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The blast resistance of a typical two-lane steel girder highway bridge structural system was modeled using a nonlinear finite-element approach that considered material damage, fracture, and separation. Critical blast scenarios were based on field observations of terrorist attacks on bridges in Iraq, while system failure was defined in terms of practical emergency serviceability criteria used on actual blast-damaged bridges. The blast resistance of various design parameters was assessed, including the number of girders, deck concrete strength, reinforcement ratio, slab thickness, girder and reinforcement yield strength, girder sectional dimensions, and pier column width. The presented approach uniquely quantifies structural system blast resistance in terms of the charge weight that can be applied at different locations until failure. A sensitivity analysis was conducted to determine the most influential design parameters. It was found that system blast capacity was primarily influenced by the number of girders and girder yield strength, while additional significant parameters were deck compressive strength, deck thickness, web stiffener width, and girder depth. Secondary parameters were deck reinforcement ratio, girder flange, and web thickness, while deck reinforcement yield stress was found to be insignificant. Based on the results, recommendations for improving blast resistance are provided. [ABSTRACT FROM AUTHOR]

This paper summarizes the blast events and resulting damage found on more than 100 bridges in Iraq caused by terrorist attacks. Most structures were two to three lanes wide and composed of a superstructure with prestressed concrete beams that supported a concrete deck. In most cases, terrorists placed charges either on the deck or at the base of columns. Typical structural system failures were due to either intermediate column failure, girder end failure, or girder end failure in combination with midspan failure. It was found that a single blast load on the deck rarely caused collapse, while three or more blast loads distributed across the deck nearly always caused deck and/or span collapse. If at least two girders remained largely undamaged, one lane of traffic could often be directed safely over the structure, allowing a heavily damaged bridge to remain in temporary use. When columns were attacked, charges placed symmetrically caused the columns to collapse downward, whereas charges placed asymmetrically caused significant lateral movement. Although most bridges were simple span, substantial resiliency was observed, where the structures could support large amounts of load even when some critical components theoretically had near-zero capacity. It was further found that separating components, even slightly, could significantly reduce blast damage propagation. Brief recommendations are given to mitigate blast damage. [ABSTRACT FROM AUTHOR]

The reliability of reinforced concrete bridge beams that are flexurally strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) laminates according to current AASHTO design provisions was quantified. The flexural resistance model considers resistance loss due to the effect of bar corrosion, FRP rupture, and debonding. Random variables were used to characterize uncertainties in as-constructed initial beam geometry and material properties, as well as loads and loss of beam resistance due to steel, concrete, and CFRP system degradation. Bond strength loss was based on 19 years of actual in situ data. The effects of various critical parameters on reliability were quantified, including beam span, concrete strength, the modular ratio and unit area of CFRP, the extent of CFRP repair, and the dead/live-load ratio. It was found that a large inconsistency in reliability exists among CFRP-repaired beams designed according to AASHTO provisions, the primary cause of which is variability in debonding potential. The results demonstrate the importance of including a well-developed bond strength model in the design process. Recommendations are provided. [ABSTRACT FROM AUTHOR]

This study discusses the development of a procedure that can be used to assess the reliability of concrete masonry unit infill walls subjected to personnel-delivered blast loads. Consideration is given to maintain reasonable computational effort for both the structural analysis and reliability models. Blast load and wall resistance models are developed based on experimental and analytical data, and resistance is evaluated with a large strain, large displacement transient dynamic finite-element analysis. A sensitivity analysis is conducted to identify significant random variables and a reliability analysis conducted with a feasible level of computational effort. Reliability indices are estimated for two wall types and three design blast load levels in terms of wall failure as well as occupant injury, over various load frequency-of-occurrence times. DOI: 10.1061/(ASCE)0733-9445(2007) 133:7(935) CE Database subject headings: Blast loads; Concrete masonry; Walls; Explosions; Concrete structures; Concrete blocks.

