Deck System Research Articles

Reliability-Based Performance Model for Large Bridge Component Systems

A method for modeling the performance of large bridge components subjected to normal loading and deterioration effects using reliability engineering techniques is presented. Development of the method was motivated by the need to advance a practical performance model for large bridge rehabilitation decision analysis. The modeling scope includes three basic elements: performance assessment, system modeling, and failure rate analysis. Two fundamental assumptions of the developed performance model are that (a) bridge components are systems of independent critical elements and (b) each element’s failure rate is constant throughout its functional service life. The model is used to qualitatively assess the performance of bridge components with respect to reliability and enables the estimation of two important rehabilitation planning indices, functional service life and expected damage. An application of the model is illustrated in an example involving a comparative evaluation of the performance of two large bridge deck systems. The bridges selected have similar traffic, maintenance, and environmental conditions; however, they have significantly different design characteristics. It is concluded that the performance model provides a viable approach to qualitative and quantitative evaluation of bridge performance over time. The research efforts described are part of a larger, comprehensive project to develop and enhance the bridge management system of the New York State Thruway Authority.

Replacement of reinforced concrete deck of Champlain Bridge, Montreal, by orthotropic steel deck

The Champlain Bridge, Montreal, Quebec, has recently undergone replacement of its deteriorated reinforced concrete deck situated over the St. Lawrence Seaway with a new orthotropic steel deck. The new deck consists of 210 prefabricated steel panels which have been installed at the rate of one panel per night. The panels arrived on site with a base course of pavement to allow traffic flow over the new panels without disrupting the rush hour and daytime traffic. As a result of the new deck being 25% lighter in weight, the reserve strength capacity of the steel superstructure to accommodate live loads has increased sufficiently to bring the bridge within the governing live load requirements of the CAN/CSA Standard S6-1988 "Design of highway bridges." The governing design live loads on bridges have increased by about 50% since the original construction of the bridge over 30 years ago and reflect the larger vehicle weights permitted over Canadian roadways. Key words: alternative deck systems, cantilevered steel superstructure, closed rib stiffeners, counterweights, diaphragms, field erection, orthotropic plate deck, prefabrication, reinforced concrete, welding.

Advanced Taxi Map Display Design for Low-Visibility Operations

Conducting gate to gate operations during reduced visibility conditions is a major impediment to scheduled and unscheduled flight operations in the National Airspace System (NAS). Takeoff and landing minima are predicated on aircraft equipage and airport visibility (e.g., at some major airports, operations are terminated when visibility is below 700 ft runway visual range (RVR). Although some aircraft can land with zero-zero visibility, there are no ground or flight deck systems that allow them to taxi under low visibility conditions. A map display system designed to support low visibility taxi was evaluated by 12 B-747 flight crews in NASA's Crew Vehicle System Research Facility (CVSRF). Three taxi-map conditions were compared: paper map only, basic moving map, and advanced moving map. Crews landed and taxied along 24 different taxi routes under three visibility conditions: unlimited visibility, 700 ft RVR, and 300 ft RVR. Taxi time, errors and workload were collected for each taxi operation. Video tape recordings captured crew interactions and head-up and head-down times. Taxi times and errors were significantly better for crews with electronic maps than for crews with a paper map. Although crews with the advanced map experienced significantly more head-down time, the head down interval was significantly less than with the paper map and crew workload was significantly less. During the post-flight design review, pilots identified improvements in procedures and formatting that might enhance performance. They developed a procedure for safely switching from the NAV display to the map; and in general their comments were very favorable.

Snorre Project Execution

The Snorre field is the first truly deepwater North Sea development. It contains the largest tension-leg platform (TLP) installed to date and a large remote subsea production system. The platform went on production in Aug. 1992. Execution of large projects that use a lot of new technology provides special challenges. This article describes the project execution with a special focus on the extensive marine operations involving about 100 different activities.

