Abstract: For military and civilian applications, there exists a need for lightweight, inexpensive, short-span bridges that can be easily transported and erected with minimal equipment. Owing to its favorable properties, fiber-reinforced polymer (FRP) has been shown to be feasible for the construction of such bridges. Investigations into the behavior of a short-span bridge structural concept, adapted to the material properties of commercially available glass FRP (GFRP) pultruded products, are presented. A 4.8-m span prototype was built from GFRP sections, bonded throughout to form a tapered box beam, with a width of 1.2 m and a height at midspan of approximately 0.5 m. The box beam represents a single trackway of a double-trackway bridge, whose trackways could be connected by light structural elements. The quasi-static and dynamic behavior of the prototype box beam was investigated in ambient laboratory and field conditions to assess the design and construction techniques used, with a view to designing a full-scale 10-m GFRP bridge. Laboratory testing of the prototype box beam used single and pairs of patch loads to simulate wheel loading. These tests confirmed that the box beam had sufficient stiffness and strength to function effectively as a single trackway of a small span bridge. Field testing of the structure was undertaken using a Bison vehicle (13,000 kg), driven at varying speeds over the structure to establish its response to realistic vehicle loads and the effects of their movement across the span.

Abstract: The only cable-stayed bridge in Croatia, the Dubrovnik bridge, was opened for traffic in 2002. The main cable-stayed bridge with composite superstructure is jointed in span to the prestressed concrete approach bridge by a hinge-type connection. The bridge has experienced vibrations of cable stays under certain wind conditions, as with many other cable-stayed bridges around the world. After a short review of results of wind tunnel tests and various numerical analyses, field observations of cable-stay vibrations are highlighted. Only after extremely violent movements of cable stays and the superstructure under a heavy, damp snowstorm occurred, resulting in substantial damage, was it decided to apply vibration mitigation measures. Adjustable cable dampers, based on the latest MagnetoRheological (MR) technology, were installed on the bridge to raise low structural damping of the most affected cable stays.

Abstract: Laboratory study on the identification of moving vehicle axle loads on a multi-span continuous bridge from the measured bending moment responses is presented. A bridge-vehicle system model was fabricated in the laboratory. The bridge was modeled as a three span continuous beam and the car was modeled as a vehicle model with two-axle loads. A number of strain gauges were adhered to the bottom surface of the beam to measure the bending moment responses. Using measured bending moment responses as an input, the corresponding inverse problem was solved to identify moving loads. The moving forces were identified when considering bending moment responses from all spans of the beam. In order to avoid the lower identification accuracy around the inner supports of continuous bridge and to improve the computation efficiency, the moving force identification from the target (one selected) span of the continuous bridge was studied. The rebuilt responses were reconstructed from the identified loads as a forward problem. To study the accuracy of the method the relative percentage errors were calculated with respect to the measured and the rebuilt bending moment responses. The rebuilt bending moment responses obtained from the identified forces are in good agreement with the measured bending moment responses. This indirectly shows that the method is capable of identifying moving loads on continuous supported bridges.

Abstract: The resonance mechanism and conditions of the trainbridge system under moving trains are studied through theoretical derivations and example analyses.According to different mechanisms,there exist several types of resonance,including the bridge resonance induced by the periodical actions of moving load series of the weights,centrifugal forces and lateral winds of vehicles,the bridge resonance induced by the loading rates of moving load series of vehicles,the bridge resonance induced by the periodical loading of train vehicles excited by rail irregularities,wheel flats and hunting movements,and the vehicle resonance induced by periodical actions of the regular arrangement of bridge spans and their deflections.The resonance conditions of the train-bridge system are affected by the span,total length,lateral and vertical stiffness of the bridge,the compositions of the train,and the axle arrangements and natural frequencies of the vehicles.