The loads associated with Hurricane Katrina led to the destruction or severe damage of approximately 130,000 homes and over 200 deaths in the state of Mississippi. This paper discusses the results of a field inspection of structural damage along the state's Gulf Coast area caused by this hurricane. It was found that reinforced concrete, steel frame, and heavy timber structures generally performed well, with minimal structural damage. Precast concrete, light frame wood, and bridge structures generally performed poorly. Nonstructural components of all building types, in particular facades and interior partitions subjected to storm surge, were typically destroyed. For various structures, the primary cause of failure was found to be insufficient connection strength. A comparison of Katrina's storm surge and wind loads is made to those specified in current design standards. It was found that Katrina's forces exceeded those specified in design standards in many parts of the state. DOI: 10.1061/(ASCE)0887-3828(2007)21:2(117) CE Database subject headings: Hurricanes; Damage; Gulf of Mexico; Storm surges.

A reliability-based optimization procedure is developed and applied to minimize the weight of eight fiber-reinforced polymer composite bridge deck panel configurations. The method utilizes interlinked finite element, optimization, and reliability analysis procedures to solve the weight minimization problem with a deterministic strength constraint and two probabilistic deflection constraints. Panels are composed of an upper face plate, lower face plate, and a grid of interior stiffeners. Different panel depths and stiffener layouts are considered. Sensitivity analyses are conducted to identify significant design and random variables. Optimization design variables are panel component ply thicknesses, while random variables include load and material resistance parameters. It was found that panels were deflection governed, with the optimization algorithm yielding little improvement for shallow panels, but significant weight savings for deeper panels. The best design resulted in deep panels with close stiffener spacing to minimize local upper face plate deformations under the imposed traffic (wheel) loads. CE Database subject headings: Structural reliability; Optimization; Composite materials; Bridges; Bridge decks.

Concrete masonry unit walls subjected to blast pressure were analyzed with the finite element method, with the goal of developing a computatitonally efficient and accurate model. Wall behavior can be grouped into three modes of failure, which correspond to three ranges of blast pressures. Computational results were compared to high-speed video images and debris velocities obtained from experimental data. A parametric analysis was conducted to determine the sensitivity of computed results to critical modeling values. It was found that the model has the ability to replicate experimental results with good agreement. However, it was also found that, without knowledge of actual material properties of the specific wall to be modeled, computational results are not reliable predictors of wall behavior. CE Database subject headings: Finite element method: Walls: Blast loads: Explosions: Concrete masonry; Concrete structures: Concrete blocks: Nonlinear analysis.

Time-dependent flexural deformations for composite and noncomposite prestressed concrete beams and steel–concrete composite beams, which are subject to various loading and unloading events, are predicted based on several methods with varying levels of complexity. The considered prediction methods range from computational methods that provide curvatures at various points along the span as a function of time to widely used multiplier-based methods. The impact of various levels of analytical simplification on beam flexural deformation history is quantified. Pre-erection camber predictions based on various methods are compared with measured pre-erection camber values for 105 noncomposite prestressed concrete beams. Similarly, predictions for the full flexural deformation history of six composite prestressed concrete and six steel beams are compared with test data reported in the literature. All computational methods considered result in similar predictions of pre-erection camber in prestressed concrete beams despite fundamental differences in the methods and despite gross simplifications in creep behavior used in some methods. However, when long-term flexural deformations at service and prediction of beam rebound are considered, the effect of simplifying assumptions for creep behavior becomes more significant. The quantification of such differences in predictions may inform decisions during the design phase regarding which method should be employed for a particular application. [ABSTRACT FROM AUTHOR]

A methodology will be presented to predict the complete history of flexural deformations in composite prestressed concrete and steel beams from inception to the end of service life, which will include a prediction of beam rebound and subsequent deformations when the deck is replaced. The methodology will use distinct creep curves for each loading event and will provide an efficient framework to account for the effects of differential creep, differential shrinkage, shrinkage-induced creep, loading time, concrete aging, prestress losses, and temperature gradients on composite and noncomposite beam flexural deformation history. The method will be based on a time-dependent strain compatibility analysis, which will provide curvatures at various points along the span as a function of time to obtain the history of the deflected shape of the beam. Measured discrete and periodic flexural deformation data will be used to validate the methodology. The presented method will be used to quantify the influence of creep, shrinkage, modulus of elasticity models, temperature gradients, deck placement and replacement time, and time step generation method on the beam flexural deformation history. The results show that steel beams can rebound to their original position after the deck has been removed, the rebound in the prestressed concrete beams varied from 51% to 92%. In addition, the influence of the initial deck placement time had a marked effect on the short-term beam flexural deformations at service, and its influence diminished after 200 days for the cases that were considered in this study. In addition, the selection of models for creep, shrinkage, and modulus of elasticity at prestress release and 28 days had a marked effect on the beam deformation history, and the considered models for the variation in modulus with time resulted in similar predictions. [ABSTRACT FROM AUTHOR]