Orthotropic Redecking of Bridges on the North American Continent

This article reviews major American and Canadian projects where deteriorated concrete bridge decks were replaced by steel orthotropic decks. Both open-rib and closed-rib deck systems, with long-rib spans corresponding to the spacing of existing floorbeams, were used. In three cases, the new decks are fully integrated with the main longitudinal members of the bridge. Wearing surfaces, redecking costs and the future AASHTO Bridge Design specifications provisions for orthotropic decks are discussed. The bridges which were redecked are the Golden Gate bridge, San Francisco; the George Washington bridge, New York; the Lions Gate, Vancouver BC; Throgs Neck Viaducts, New York; Benjamin Franklin bridge, Philadelphia, and the Champlain bridge over the St Lawrence river in Montreal.

FATIGUE PERFORMANCE OF SINGLE SPLICED BOLTED JOINTS IN PREFABRICATED STEEL BRIDGE DECKS

The fatigue strengths of bolted lap joints under axial load and single-spliced bolted joints in bridge deck system under bending were examined on an experimental base. In order to evaluate the local stress on the faying surface of the bolted joint, the structural restraint factor was introduced based on the measured stresses.

Categorization of Damage to Concrete Bridge Decks in Saudi Arabia

A large number of highway bridges have been built in Saudi Arabia during the past two decades. Several of these bridges have shown signs of early deterioration including serious cracking and localized failures. A number of possible causes have been hypothesized as contributing to this problem: poor construction practices, low-quality aggregates, absence of control of vehicular axle loadings, and severe environmental factors. This paper presents an overview of the types of damage identified to be most prevalent in short-span bridges in Saudi Arabia. Based on detailed in situ and laboratory investigations of some 20 girder-slab and slab-type decks, damage to the deck system may be broadly classified into (1) Structural damage, resulting from overloading of the bridges, and (2) material damage, resulting from lack of quality control and poor construction materials in an environment conducive to corrosion. An additioal causal factor contributing to damage in the arid environment is cracking due to stresses due to thermal gradients, especially in thick slab-type decks supported on minimally functional bearings which do not allow free movement at the ends.

Tie‐Rod Force Measurements in Cargo Berth

The third general cargo berth at Paradeep Port situated on the east coast of India consists of a diaphragm wall anchored to a deaoman diaphragm wall by tie‐rods. In addition, the diaphragm wall is connected to two rows of large‐diameter vertical piles by a rigid deck system. The deck system being rigid and tie‐rods flexible, the lateral loads are shared between the piles and the deadman diaphragm wall. To assess the load sharing, forces in the tie‐rods were measured before and after dredging. The results obtained were compared with those of a finite element analysis of the structural system using beam elements for the diaphragm walls, piles, and beams, and boundary elements for the soil medium. The measured tie‐rod forces compared very well with the analytical result and confirmed that a substantial portion of the lateral load was transferred to the piles. Based on the studies, the design of another berth in the vicinity was modified to retain the vertical piles and eliminate the deadman diaphragm wall and tie‐rods, resulting in substantial savings in cost and time.

Development of Economical Low‐Volume Road Bridges

Low‐volume road bridges are currently designed according to the same specifications as urban highway bridges. Thus, many of the low‐volume bridge designs are overly conservative and uneconomical. This paper addresses this issue and proposes modifications of the existing specifications in the area of fatigue, deflection, allowable stress, composite action of timber decks, bridge width, lane loading, and the use of guardrails. All of the systems selected were combinations of prefabricated components. Jointless bridges received very high rankings and are strongly recommended for the 60‐ft and 100‐ft span ranges. A precast voided slab system and a timber deck and steel stringer system received the highest ranking on the 30‐ft span range. This study proposed a method of selecting the type of bridge system to be built in a particular area and a priority scheme to select which bridges must be replaced first. The scheme models the Federal Highway Administration (FHWA) sufficiency ranking with some of the ranking ...

