repair concrete is thermal compatibility between the overlay and substrate concretes (Silfwerbrand 2003). Differences in the thermal properties of the substrate and overlay concretes can induce stresses caused by restrained shrinkage from overlay placement on mature substrate (Orta and Bartlett 2014). Thermal effects can cause stresses at the bonded interface due to different thermal properties of the overlay and substrate concretes (Silfwerbrand 2003). ...
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... To eradicate this problem, technicians need to cut concrete core without having reinforcement by scanning through magnate. Bartlett and MacGregor proposed corrections for concrete core strength if cores contain reinforcement [9]. The corrections are shown in Table 1. Bartlett and Macgregor adjustments are for the reinforcement which runs at right angles to the direction of drilling. ...
... In this test, a steel bar is embedded in a prismatic specimen along a defined length and stressed at one end by a compressive force, and the remaining end is not stressed [12]. The push-out test is relatively simple and mainly applicable for smooth rebar, as they are prone to slipping during pull-out [68,106]. In the selected bibliography, it was employed in almost 5 % of the articles. ...
... It is generally agreed that the compressive strength of the extracted core can be obtained by dividing the ultimate load by the cross-sectional area of the core, calculated from the average diameter; however, the critical issue is to translate this result into cube strength. In fact, the compressive strength of the concrete cores is affected by a number of factors such as slenderness ratio of sample (ratio between sample length and sample diameter, λ = l/d), the direction of drilling (parallel or perpendicular to casting direction), diameter value (50 mm, 100 mm, or 150 mm), presence of reinforcement steel bars in the specimen, moisture condition of the core specimen and the effect of drilling damage to the sample [34][35][36][37][38][39]. Table 1 summarizes the factors considered in American code, European code, Egyptian code, British standards and Concrete society to interpret core strength to in-situ concrete strength. ...
... Wzrost wilgotności ABK (32)(33)(34)(35)(36) ...
... Rights reserved. (Ellingwood et al., 1982), and the material properties are based on (Bartlett et al., 2003). ...
... Even so, plain bars are still widely present in historical RC structures which, in many cases, now require assessment and rehabilitation [8]. Only a few studies of beams which include corroded plain bars are available in the current state-of-the-art [9][10][11] and the behaviour they describe differs significantly, as compared to corroded RC members with ribbed bars. ...
... Fabbrocino et al. [14] conducted experiments on smooth rebars to describe the force-slip dependency for the bond phenomenon and anchor details. Feldman and Bartlett [15] analytically and experimentally indicated that bond stress changes along the length of smooth bars in pullout specimens, and they added that the position of the maximum bond stress fluctuates from the loaded end towards the unloaded end of the concrete specimen with increasing applied load. Ertzibengoa et al. [16] investigated the bond performance of flat stainless reinforcement bars (both smooth and deformed) in concrete through 72 pull-out tests in comparison with the carbon steel deformed rebars. ...
... Large attention has been DOI 10.1201/9781003316404-44 devoted to the assessment of the influence of specimen height given the same width. Based on experimental datasets and numerical validations, several functions of correction factors have been proposed to unify nominal strengths of specimens of different slenderness (MacGreggor 1994). Taking into account the specific differences of the various functions proposed in literature, these all show that a smaller slenderness gives a higher apparent nominal strength (HB 195 -The Australian earth building handbook-Standards Australia International, NSW 2001, 2001 In samples with low slenderness, an artificial strengthening is caused by the restraining effects of the steel material platens of the testing apparatus. ...
... In this framework, this paper proposes a novel emergency housing system realised by alveolar corrugated cardboard panels, namely the Archicart (Cardboard Architecture) system [17]. ...