Soil--steel composite bridges (SSCB) have become increasingly popular for short-span bridges as an alternative to concrete slab bridges mainly due to their low initial cost, rapid manufacture, simplified construction, and geometrical adaptability. SSCBs have a variety of applications and can be used over waterways or roadways. While conventional bridges tend to lose their load-carrying capacity due to degradation, SSCBs gain strength because of backfill soil consolidation. However, the load carrying capacity and integrity of such structures highly depends on the condition and load-carrying capacity of the steel arch element. A major drawback of SSCBs, especially those located on waterways or with poor drainage, is corrosion and subsequent loss of cross-sectional capacity. Unfortunately, the inspection of such bridges is not straightforward and any damage/collapse will be very costly to repair/replace. Fiber reinforced polymer (FRP) composites offer an attractive alternative to replace the steel in these types of bridges. FRP composites have significantly improved durability characteristics compared to steel, which will reduce maintenance costs and improve lifecycle costs (LLCs). This paper presents a new concept to use glass FRP as a construction material to construct soil--FRP composite bridges (SFCB). Various aspects of design and manufacturing are presented along with results and conclusions from a case study involving alternative bridge designs in steel and FRP composites. [ABSTRACT FROM AUTHOR]

A new approach to incorporate scrap tire material into concrete was investigated, in which two reclaimed waste tire components, carbon black and fuel oil, were used to replace a portion of water. The effect of liquid tire content to water ratios from 5% to 40% on an otherwise typical concrete mix were assessed, and compressive and flexural strength, flexural toughness, modulus of elasticity, and several fresh concrete properties were determined. Results were compared with typically expected results of traditional shredded tire mixes with equivalent tire content. It was found that the liquid tire mixes had significantly smaller losses of compressive strength and workability than did shredded rubber mixes; increased flexural strength compared with traditional concrete mix; and significantly decreased stiffness compared with traditional and shredded tire mixes. [ABSTRACT FROM AUTHOR]

Various local governments have developed state-specific vehicular live-load factors for bridge rating. However, a significant computational demand is often associated with such an effort. This is due to the large size of the weigh-in-motion (WIM) databases frequently used in the procedure. In this study, a method is proposed that can significantly reduce the computational cost of the analysis, while still maintaining reasonable accuracy. The proposed approach develops approximate live-load random-variable statistics by truncating the WIM database based on gross vehicle weight, and then a complete reliability analysis is conducted to develop new live-load factors that meet AASHTO-specified rating standards. Two WIM databases, one based on typically legal vehicles and another based on unusually heavy vehicles, are considered for evaluation. Results of the proposed approach are compared with an exact assessment as well as to a simplified method suggested by AASHTO. It was found that the proposed approach may provide very large reductions in computational cost with minimal loss of accuracy, whereas significant inaccuracies were found with the existing simplified approach. [ABSTRACT FROM AUTHOR]

Byline: Masoud Rais-Rohani, Kiran N. Solanki, Erdem Acar, Christopher D. Eamon This paper presents the results of a study on the combined shape and sizing optimisation of automotive structures while examining the effects of different design constraints and associated uncertainties on reliability and efficiency of the optimum designs. Nonlinear transient dynamic finite element analysis is used for full- and offset-frontal crash simulations of a full vehicle model. Surrogate models are developed for the intrusion distance and peak acceleration responses at different vehicle locations based on the material and geometric characteristics of the rail component. The obtained solutions provide insight on the effect of uncertainties in optimum design of automotive structures.

