Abstract: This paper presents distribution factor expressions for wheelload distribution to interior and exterior girders of concrete on multisteel beam composite bridges of medium span length. These express...

Abstract: In a traveling inspection robot system, two carriages are each provided with one pair of guide rollers for guiding the travel in the vertical direction and two pairs of side rollers for guiding the travel in the horizontal direction. The two pairs of side rollers are arranged such that one pair locates on each of the front and rear sides of the pair of guide rollers as viewed in the direction of advance. The two carriages are interconnected by a coupling plate through parallel steering shafts, and a sprocket and a motor for driving the sprocket are provided as travel driving device on one carriage for giving a traction force to a transversely central portion of the upper inner surface of the monorail. An antenna and a current collector are provided on the other carriage. A control circuit unit and a span and tilt mechanism are attached to the coupling plate with a sensor unit mounted to the span and tilt mechanism. A swing motor and a tilt motor in the span and tilt mechanism are arranged in respective dead spaces created when the span and tilt mechanism swings and tilts. A chain, a trolley line and an antenna line are laid and wired on the upper inner surface of the monorail. With such an arrangement, the degree of freedom in rail design can be increased, the robot and the monorail can be both made small in size, and therefore the applicable range of the traveling inspection robot can be enlarged.

Abstract: This paper presents a method for determining the dynamic impact factor of horizontally curved steel box‐girder bridges under vehicle loadings. The two‐dimensional planar grid analogy is used to model box bridges. The vehicle is idealized as a pair of concentrated forces, with no mass, traveling, on circumferential paths with constant velocity. Analysis of multigirder and continuous span bridges indicates a tendency for frequency clustering. Static solutions for these bridges are compared against mode superposition and direct integration. The bridge behavior was studied under several truck loading paths. Static and dynamic bridge behavior was observed under these loadings. A rational methodology for determining the impact factor is developed, and alternate impact‐factor criteria are proposed to replace the current American Association of State Highway and Transportation Officials guide specification.

Abstract: The invention relates to a flexible tubular conduit having at least one tubular layer constituted by at least one molded strip of a cross section substantially in the form of an elongated S, wound helically and having a cross section formed of a first and of a second principal cylindrical coaxial spans joined together by an inclined central portion, each of the first and second principal cylindrical spans being united by a first convex radial portion to a first secondary cylindrical span and by a second convex radial portion to a second secondary span. The second secondary span comprises a section connecting to the second convex radial portion (9), an end section (12) and a like intermediate section (13) whose concavity is turned away from the second principal span (6), and the second secondary span (12, 13) is arranged such that, when the strip is in the wound state, the connecting section is thrusting against the first principal span (5') of an adjacent spiral, and the end section (12) applies itself to the said first principal span (5')

Abstract: The results of an experimental investigation of the effects of span length disorder on the dynamics of mono-coupled, multi-span beams are reported. Two experimental specimens are considered: a nominally periodic 12-span beam with equal spacing between simple supports, and the corresponding disordered beam which features randomly spaced supports. Experimental results demonstrate that the transmission of vibration which takes place within the frequency passbands of the periodic beam is greatly hindered when span length randomness is introduced. The spatial localization of both the mode shapes and the steady state harmonic response to an end excitation is observed in the disordered 12-span beam, especially for frequencies which lie within the second passband. Very good quantitative agreement is obtained between experimental results and theoretical findings for both ordered and disordered configurations. Furthermore, an experimental estimation of the localization factory yields satisfactory agreement with the theoretical result for an infinite multi-span beam. This work reports one of the first systematic experiments carried out to demonstrate the occurrence of vibration localization in nearly periodic structures.