Field applications of prestressed laminated wood bridge decks

The concept of prestressing laminated wood bridge decks was conceived in Ontario in 1976 as a method of upgrading existing deteriorated nailed laminated wood decks. The success of this technique as a method of rehabilitation prompted considerable research and development aimed at introducing it into new construction. This work led to the formation of a comprehensive set of design specifications, which have since been adapted into the Ontario highway bridge design code and were included in the 1983 edition.Since its inception in 1976, the prestressed wood concept has been used many times, and by 1985, more than 16 bridges incorporated the concept in various ways. The objective of this paper is to discuss a number of these field structures in order to demonstrate the flexibility of the prestressed wood deck system. In new construction, the system has been applied to both longitudinally and transversely laminated decks including on-site deck assembly as well as a preassembled deck panel system.The paper describes the applicability of the system, construction sequence, and field problems. In addition, construction costs for some of the applications, as derived from field data, are discussed. Key words: wood, bridges, prestressed wood decks, laminated decks, preassembled deck panels.

Lateral Load Distribution in Multi-girder Bridges

This study of the distribution of internal forces in bridge structures is motivated in part by the sense that simple formulations may be perhaps inaccurate, restrictive and uneconomical in the design process. In the age of computerized structural analysis, the differences between the results of so-called exact, and now less costly, analyses and simplified load distribution rules are apparent. The availability of a variety of structural analysis systems programs greatly expands the options available to the bridge engineer. For slab and longitudinal girder bridges, a structural solver which will handle a three-dimensional frame combined with plate and shell finite elements can produce an "exact" analysis. SAP, NASTRAN, FINITE, ANSYS and SAP80 are examples of this type of program. These systems are implemented on machines ranging from supercomputers to desktop microcomputers. Programs such as SAP80 are accessible to the individual engineer on a personal, not corporate basis. However, the size of the problem and the range of analytical refinement available to the PC is restricted at present. Some level of simplification is needed, but even so considerable refinement over the present distribution rules can be achieved. Application of the analysis system does not involve the development of new computer programs—rather an application of an input "language" to the task of describing the loads and structure for analysis. Important also is a clear understanding of the idealization and specific structural theory underlying the system to be used. Once a paradigm input is written, the solution for a family of bridge types is usually simple. This paper provides an overview of insights gained on idealization and simplification for analysis and selected illustrative results developed on AISI Project 332, "Lateral Load Distribution for Multigirder Bridges." Detailed information will become available in the project final report. Discussed are structural idealizations of the bridge and deck systems accomplished by use of (1) the "exact" idealization of a shell bending element (RFSHELL) with axial membrane forces placed eccentric to the girders and diaphragm elements, (2) the grid with plate bending elements (RPB12) and (3) the simple grid for which both the transverse effect of the deck and composite action are taken into account (GRID). Selected results will be used representing simple and continuous bridges with a variety of span lengths, widths, number of girders and slab thicknesses.

AN EXPERIMENTAL STUDY ON SFRC COMPOSITE STEEL DECK

Composite steel deck system with Steel Fiber Reinforced Concrete (SFRC) has been developed, aiming to improve the durability of deck pavement and the rigidity of steel deck on highway bridges.The durability of SFRC was clarified through the static and cyclic loading tests using a full scale test bridge, and the measurements were taken on an actual highway bridge in order to confirm its composite effects.Consequently, it became clear that the structure showed composite behavior with high rigidity not only in floor system but also in main structural system.

On Modular Full Depth Bridge Deck Rehabilitation

Bridge deck systems consisting of a series of full depth precast concrete slab panel modules laid on steel stringers have been used for construction of new bridges as well as for rehabilitation of deteriorated bridge decks since at least the early sixties. Rapid construction is the main incentive of such construction method, which has been used for highway as well as for railway bridges, at a number of locations in the US and overseas. Prior to 1973, the application of full depth panels in the US were limited to noncomposite deck spans. A brief summary of essential features of these bridges are given. The emphasis of the paper is on the evolution of the application of the method since 1973 to date, which includes primarily composite spans and a number of major bridges. Various connection details and joint materials used in a number of bridges built by over half a dozen transportation agencies, using full depth precast panel are examined. Some of the persisting problems and uncertainties in using this meth...