This study involved laboratory testing of two full-scale AASHTO Type II prestressed concrete (PC) girders. Each girder was tested in three different regions of the span by adjusting support and loading locations to generate data for different critical shear span-depth (a/d) ratios and stirrup spacings. Test regions had stirrup spacings from 0.28 to 0.72 d and a/d from 2.0 to 3.4. The purpose of the testing was to validate a simplified numerical (finite element analysis [FEA]) model that can be used to reasonably predict the shear behavior of PC girders. Experimentally obtained shear strengths were compared to AASHTO LRFD, Interim 1979, and ACI code-calculated strengths. The developed FEA model appears to be a relatively simple and reliable tool that can be used to predict the shear behavior of PC girders, while the design codes evaluated led to very conservative estimations of shear strength. [ABSTRACT FROM AUTHOR]

In this study, an adjustment factor was developed to better estimate the shear capacity of simple span prestressed concrete (PC) girders, for intended use in load rating. The adjustment factor is expressed as a function of several critical girder parameters including concrete strength, prestress level, stirrup spacing, and girder height. The adjustment factor was determined from a regression analysis of over 200 shear capacity results. The database was obtained from a parametric analysis conducted with a finite-element model validated with experimental data. Three different code methods were considered for comparison. Generally, code results were found to be inconsistently conservative. Application of the adjustment factor to an established procedure produced improvement in the accuracy and consistency of shear capacity estimation over existing code methods for the range of girder parameters considered. In addition, potential effects on rating factors for inventory and operational levels were quantified. [ABSTRACT FROM AUTHOR]

Various characteristics of a structure influence its response when subjected to a blast load. This has important implications for survivability and resistance to progressive collapse. In this study, the effect of the type of lateral load resisting system on reinforced concrete (RC) building resistance to progressive collapse when exposed to blast load was examined. Fourteen different reinforced concrete structures were considered for analysis, with five structures designed as moment-resisting frames and nine designed as shear wall systems. Buildings with 3, 6, and 10 stories with 3-, 4-, and 5-bay symmetric configurations were considered. The structures were exposed to external and internal charges, whereas the nonlinear, transient dynamic analysis of collapse behavior was investigated with a finite-element-based approach, the applied element method (AEM). The results show that the shear-wall structures and structures larger in height and plan generally provide greatest resistance to blast damage and progressive collapse. [ABSTRACT FROM AUTHOR]

In this study, a reliability-based calibration of live-load factors for bridge design specific to the state of Michigan was conducted. Two years of high-frequency weigh-in-motion (WIM) data from 20 representative statewide sites were analyzed, and load effects were generated for bridge spans from 6 to 122 m (20 to 400 ft), considering simple and continuous moments and shears, and single-lane and two-lane effects. Seventy-five-year statistics for maximum live load were then estimated with probabilistic projection. Bridge girders considered for the calibration included composite steel, prestressed concrete, side-by-side and spread box beams, and special long-span structural members. In some cases, it was found that Michigan load effects were greater than those previously assumed, often requiring higher load factors than those in current use. Moreover, significant variation in the required load factor was found, potentially resulting in significant inconsistencies in reliability if a single load factor is used for the design of all bridge types and load effects considered. [ABSTRACT FROM AUTHOR]

Two similar bridges constructed with a live-load continuous connection were tested for live-load distribution and joint continuity. Girder distribution factors (GDFs) were compared with AASHTO equivalent values. For positive moments on all girders as for negative moments on interior girders, results using AASHTO equivalent GDFs were found to be generally conservative. However, for negative moments on exterior girders, test results exceeded AASHTO values, significantly so with two-lane results. GDF results were verified with a finite-element analysis (FEA) model, which produced behavior similar to the field tests. With respect to joint continuity, it is estimated that a simple span would produce a maximum positive moment about 7% higher than the actual structure, whereas a completely continuous structure would produce a maximum positive moment about 16% lower than that of the actual structure. For negative moments, the actual structure experienced about 28% of that of a continuous structure. Shear reactions were also investigated. Recommendations are proposed for evaluating transverse distribution of live load as well as the longitudinal distribution of live load, accounting for the effect of joint continuity. [ABSTRACT FROM AUTHOR]

