Showing papers on "Span (engineering) published in 1987"
TL;DR: In this paper, the PCI Design Handbook, Section 5.2.9, Lateral Stability, briefly describes the problem and suggests solutions, and Ref. 4 is the basis for this section.
Abstract: n the early history of the prestressed concrete industry (up to 1960), bridge beams were very bulky (heavy) and their length seldom exceeded 100 ft (30.5 m). In fact, at that time, 80 ft (24.4 m) beams were considered quite long. With advancing prestressing technology, together with the improvement of materials (especially high strength concrete and high strength prestressing steels), beam sections became progressively more structurally efficient. As a result, beam sections became more slender and the spans much longer. Currently, on the West Coast, 148 ft (45.1 m) beams are common and 130 to 140 ft (39.7 to 42.7 m) bulb T beams and I beams are used frequently. Today, the length limit of bridge members is determined mainly by the mode of transportation (truck steering trailer) and allowable gross weight rather than any arbitrary span restriction. Over the years, as beam sections became more slender and their spans longer, producers soon discovered that these long beams had a tendency to crack or even collapse during handling or shipping unless the lifting points (shipping points) were moved away from the ends of the members, or special braces were attached to the beam. The lateral stability of these types of beams was discussed in the 1960s (see Refs. 1, 2 and 3). Further information on this topic may also he found in Refs. 4 and 5 (published in 1971). Currently, the PCI Design Handbook, in Section 5.2.9, Lateral Stability, briefly describes the problem and suggests solutions. Ref. 4 is the basis for this section. Lateral instability occurs during the handling and shipping of long prestressed bridge beams. This problem arises because of the imperfections
35 citations
Patent•
21 Oct 1987
TL;DR: In this paper, a blade assembly is created featuring pivotally mounted first and second blades with pivot and subsequent change the span of each blade in response to the amount of shaving force generated by the user.
Abstract: According to this invention a blade assembly is created featuring pivotally mounted first and second blades with pivot and subsequent change the span of each blade in response to the amount of shaving force generated by the user.
25 citations
Patent•
25 Sep 1987
TL;DR: In this article, the approach and main spans of a cable-stayed segmental bridge are constructed as a smooth continuation of the approach spans without the need for special equipment or different box girder deck sections.
Abstract: A method of constructing the approach and main spans of a cable stayed segmental bridge as the main span is constructed as a smooth continuation of the approach spans without the need for special equipment or different box girder deck sections. The approach spans are constructed each in succession from opposite sides of the main span after which the main span continues from opposite sides toward a midpoint, while the cable stays are installed. For a two-wide box girder bridge, delta frames interconnect side-by-side box girders at the anchor locations of the cable stays for thereby transferring the static and dynamic loads of the main span toward the center plane of support of the cable stays.
22 citations
Patent•
7 May 1987
TL;DR: In this article, an interlock grate structure is provided which includes longitudinal load bearing span bars having lateral locating holes spaced there along for receiving transverse tie bars, the transverse ties bars having axial locking means which engage the longitudinal span bars at the point of juncture to prevent axial displacement of the tie bar relative to the span bar.
Abstract: An interlock grate structure is provided which includes longitudinal load bearing span bars having lateral locating holes spaced therealong for receiving transverse tie bars, the transverse tie bars having axial locking means which engage the longitudinal span bars at the point of juncture to prevent axial displacement of the tie bar relative to the span bar. A longitudinal lock rod serves to interlock the position of the transverse tie bar locking means with respect to the longitudinal span bar.
21 citations
Patent•
23 Jul 1987TL;DR: In this paper, the authors proposed a priority scheme for multi-channel, multi-site communications system, where spans on working channels extending in an overlapping manner among the sites are afforded protection by a protection channel.
Abstract: In a multi-channel, multi-site communications system, spans on working channels extending in an overlapping manner among the sites are afforded protection by a protection channel in accordance with a priority scheme. Enabling of protection switching for each span in the event of a signal failure on the span is dependent upon whether there is any protection higher priority overlapping span. This is determined individually for each span in response to each change in protection requests in the system.
14 citations
TL;DR: In this article, the authors describe an experimental study into the overall influence that the end region of a flap has on the flow of a high lift wing system, focusing mainly on the tip flow of the flap itself.
Abstract: The work to be described forms part of an experimental study into the overall influence that the end region of a flap has on the flow of a high lift wing system. Here, our attention will be restricted mainly, but not entirely, to the tip flow of the flap itself. The study has been a collaborative venture over the past three years between British Aerospace-Civil Aircraft Division and the Aerospace Engineering Department of Bristol University, the latter funded by an SER.C research grant. BAe's major contribution was the undertaking of the main test programme, with University participation, using a large swept wing, high lift half model in the Filton low speed wind tunnel. The model was loaned by RAE for the study.
6 citations
Patent•
2 Sep 1987
TL;DR: In this article, a cable-stayed bridge pier for bearing the bridge span is proposed, which is composed of a pretension inclined bar, an inclined bar anchoring pier and a flexible pier body which is flexible in longitudinal direction and rigid in transverse direction.