Abstract: Morphing aircraft are a focus today due to their ab lity to combine multiple mission flexibility with a single vehicle. The Hyper-Ellip tical Cambered Span (HECS) wing is one such wing being developed as a testbed for morp hing technologies, due to its ability to vary the spanwise curvature in order to alter a craft’s lift-to-drag performance. Through analysis of the aft-swept wing geometry and review of theory, predictions of aerodynamic performance are benchmarked against qua i-static rigid wing models in the Cornell University low-speed wind tunnel facility. Models assume a discretized approximation of the continuously varying spanwise curvature, with system order reduced significantly via a spool-and-tendon mechan ism linking motions proportionally. The traditional rib-and-skeleton framework is repla ced by a composite structure more adept at withstanding compressive loads due to actu ation as verified through finite element analysis. Actuation methods are contrasted between a DC motor driven system and one employing shape memory alloy (SMA) wires, w hich generate proportional motion by linking sections electrically rather than mechanically. An energy comparison reveals the SMA wire to be more efficient, resultin g a prototype with embedded SMA wire actuators. The prototype employs a nonlinear proportional-integral controller to reach desired wing setpoints, which can be modified to user specifications based on flight conditions. A thermomechanical system model for th e SMA is detailed and implemented in the feedback law, which relates well to observed actuation. The prototype half-wing is dynamically tested over a range of angle of attack in the wind tunnel facility. Results confirm the hypothesis that the planar wing will pe rform better than an elliptical wing of comparable characteristics, while morphing to the ‘ furled’ state further increases lift-todrag only over a small range of angle of attack. T he SMA mechanism is demonstrated to be a viable means of morphing the wing, capable of overcoming aerodynamic loads and holding a desired wing shape based on the feedback law. Metrics of success are delineated and future revisions and inclusions are discussed.

Abstract: The original bridge opened in 1961, was designed by Mott Hay and Anderson as a conventional suspension bridge with symmetrical geometry, having a main span of 335m and side spans of 114m, and with anchorage and approach spans the overall length is 642m. Unusually for a suspension bridge of this era, the towers were constructed from reinforced concrete, and have a height of 73m with the deck suspended at half this height. The towers sit on caisson foundations founded on rock. Main suspension cables are 350mm in diameter and each consists of 31 locked coil wire ropes, and carries vertical locked coil hangers at 9.1m intervals. The stiffening truss is 5.5 metres deep and composed of welded hollow boxes.

Abstract: Systems and methods for auto-resetting span power protection are provided. In one embodiment, a method for deactivating a protective device is provided. The method comprises determining when an overload condition occurs on a communication medium; when the overload condition occurs, deactivating at least one protective device by applying, for a first predetermined period of time, a short-circuit to an output of a power supply that provides a holding current to the at least one protective device; and after the first predetermined period of time has elapsed, removing the short-circuit on the output of the power supply.

Abstract: The nonlinear span of a sequence x is defined as the length of the shortest feedback shift register that generates x. In this correspondence, we solve the problem of designing periodic binary sequences with given linear complexity and maximal possible nonlinear span. We concentrate on the case of sequences with period N=2n-1 and we introduce two construction methods

Abstract: The invention supplies a method to gain network time-out re-transferring time span that could gain the time span between gaining send request report and receiving the response report and calculate the time-out re-transferring time span. The invention also supplies a method for network data transferring that includes the following steps: sending request report; receiving response report; gaining the time span between the previous two steps; calculate the time span of time-out re-transferring; when transferring next data, sending request report according the time span. The invention could make the most of bandwidth and improve data transferring ratio.

Abstract: Multiple-span reinforced concrete highway overpass bridges constitute a large number of the total inventory of bridges in California, particularly bridges of new design. Performance of these bridges is therefore integral to the evaluation of transportation network performance under high intensity earthquake scenarios. Additionally, probabilistic quantification of bridge response and vulnerability will provide insight into the evaluation of current designs at different levels of seismic hazard. Performance of bridges at the demand, damage, and loss levels can be evaluated using the Pacific Earthquake Engineering Research (PEER) Center’s performance-based earthquake engineering framework. This paper illustrates probabilistic seismic bridge vulnerability evaluation using two typical single column-per-bent, five-span, post-tensioned box girder, reinforced concrete highway bridge types. The first bridge type has a straight deck and 22-foot columns of equal height above grade. The second bridge type has 50-foot high columns. Each bridge type has a variety of column configurations designed for different seismic demands typical for a variety of bridge sites in California. A complex model of the structures is created in OpenSees that accounts for nonlinear behavior of the columns, deck, abutments, and expansion joints at the abutments. This model is developed in a modular fashion to allow incorporation of improved soil models, models for emerging structural components, technologies, and use of new analysis methods. Seismic demand models are then developed using nonlinear time history analysis, including far- and near-field excitation. Damage in the columns is determined from a database of experimental tests and, finally, approximate repair cost ratios are estimated from the ascertained discrete damage states. Four bridge models are implemented for both types of bridges considered. The vulnerability of the base bridge types is presented in this paper as a benchmark with which to compare the use of enhanced performance structural elements and demands due to liquefaction and lateral spreading, when coupled with geotechnical models of the bridge-soil system.