An analytical procedure is used to study the effects of moment gradient and load height on the elastic stability of wide flange steel beams. Lateral torsional buckling is the limit state considered. Solutions are developed for a series of general moment functions which are produced by continuous load types with possible end moments. For each load type, an equivalent uniform moment factor is developed. Additionally, a load height factor is developed to modify the equivalent uniform moment factor for these load types where loading is applied above the shear center. Solutions are processed numerically using a Taylor series polynomial approximation. Results are presented in terms of an equivalent uniform moment factor and a load height factor. Comparison with national code procedures for moment factor show discrepancies that are conservative in some circumstances by up to 51% and unconservative in others by up to 8%. The largest discrepancies occur under the effect of reverse curvature bending and load position above the shear center. Results for load position show that members loaded above their shear center are more susceptible to lateral torsional buckling than those loaded at their shear center. Some design examples are presented using the load height factors developed. [ABSTRACT FROM AUTHOR]

Steel-reinforced concrete structural components are often associated with significant maintenance costs as a result of reinforcement corrosion. To mitigate this problem, fiber-reinforced polymer bars have been used in place of traditional steel-reinforcement for some applications. The non-ductile response of typical fiber-reinforced polymer bars is a concern, however. To overcome this problem, hybrid ductile fiber-reinforced polymer bars have been developed for use in concrete flexural members with resulting ductility indices similar to sections reinforced with steel. In this study, five different hybrid ductile fiber-reinforced polymer bar concepts are analyzed and compared in terms of ductility, stiffness, and relative cost. Of primary interest is the effect that the number of materials used in bar construction has on performance. Reinforced concrete beam and bridge deck applications are considered for analysis. It was found that all hybrid ductile fiber-reinforced polymer-reinforced flexural members czonsidered could meet code-specified strength and ductility requirements for steel-reinforced sections, although service load deflections were approximately twice that of steel-reinforced sections of the same depth. In general, ductility increased, and overall material cost decreased, as the bar material layers increased from 2 to 4. The four-material continuous fiber bar approach was found to be most promising, with high ductility as well as relatively low cost. [ABSTRACT FROM PUBLISHER]

Abstract: A reliability analysis is conducted on reinforced concrete columns subjected to fire load. From an evaluation of load frequency of occurrence, load random variables are taken to be dead load, sustained live load, and fire temperature. Resistance is developed for axial capacity, with random variables taken as steel yield strength, concrete compressive strength, placement of reinforcement, and section width and height. A rational interaction model based on the Rankine approach is used to estimate column capacity as a function of fire exposure time. Various factors were considered in the analysis such as fire type, load ratio, reinforcement ratio, cover, concrete strength, load eccentricity, and other parameters. Reliability was computed from 0 to 4h of fire exposure using Monte Carlo simulation. It was found that reliability decreased nonlinearly as a function of time, while the most significant parameters were fire type, load ratio, eccentricity, and reinforcement ratio. [Copyright &y& Elsevier]

Highlights: [•] A RBDO procedure is developed and applied to DHFRP-reinforced flexural members. [•] Strength, ductility, stiffness, and reliability constraits are considered. [•] Bars are optimized for cost minimization for a bridge deck and building beam. [•] Small differences in optimial configuration were found for the different applications. [Copyright &y& Elsevier]

To prevent damage caused by corroding reinforcement, fiber-reinforced polymer (FRP) reinforcing bars have been used in place of steel in a relatively small but increasing number of structures in civil infrastructure. A concern with the use of traditional FRP bars, however, is the resulting lack of ductility. This problem has been overcome with the development of a new generation of composite reinforcement, ductile hybrid FRP (DHFRP) bars. However, standards that address the design of DHFRP bars are unavailable, and appropriate resistance factors for the use of DHFRP reinforcement are unknown. In this paper, a reliability analysis is conducted on tension-controlled concrete flexural members reinforced with DHFRP with the intent to estimate potential strength-reduction factors. Flexural members considered include a selection of representative bridge decks and building beams designed to meet strength requirements and target reliability levels dictated by relevant engineering standards. Nominal moment capacity is calculated from standard analytical models and is taken as first DHFRP material failure. Statistical parameters for load and resistance random variables in the reliability model are consistent with previous code calibration efforts. The resulting resistance factors ranged from 0.61-0.64 for tension-controlled sections, which indicates a potential increase in allowed strength with respect to flexural members using nonductile bars. [ABSTRACT FROM AUTHOR]