Abstract: A jig for assembling a rebar pier cage wherein certain of the individual jig elements are laterally and longitudinally adjustable to provide a jig capable of assembling rebar pier cages of various sizes and shapes. The jig elements comprise a plurality of rebar stirrup retaining elements removably secured within longitudinal openings in first and second, elongated channel bars which traverse a rectangular work surface in parallel relationship. Opposite ends of the first and second channel bars are slidingly secured within longitudinal openings of third and fourth channel bars which laterally span the opposite, shorter edges of the work surface. Means are provided to adjust the longitudinal spacing between each stirrup retaining element in the first and second channel bars, and also the lateral spacing between the first and second channel bars. The work surface is pivotally connected to a table frame whereby the work surface may be moved between horizontal and vertical positions with respect to the table frame and floor.

Abstract: An aircraft wing having a super critical profile is equipped with a venting device extending in the direction of the span width along the upper side of the wing. The ventilating device includes a compensation chamber in the wing and the chamber is covered with a perforated wall strip on both sides of the compression shock. The forward end of the compensation chamber has a gap shaped exit for blowing out the venting medium in the flow direction of the flow across the wing tangentially to the wing.

Abstract: Vibration and impact due to multiple vehicles moving across rough bridge decks are studied in seven steel multigirder bridges with different span lengths. The bridges are modeled as grillage beam systems. The vehicle is simulated as a nonlinear vehicle model with 12 degrees of freedom according to the HS20-44 truck design loading specified by AASHTO. Four classes of road surface roughness generated from power spectral density function for the approach roadways and bridge decks are used in the analysis. The results indicate that the impact of exterior girders of short-span bridges are highly sensitive to lateral loading position, vehicle weight, road roughness, and so forth. Maximum impact factors of girders were obtained for two trucks (side by side) through changing their transverse positions, with different speeds and road surface roughness. Results are useful for the bridge design and the further study of impact formula proposed by AASHTO.

Abstract: Analyses of field ambient vibration were performed on 50 concrete bridge spans along Interstate highways I-5 and I-405 in Washington State. These 50 spans included 21 pretensioned concrete beam (PCB) spans, 19 reinforced concrete box-girder (CBOX) spans, and 10 reinforced concrete slab (CS) spans. Eight measurement transducers were used to record ambient bridge vibrations at three locations on each span: midspan, one-quarter point, and one support. These records of bridge motion versus time were each subjected to a fast Fourier transformation, and plots of amplitude versus frequency were generated for each record. The plots of amplitude versus frequency were used to determine the fundamental vertical and lateral frequencies for the bridge spans measured. These fundamental frequencies were used with the bridge design parameters to derive empirical formulas that will be used to estimate the fundamental vertical and lateral frequencies of other PCB, CBOX, and CS bridge spans along I-5, I-205, and I-405 in the Pacific Northwest.

Abstract: In the study of wind-induced motion of conductors of overhead power transmission lines, an indoor test span measuring 30m or more is normally used. The span is generally excited into motion by an electrodynamic-type exciter connected at a span end. This connection increases the stiffness of the span at the point of connection, which will affect the dynamic characteristics of the test span. A more exact simulation of the indoor test conductor motion is essential. Simulation of test-conductor motion using the principle of electrodynamic forces between parallel, long conductors is proposed. Indoor test-span motion by this method is equivalent to steady crosswinds excitation in the field as distinguished from galloping conductors resulting from a combination of wind direction, velocity, moisture, and temperature. Consequently, the results of vibration experiments also will be more exact. The principle employed in the new excitation system, the methods of excitation in indoor spans using the principle, and the advantages of the new excitation system as compared to the presently employed system are discussed in this paper.

Abstract: This paper describes a full scale implementation of an active vibration control system on a 250 foot span steel truss highway bridge. An adaptive modal filter based modal control scheme is utilized in conjunction with a prototype long stroke electromagnetic reaction mass control actuator to achieve up to 20 db attenuation of modal response amplitudes. >

Abstract: The dynamic response of long-span cable-stayed bridges due to moving traffic loads is investigated utilizing three-dimensional models. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept, presented by discretization of cable into several elements in the finite element modeling, is used to study the effect of cable vibration on bridge dynamics. A computer algorithm is developed to simulate the applied traffic loads in both directions of the bridge deck. The algorithm is flexible in terms of handling different loading capacities, speeds and configurations. Parametric studies are conducted to investigate the effect of cable vibration, damping, vehicle-structure interaction, random roughness of the bridge deck, as well as span length and vehicle-speed. Cases of asymmetric traffic loading clustered in one direction are also considered in order to study the torsional response of the bridge. Results are discussed and summarized.