Abstract: The determination of the statistical characteristics of bridge deflections due to a load of a vehicle moving across the span of a bridge is frequently a problem of great interest for bridge engineers. Developed herein is a spec- tral approach for evaluating the variation of bridge deflections due to a vehicle moving at constant speed along a rough bridge surface. Based on the above-mentioned approach, this study presents a closed-form solution for variances of bridge deflections. An example of application of the solution to the estimation of variances of bridge deflections is also presented. The effects of pavement type, vehicle speed, and bridge span on standard deviation of bridge deflections are investigated. The results of numerical examples show that if the effect of engine motions on vehicle vibrations is disre- garded, the standard deviation of bridge deflections is proportional to the square root of the pavement roughness coeffi- cient a for a specified vehicle speed.

Abstract: Stonecutters Bridge of Hong Kong is a cable-stayed bridge with two single-column pylons each 298 m high and an aerodynamic twin deck. The total length of the bridge is 1596 m with a main span of 1018 m. The top 118 m of the tower will comprise structural steel and concrete composite while the bottom part will be of reinforced concrete. The bridge deck at the central span will be of steel whilst the side spans will be of concrete. Stonecutters Bridge has adopted a twin-girder deck design with a wide clear separation of 14.3 m between the two longitudinal girders. Although a number of studies have been conducted to investigate the aerodynamic performance of twin-girder deck, the actual real life application of this type of deck is extremely limited. This therefore triggered the need for conducting the present studies, the main objective of which is to investigate the performance of Stonecutters Bridge against flutter at its in-service stage as well as during construction. Based on the flutter derivatives obtained from the 1:80 scale rigid section model experiment, flutter analysis was carried out using 3-D finite element based single parameter searching method developed by the second author of this paper. A total of 6 finite element models of the bridge covering the in-service stage as well as 5 construction stages were established. The dynamic characteristics of the bridge associated with these stages were computed and applied in the analyses. Apart from the critical wind speeds for the onset of flutter, the dominant modes of vibration participating in the flutter vibration were also identified. The results indicate that the bridge will be stable against flutter at its in-service stage as well as during construction at wind speeds much higher than the verification wind speed of 95 m/s (1-minute mean).

Abstract: Disclosed is a method of constructing partially earth-anchored cable-stayed bridges using a thermal prestressing technique, in which, when a steel girder-type partially earth-anchored cable-stayed bridge is built using a cantilever construction technique, the center of an intermediate span of the bridge is closed with a final key segment using a thermal prestressing technique, thus applying an initial axial tensile force to reinforcing girders of the bridge. To apply the initial axial tensile force to the reinforcing girders while the center of the intermediate span is closed with the final key segment, an appropriate space length required for closure of the final key segment is determined, and both the heating region and the heating temperature of the reinforcing girders according to the initial axial tensile force to be applied to the reinforcing girders during a process of manufacturing the final key segment are determined. Thereafter, the reinforcing girders are heated using a heating means according to the above-determined conditions, thus being thermally lengthened to predetermined lengths corresponding to the predetermined space length. The junction between the reinforcing girders at the center of the intermediate span is closed with the final key segment and, thereafter, the heating means is removed from the reinforcing girders.

Abstract: During initial start-up of an optical communication system, an ASE reference span loss is calculated based on transmitting power and received power of ASE light generated by an optical amplifier, and an OSC reference span loss is calculated based on the transmitting power and the received power of OSC light. During normal operation of the optical communication system, a span loss is calculated using the OSC light, and an amount of change in the span loss representing a difference between the span loss and the OSC reference span loss is calculated. A current span loss between a transmitting station and a receiving station is calculated by adding the amount of change in the span loss to the ASE reference span loss.

Abstract: For the sake of timely appraising the working condition of the bridge, measuring the dynamic characteristics of the bridge structure is very important and necessary. A GPS dynamic monitoring test was carred out in the Wuhan Baishazhou Bridge, which is one of the longest span cable-stayed bridges having been built in China. This paper introduces the experimental implementing scheme and data processing method. The vibration characteristics of the middle span of cable-stayed bridge are availably obtained by use of the spectral analytic approach. The measuring results are very identical to the theoretical designed values. The research demonstrates that, with GPS receiver of the high sampling rate and suitable data processing method, the vibration characteristics of the bridge structure can be determined with high accuracy.