Abstract: The utility model relates to a flexible cable-stayed bridge pier for bearing the bridge span, which is composed of a pretension inclined bar, an inclined bar anchoring pier and a flexible pier body which is flexible in longitudinal direction and rigid in transverse direction. The utility model utilizes the increase-decrease change values of the tensile force of the pretension inclined bar to bear the braking force and reduce the section of the bridge pier. The utility model which makes full use of the strength of material maintains the stress state of a freely supported beam and a supporting base of the freely supported beam, has reasonable structure, and is favorable for laying the jointless track on bridges.
5 citations
Patent•
27 Feb 1987
TL;DR: In this paper, a high bearing span (clearance) ratio was used for the deep drawing of motor-vehicle body components, with a strong elastic layer 10 of uniform thickness.
Abstract: Deep-drawing tool having a high bearing span (clearance) ratio, of the type constituted by a punch 2, a die 4 and upper 6 and lower 8 blank holders, at least one of which is covered, on its active part, with a strong elastic layer 10 of uniform thickness. Application: especially to the deep drawing of motor-vehicle body components.
4 citations
Patent•
22 Jan 1987
TL;DR: In this article, a shape memory alloy spring is mounted to a centrifugal weight contained in a timer housing to improve starting properties of an internal combustion engine, where the driving force is inputted from an internal-combustion engine.
Abstract: PURPOSE:To improve starting properties, by a method wherein a shape memory alloy spring is mounted to a centrifugal weight contained in a timer housing CONSTITUTION:Centrifugal weights 19 are contained in a timer housing 1 to which a driving force is inputted from an internal-combustion engine A guide rod 23 is extended through in a manner to span between the centrifugal weights 19, and end part spring support seats 25 are mounted to both ends of the guide rod through their respective lock rings 24 a shape memory alloy spring 26 is spanned between the end part spring support seat 25 and the centrifugal weight 19 When temperature is decreased to lower than a give value, the centrifugal weight 19 is displaced to the lead angle side This enables improvement of starting properties
4 citations
Patent•
11 Dec 1987
TL;DR: In this paper, a dielectric belt cleaning system includes counter-rotating pairs of adjoining cylinders mounted to a housing, where residual toner is dislodged and drawn through a low pressure zone between each pair of cylinders leading to a filtered discharge outlet.
Abstract: In an electrographic printing apparatus, a dielectric belt cleaning system includes counter-rotating pairs of adjoining cylinders mounted to a housing. A vacuum source forces the dielectric belt in free span against the surfaces of the cylinders which are covered by a directional raised nap. Residual toner on the belt is dislodged and drawn through a low pressure zone between each pair of cylinders leading to a filtered discharge outlet. The brushes are cleaned by their interengagement along adjacent cylinder surfaces where the cylinder brushes mesh and also between each cylinder brush and a rake therefor fixed to the housing.
TL;DR: In this paper, the adequacy of the length scale-down (LS) span as a tool for predicting the performance of the full span of transmission line conductors is established. But the LS span is not considered in this paper.
Abstract: Length scale-down (LS) model tests have been traditionally employed for laboratory studies on aeolian vibration of transmission line conductors. The span adopted is normally 30 m and is recommended by the relevant Indian, as well as other, standards. The traditionally adopted length of the LS model is reexamined herein to establish the rationale behind the choice. Based on the theoretical studies discussed, certain guidelines for the choice of model span of conductor are emphasized. In addition, the adequacy of the LS span as a tool for predicting the performance of the full span is reestablished.
Journal Article•
1 Jan 1987
TL;DR: The first S-curved cable-stayed bridge in the world has been completed as a part of the Metropolitan Expressway's Katsushika-Edogawa Route in Japan as discussed by the authors.
Abstract: Just recently, in January of 1987, the first S-curved cable-stayed bridge in the world has been completed as a part of Metropolitan Expressway's Katsushika-Edogawa Route in Japan. The bridge has a four span continuous curved girder, two main towers and multiple cables. The total length is 455 meters (40. 5 m plus 134 m plus 220 m plus 60. 5 m) and the towers' heights are 65 m and 29 m respectively. The structural and constructional features are given.
Patent•
28 Feb 1987
1 Apr 1987
TL;DR: The concept of span of metric spaces was introduced by Lelek [5] and is an important concept in regard to chainability of continua as discussed by the authors, and it has been shown that zero span is a sequential strong Whitney reversible property.
Abstract: The concept of span of metric spaces was introduced by Lelek [5]. Span is an important concept in regard to chainability of continua. In this paper, motivated by recent results [2, 11], we show that zero span is a sequential strong Whitney-reversible property.
Patent•
2 Jun 1987
TL;DR: In this paper, a support system for a multiple-span bridge constructed of reinforced concrete or prestressed concrete includes a primary structure and a secondary structure, consisting of serially arranged individual roadway sections extending in the long direction of the bridge.