Integration of Advanced Displays, FMS, Speech Recognition and Data Link

This paper outlines some of the results being achieved by the UK research programme on civil avionics which is based at RAE Bedford. Acknowledgments are therefore due to members of the civil avionics team and UK industry from whose work these examples are drawn, and not least to the Department of Trade and Industry who fund the programme.No attempt is made to define ‘flight management systems’. The concept, originating in the complex outer loops of autopilots, has now come to include all the detail involved in managing the flight deck systems as well as planning and controlling the aircraft's progress from ramp to ramp. As this paper will hope to demonstrate, the concept is still growing.

Horizontal deck systems in parallel hole cuts - a possible way of increasing the advance rate of tunnel drilling (in Swedish) : Orre, J Swedish Detonic Research Foundation reportDS 1983: 6, 15 Sept 1983, 31P

Horizontal deck systems in parallel hole cuts - a possible way of increasing the advance rate of tunnel drilling (in Swedish) : Orre, J Swedish Detonic Research Foundation reportDS 1983: 6, 15 Sept 1983, 31P

Deck Widening and Replacement of Woodrow Wilson Memorial Bridge

Several innovative construction techniques were used in replacing the deck of the Woodrow Wilson Bridge with lightweight precast concrete deck panels. Rehabilitation was completed 8 months ahead of schedule, $6 million under budget, and without disrupting the flow of traffic. This paper discusses the project in terms of traffic maintenance, design of the replacement deck system, precast concrete deck panels, polymer concrete applications, panel fabrication, and construction operations.

Wind tunnel experiments on the effects of turbulence on the aerodynamic behaviour of bridge road decks

Experimental results are presented for several different road deck systems including a truss system, a plate girder, and two box sections. The measurements have been made with a variety of test techniques including a full model in smooth and turbulent shear flow, taut strip models in smooth and turbulent flow and sectional models in smooth flow and grid generated turbulence. Comparisons are made between behaviour in the different flows and between two dimensional and three dimensional response.

Response of Taut Strip Models to Turbulent Wind

An experimental investigation was conducted to clarify the fundamental behaviour of the proposed taut strip wind tunnel model of long span bridge deck systems. The study shows that this method is relatively simple and convenient and yet effective method of investigating the aerodynamic behaviour of long span bridges with the simulation of natural wind turbulence in laboratory scale. Experimental results are compared with the simple theoretical calculation and some aerodynamic characteristics of bridge response in highly developed turbulent boundary layer flow were observed. Effect of scale of turbulence in particular is found to be significant.

NASA to begin construction of aviation‐safety test facility

Construction of a $7.5‐million facility to research aviation safety will begin in April at NASA's Ames Research Center in Mountain View, California. Scheduled for completion in 1983, the facility will give scientists their first opportunity to identify and study psychological factors involved in the relationship between pilots, crew members, and modern aircraft.The center will have two simulators. One will be a replica of a current transport airplane cockpit, complete with flight engineer's station, flight display, and control systems. The second will represent transport aircraft of the future. With advanced technology flight controls, displays, and other flight deck systems to accommodate a flight crew and observer, the advanced simulator will be designed to test human responses to the newest aviation technologies.

Future flight deck design

The greatly increased cost of fuel has intensified the need for the manufacturer to increase operating efficiency in the aerodynamic, structural and propulsion fields. These aspects have already been highly refined and further improvements will be more and more difficult to realise. However, DOC is also equally affected by equipment and crew costs and this paper therefore attempts to examine the potential for improvements to the flight deck that will determine the most cost-effective combination of crew and equipment required for the safe operation of relatively large transport aircraft.In the past, design effort has, very logically, been concentrated on those fields that could be shown to give an obvious economic return, and since investment in new instrumentation, flight deck workload analysis and system automation showed less tangible results than increases in speed, range, payload, etc, there was no great incentive to allocate money and effort to “human engineering”.