Abstract: Structural Bridge Deck Overlay (SBDO) involves applying 6 to 10 in. (150 to 200 mm) of normal weight, class AA, reinforced concrete directly to a bridge's original slab. The overlay is designed to increase the deck elevation to an extent that standard highway resurfacing procedures can continue uninterrupted up the edges of the bridge. Otherwise, excavation along the bridge approaches or jacking of the superstructure is required to insure proper elevation. Experimental static field tests were conducted on three different bridges: (1) Simply supported prestressed concrete I-girder bridge; (2) cast-in-place reinforced concrete continuous haunched girder bridge; and (3) cast-in-place reinforced concrete simple span bridge. Field tests were conducted prior to the concrete overlay process and following the application of the concrete overlay. Based on the results obtained in this research study, a significant advantage is noted due to the additional deck thickness. The addition of the SBDO increases the load carrying capacity of the bridge in addition to providing a wider bridge deck and new and code compliant barrier walls.

Abstract: Embodiments of a fluid storage and introduction device (20) constructed in accordance with respects of the present invention are provided. One embodiment of the device (20) includes an inner assembly (24) and an outer housing (26). When assembled, the device (20) is securely coupled to a cable or cable section (30) along a portion of its span. In use, the device (20) is capable of storing remediation fluid and introducing such fluid into the cable or cable section (30).

Abstract: The invention relates to a side-open container for increasing the span of opening door, which comprises a basic support, an angle post mounted on the four angles of basic support, a top side beam connecting two angle posts on one side of basic support, and a side-open door mounted on the side surface of box and between the basic support and the top side beam. Wherein, said side-open door comprises a rotational door and a sliding door. The invention can increase the stability, the safety of matters, the span of open-door, and when the matter has bigger size, the sliding gate can move longitudinally to apply detachment.

Abstract: An optical fiber monitoring system was designed and built into one span of the five span high performance prestressed concrete I-10 Bridge over University in Las Cruces, NM. A total of 72 long-gage (2m long) deformation sensors, along with 36 thermocouples were embedded in the prestressed concrete girders. Sensors were installed along the bottom and top flanges, at mid-span and quarter spans. Pairs of crossed sensors in a rosette configuration were embedded in the webs at the supports. The embedded sensors measured temperature and deformations at the supports, quarter spans, and mid-span. Data was collected from the start of construction thru service. Collected data was analyzed to evaluate the prestress losses and cambers in the girders. Actual losses and camber were compared to the losses and camber predicted using available code methods. The project was funded by the New Mexico DOT and the FHWA under the Innovative Bridge Construction Program.

Abstract: The AASHTO-LRFD (2004) live load distribution factors for highway bridges show significant change compared to the standard AASHTO (1996) that have been used for the last 50 years. This paper presents a comparison between the moments distribution factors of concrete bridges due to live load calculated in accordance with the current AASHTOLRFD (2004) formulas and finite-element analysis. Several three-dimensional linear elastic models were built using the structural analysis program SAP2000 (2004) to obtain the most accurate method to model the bridge superstructure. The bridge deck was modeled as quadrilateral shell elements and the girders as space frame elements. The live load used in the analysis is the vehicular load plus the standard uniform lane load as specified by AASHTO–LRFD (2004). The live load is positioned at the longitudinal location that produces the maximum moments, then the load is moved transversely across the bridge width in order to investigate all possibilities of bridge loading (one, two and three lanes loaded). In this comparison the range of applicability specified by the AASHTO-LRFD (2004) is fully covered in terms of span length, slab thickness, girder spacing and longitudinal stiffness. One parameter is considered at a time while the remaining parameters are fixed. All the AASHTO-PCI girders (Type I to VI) are considered to cover the complete range of longitudinal stiffness specified in the AASHTO–LRFD (2004) specifications. The results of this study are presented in format of graphs and some recommendations for specific bridge geometries are presented.

Abstract: An infinite periodic structure is usually modeled using a single span with appropriate periodic conditions. If a large finite periodic structure with N spans behaves like an infinite periodic structure, then, here also a single span model will suffice giving cost savings in computation. This paper is about such a meeting point between infinite and finite periodic structures. The propagation constant of an infinite periodically supported beam is obtained analytically from the response of a finite periodically supported beam. In an infinite periodic beam, e g (g is the complex propagation constant) is the ratio of velocities in any two neighboring spans and is obtained using a single span model. Here, it is shown (analytically and experimentally) that if the finite periodic beam has enough spans, then eg computed from the first two spans will match eg for an infinite periodic beam in the attenuation zones.