A procedure for conducting reliability analysis of RC beams subjected to a fire load is presented. This involves identifying relevant load combinations, specifying critical load and resistance random variables, and establishing a high-temperature performance model for beam capacity. Based on the procedure, an initial reliability analysis is conducted using currently available data. Significant load random variables are taken to be dead load, sustained live load, and fire temperature. Resistance is in terms of moment capacity, with random variables taken as steel yield strength, concrete compressive strength, placement of reinforcement, beam width, and thermal diffusivity. A semiempirical model is used to estimate beam moment capacity as a function of fire exposure time, which is calibrated to experimental data available in the literature. The effect of various beam parameters was considered, including cover, beam width, aggregate type, compressive strength, dead to live load ratio, reinforcement ratio, support conditions, mean fire temperature, and other parameters. Using the suggested procedure, reliability was estimated from zero to 4 h of fire exposure using Monte Carlo simulation. It was found that reliability decreased nonlinearly as a function of time, whereas the most significant parameters were concrete cover; span/depth ratio when axial restraints are present, mean fire temperature, and support conditions. [ABSTRACT FROM AUTHOR]

PUBLIC 46: Prime Mover is a selection of five essays corresponding to five hypothetical exhibitions of works from an influential private collection with which Eamon was professionally involved for more than ten years. The collection, one of the first in private hands to focus almost exclusively on time-based media, has been the subject of a number of graduate theses and museum catalogues, but this publication aims to bolster these efforts towards better understanding of a collection that has altered the field of media art. In a sense, these essays constitute a history of moving-image art starting from around 1900 that is meant to be a resource for students of film and video art, on the one hand, and for scholars investigating the history of collections on the other. Although the five exhibitions imagined here evolved separately, they can be read as chapters of a continuous story, or, alternatively, they can be read as different lenses through which one can look at the history of media art itself, as a necessarily fragmentary history. The different formats and different approaches in this publication all come from the curator's toolbox, where one is able to place works of art in a variety of contexts, grouping them in ways that both illuminate the works and, hopefully, the history of art as well. [ABSTRACT FROM AUTHOR]

PUBLIC 46: Prime Mover is a selection of five essays corresponding to five hypothetical exhibitions of works from an influential private collection with which Eamon was professionally involved for more than ten years. The collection, one of the first in private hands to focus almost exclusively on time-based media, has been the subject of a number of graduate theses and museum catalogues, but this publication aims to bolster these efforts towards better understanding of a collection that has altered the field of media art. In a sense, these essays constitute a history of moving-image art starting from around 1900 that is meant to be a resource for students of film and video art, on the one hand, and for scholars investigating the history of collections on the other. Although the five exhibitions imagined here evolved separately, they can be read as chapters of a continuous story, or, alternatively, they can be read as different lenses through which one can look at the history of media art itself, as a necessarily fragmentary history. The different formats and different approaches in this publication all come from the curator's toolbox, where one is able to place works of art in a variety of contexts, grouping them in ways that both illuminate the works and, hopefully, the history of art as well. [ABSTRACT FROM AUTHOR]

PUBLIC 46: Prime Mover is a selection of five essays corresponding to five hypothetical exhibitions of works from an influential private collection with which Eamon was professionally involved for more than ten years. The collection, one of the first in private hands to focus almost exclusively on time-based media, has been the subject of a number of graduate theses and museum catalogues, but this publication aims to bolster these efforts towards better understanding of a collection that has altered the field of media art. In a sense, these essays constitute a history of moving-image art starting from around 1900 that is meant to be a resource for students of film and video art, on the one hand, and for scholars investigating the history of collections on the other. Although the five exhibitions imagined here evolved separately, they can be read as chapters of a continuous story, or, alternatively, they can be read as different lenses through which one can look at the history of media art itself, as a necessarily fragmentary history. The different formats and different approaches in this publication all come from the curator's toolbox, where one is able to place works of art in a variety of contexts, grouping them in ways that both illuminate the works and, hopefully, the history of art as well. [ABSTRACT FROM AUTHOR]