Abstract: A support system for a multiple-span bridge constructed of reinforced concrete or prestressed concrete includes a primary structure and a secondary structure. The primary structure bridges the spans between intermediate supports or between an abutment and an adjacent intermediate support and includes serially arranged support members elongated in the long direction of the bridge. The width of the support members is a fraction of the full useful width of the bridge. The secondary structure forms the roadway slab and is supported on the primary structure. The secondary structure is made up of serially arranged individual roadway sections extending in the long direction of the bridge. The roadway sections are supported by bearing members resting directly on the support members of the primary structure with the roadway sections being closely spaced in the elongated direction of the bridge as compared to the spans between the intermediate members and the abutments. The roadway sections extend over the expansion joints between the support members. The roadway sections can have a dimension in the elongated direction which is comparable to that of the support members or which is a multiple of the length of the support members. The support members can be constructed in place on the bridge, while the roadway sections can be constructed at a single site and then moved over the support members into their final position on the bridge.
1 Jan 1987
TL;DR: In this paper, theoretical expressions derived from buffeting theory were derived for calculating wind load on a cable-stayed bridge during construction and compared with aero-elastic model data for the main span of the Annacis Island Bridge, Vancouver.
Abstract: Some of the dominant loadings on a cable-stayed bridge during construction are a result of the non-uniform vertical and horizontal gust forces on the deck and the associated dynamic response of the structure. This paper gives theoretical expressions, derived from buffeting theory, for calculating these forces and compares the results with aeroelastic model data for the 465m main span Annacis Island Bridge, Vancouver. The expressions are in a form that can be relatively easily used and they are put forward as a design tool to examine wind loading during development of the construction sequence.
TL;DR: In this article, a software system is developed to analyze and rate existing bridges, including truss and continuous girder bridges up to three spans, and a wide variety of output related to bridge behavior is available.
Abstract: A software system is developed to analyze and rate existing bridges. The system is capable of rating simple truss and continuous girder bridges up to three spans. Composite and noncomposite steel girders and concrete T-beam bridges are supported. Girder bridge cross-sectional properties may vary along each span. Five standard American Association of State Highway and Transportation Officials (AASHTO) trucks and one user-defined truck are supported. The analysis methods selected are chosen to minimize computer resources. A wide variety of output related to bridge behavior is available. Two examples, a two-span girder bridge and a four-panel Pratt Truss bridge, are presented. Identical results are obtained from microcomputers with 8088 or 80286 processors. However, the microcomputers with the 80286 processors conducted the analysis and rating approximately 2.5 times faster. For the 80286-based microcomputers, the run time for the two-span bridge varied between 1 minute 12 seconds and 2 minutes 52 seconds. With the proper software, microcomputers will assist those individuals responsible for inspecting and rating the approximately 570,000 bridges in the country.
Patent•
2 Nov 1987
TL;DR: In this article, a calibration system for a mechanical gas volume corrector with a first shaft turning at a rate corresponding to the otherwise uncorrected volumetric flow rate through the meter, a second shaft, a variable ratio transmission coupled between the first and second shafts, and means for altering the ratio of the transmission in response to changes of a physical condition of the gas.
Abstract: A calibration system for a mechanical gas volume corrector which has a first shaft turned at a rate corresponding to the otherwise uncorrected volumetric flow rate through the meter, a second shaft, a variable ratio transmission coupled between the first and second shafts, and means for altering the ratio of the transmission in response to changes of a physical condition of the gas. The calibration system includes means for applying a representation of a reference state of the physical condition to the ratio altering means, means for indicating a fixed number of revolutions of one of the shafts, means for determining the number of revolutions of the other of the shafts corresponding to the fixed number of revolutions of the one shaft, and means for determining and displaying the ratio of the other shaft revolution number to the fixed number. The calibration system also includes an adjustment mechanism for changing the zero setting and the span (or gain) of the ratio altering means.
TL;DR: In this article, the analytical equations of equilibrium for a nonsymmetrical bridge with inclined legs, using the slope deflection method which is valid when the influence of axial forces on the various parts of the bridge is taken into account, are presented.
Patent•
4 Aug 1987
TL;DR: In this paper, a modular bridge is designed to span gaps of the order of 10 to 60 m without intermediate support, characterised in that it consists of: a number of modules 10, 10', transportable using ordinary lorries, each module comprising two main beam units 14, 16 each containing one launching beam unit 18, 20 which can slide in the matching main beam unit, the modules being provided with means for assembling and locking together, on the one hand, the main beams and on the other hand the launching beams; a launching system 32 designed to project an advance
Abstract: Modular bridge designed to span gaps of the order of 10 to 60 m without intermediate support, characterised in that it consists of: a number of modules 10, 10', transportable using ordinary lorries, each module comprising two main beam units 14, 16 each containing one launching beam unit 18, 20 which can slide in the matching main beam unit, the modules being provided with means for assembling and locking together, on the one hand, the main beams and, on the other hand, the launching beams; a launching system 32 designed to project an advance bridge over the gap to be covered and consisting of an assembly of a sufficient number of main beams; a motorised system allowing a set of launching beams, sufficient in number to reach the far bank, to be advanced along and inside the advance bridge, the set of main beams forming the bridge then being moved in translation along the set of launching beams until it comes to rest on the far bank and in this way totally covers the gap.