PUBLIC 46: Prime Mover is a selection of five essays corresponding to five hypothetical exhibitions of works from an influential private collection with which Eamon was professionally involved for more than ten years. The collection, one of the first in private hands to focus almost exclusively on time-based media, has been the subject of a number of graduate theses and museum catalogues, but this publication aims to bolster these efforts towards better understanding of a collection that has altered the field of media art. In a sense, these essays constitute a history of moving-image art starting from around 1900 that is meant to be a resource for students of film and video art, on the one hand, and for scholars investigating the history of collections on the other. Although the five exhibitions imagined here evolved separately, they can be read as chapters of a continuous story, or, alternatively, they can be read as different lenses through which one can look at the history of media art itself, as a necessarily fragmentary history. The different formats and different approaches in this publication all come from the curator's toolbox, where one is able to place works of art in a variety of contexts, grouping them in ways that both illuminate the works and, hopefully, the history of art as well. [ABSTRACT FROM AUTHOR]

People that the author would like to thank for their assistance to the journal "PUBLIC" are mentioned.

The article introduces a collection of essays corresponding to five exhibitions of works from an influential private collection.

PUBLIC 46: Prime Mover is a selection of five essays corresponding to five hypothetical exhibitions of works from an influential private collection with which Eamon was professionally involved for more than ten years. The collection, one of the first in private hands to focus almost exclusively on time-based media, has been the subject of a number of graduate theses and museum catalogues, but this publication aims to bolster these efforts towards better understanding of a collection that has altered the field of media art. In a sense, these essays constitute a history of moving-image art starting from around 1900 that is meant to be a resource for students of film and video art, on the one hand, and for scholars investigating the history of collections on the other. Although the five exhibitions imagined here evolved separately, they can be read as chapters of a continuous story, or, alternatively, they can be read as different lenses through which one can look at the history of media art itself, as a necessarily fragmentary history. The different formats and different approaches in this publication all come from the curator's toolbox, where one is able to place works of art in a variety of contexts, grouping them in ways that both illuminate the works and, hopefully, the history of art as well. [ABSTRACT FROM AUTHOR]

This paper presents a life-cycle cost analysis (LCCA) of prestressed concrete highway bridges using carbon fiber-reinforced polymer (CFRP) reinforcement bars and strands. Side-by-side box beam and AASHTO beam bridge structures were considered over several span lengths and traffic volumes. The results show that despite the higher initial construction cost of CFRP reinforced bridges, they can be cost-effective when compared to traditional steel-reinforced bridges. The most cost-efficient design was found to be a medium-span CFRP reinforced AASHTO beam bridge located in a high-traffic area. A probabilistic analysis revealed that there is greater than a 95% probability that the CFRP reinforced bridge will become the least expensive option between 20 and 40 years of service, depending on traffic volume and bridge geometry. The break-even year between CFRP and steel reinforcement is typically at the time of the first major repair activity on the steel-reinforced concrete bridge. [ABSTRACT FROM AUTHOR]

A life-cycle cost analysis (LCCA) was conducted on prestressed concrete bridge superstructures using carbon fiber reinforced polymer (CFRP) bars and strands. Traditional reinforcement materials of uncoated steel with cathodic protection and epoxy-coated steel were also considered for comparison. A series of deterministic LCCAs were first conducted to identify a range of expected cost outcomes for different bridge spans and traffic volumes. Then, a probabilistic LCCA was conducted on selected structures that included activity timing and cost random variables. It was found that although more expensive initially, the use of CFRP reinforcement has the potential to achieve significant reductions in life-cycle cost, having a 95% probability to be the least expensive alternative beginning at year 23-77 after initial construction, depending on the bridge case considered. In terms of life-cycle cost, the most effective use of CFRP reinforcement was found to be for an AASHTO beam bridge in a high traffic volume area. [ABSTRACT FROM AUTHOR]

Abstract: A simulation-based structural reliability analysis method is presented. It is intended as an alternate approach to estimate reliability for problems for which most-probable point of failure methods fail and when computational resources are limited. The proposed method combines conditional expectation and estimating the PDF or CDF of a selected portion of the limit state. In the proposed approach, complex limit state functions are simplified to two random variable problems. The success of the simplification depends on the quality of the CDF estimate. Results indicate that the method may provide accurate and efficient solutions for some difficult reliability problems. [Copyright &y& Elsevier]

A structural reliability model is developed for a large composite submarine sail structure. Random variables include material strength and stiffness properties as well as load. Limit states are formulated in terms of material strength parameters and buckling resistance. A series system reliability model that bases structural performance on first component failure is used. A total of 205 random variables and 117 limit states compose the structural system model. Most component reliability indices ranged from 3 to 7, with overall system failure governed by material in-plane shear with a reliability index of 1.84. A probabilistic sensitivity analysis determined that load and material strength were the most significant random variables, while material stiffness parameters were unimportant. Significant computational effort was saved by reducing the number of random variables to the most influential set. The effects of correlation and random variable probability distribution were explored. It was found that correlation has little effect on results, but probability distribution is significant. Recommendations are made to improve performance. [ABSTRACT FROM AUTHOR]

The objective of this study is to summarize the load and resistance criteria for highway bridge plank decks, and to estimate the reliability of plank decks designed by the AASHTO Code. Both transverse and longitudinal planks for a variety of typical stringer spacings and plank sizes are considered. Truck traffic load data are based on the model used to calibrate the 1994 AASHTO LRFD Code. However, for plank decks, wheel load rather than whole vehicle weight is most important, and these statistics are developed for this study. For wood planks, dead load and dynamic load are not significant. The limit state considered is flexural strength, and resistance statistics are presented for wood planks in terms of modulus of rupture. Special flat-wise use data are presented to account for section aspect ratio as well as edge of load application. The reliability analysis is carried out using the procedure developed for calibration of AASHTO LRFD. Reliability indices for both the AASHTO Standard and AASHTO LRFD Code are presented for plank decks. The results indicate that there are considerable differences in plank reliability indices. Causes of inconsistencies in safety are identified. [ABSTRACT FROM AUTHOR]

The paper presents the calibration procedure and background data for the development of design code provisions for wood bridges. The structural types considered include sawn lumber stringers, glued-laminated girders, and various wood deck types. Load and resistance parameters are treated as random variables, and therefore, the structural performance is measured in terms of the reliability index. The statistical parameters of dead load and live (traffic) load, are based on the results of previous studies. Material resistance is taken from the available test data, which includes consideration of the post-elastic response. The resistance of components and structural systems is based on the available experimental data and finite element analysis results. Statistical parameters of resistance are computed for deck and girder subsystems as well as individual components. The reliability analysis was performed for wood bridges designed according to the AASHTO Standard Specifications and a significant variation in reliability indices was observed. The recommended load and resistance factors are provided that result in consistent levels of reliability at the target levels. [ABSTRACT FROM AUTHOR]

Numerical design optimization coupled with finite-element analysis is applied to an advanced design concept for a submarine sail structure made of composite materials. Through a detailed design sensitivity analysis, the influence of stiffener and skin sizing on the weight and buckling characteristics of the sail structure is quantified. Furthermore, the sail is optimized for minimum weight under a severe loading condition based on two alternative discretization concepts for modeling the variations in skin thickness. The design constraints include the lower-bound limits on load factors corresponding to the lowest 10 buckling modes as well as the allowable normal and shear strains in each ply. The sizing optimization problem is solved using the modified exterior penalty function method. The results indicate that depending on the discretization concept, it is possible to reduce the structural weight by as much as 14% over the baseline model while meeting all the structural design criteria. As part of the postoptimization evaluation of the optimal design models, such response characteristics as the linear and nonlinear buckling were evaluated under a diverse set of loading conditions with the results showing a similar or superior performance as compared to the baseline model. [ABSTRACT FROM AUTHOR]