Abstract: Symmetry conditions are tabulated that must be fulfilled by all minimal balance surfaces, i.e. by all 3-periodic intersection-free minimal surfaces that subdivide R 3 into two congruent regions. The 52 configurations of straight lines (2-fold rotation axes) that may be embedded within any 3-periodic intersection-free minimal surface are described in some detail and surface patches for minimal balance surfaces that span these line configurations are discussed. Crystallo-graphic formulae for the calculation of the genera of 3-periodic intersection-free minimal surfaces are given. A list of all minimal balance surfaces known so far contains the respective inherent symmetries, the genera and in addition the orders, the site symmetries and the Wyckoff positions of their flat points.

Abstract: A network interface unit interconnected between a network span and a customer premises. The network span includes network transmit lines and network receive lines. The network interface unit includes a passive resistance circuit in the receive direction path that allows monitoring of signals from a central office in the presence of open circuit reflection or noise from the customer premises.

Abstract: PURPOSE:To reduce a bending moment to be applied to bolts and improve durability of the bolts in a connecting rod wherein a large end which is divided into two is fastened by means of the paired bolts, and positione by a pair of knock pins. CONSTITUTION:A large end 4 of a connecting rod 1 can be divided into a rod main body 7 and a cap 8. Both members 7, 8, sandwiching a large bearing port 6 on both sides in a widthwise direction, are fastened by a pair of bolts 9. The rod main body 7 and the cap 8 are positioned by a pair of knock pins 12 arranged adjacently to the bolts 9. An axis of each knock pin 12 is arranged nearer the large bearing port 6 than an axis of each bolt 9. Namely, a span S1 of the knock pin 12 is sat smaller than a span S2 of the bolt 9. A bending moment generated at a large end 6 is received by the knock pins 12, so that the bending moment applied to the bolts 9 is reduced.

Abstract: PURPOSE: To dispense with an expansion joint in a multiple span floor slab bridge, and to continuously provide a floor slab concrete and an asphalt pavement over the whole length of the multiple span floor system bridge. CONSTITUTION: In a multiple span floor slab bridge where a floor system bridge composed of an end part concrete 15 and a floor slab concrete 8 which are placed on a steel beam 4 and the upper face of the bottom plate 4c of the steel beam 4 and united with the steel beam 4 is supported on a bridge pier 1 in every span, hard rubber supports 2, 3 are severally used for the fixed and the movable shoe of the adjacent floor slab bridge supported on a common bridge pier 1. The opposite end parts of the adjacent floor slab bridges are mutually joined through a connecting arm 6 with pin bolts 9. the floor slab concrete 13 is placed over the mutual upper faces of the upper flanges 4a of the steel beams 4 at the the adjacent floor slab bridge ends. COPYRIGHT: (C)1994,JPO

Abstract: From experiences and laboratory tests it can be seen that the sag increases considerably during the operational period of overhead transmission lines. Because of lack of knowledge of this fact, the changes of sag is not always taken into calculation in the phase of planning. The authors show how the results of long-time creep strain measurement in the laboratory can be used in planning of overhead transmission lines. An example illustrates how the alteration in sag caused by conductor creep is dependent on the span length. The increases in sag are extrapolated for an operational period of 30 years. The example shows that for a medium voltage overhead transmission line in a 200 m span the sag after 30 years can increase up to 70 cm. The sag control of existing overhead lines is possible only when an adequate knowledge of the conductor temperatures is available. On disconnected lines, the air temperature at conductor height requires to be taken into account. The authors show possible ways of measuring the temperatures of conductors on live transmission lines.< >

Abstract: The Bolton Institute has carried out an extensive programme of testing masonry arch bridges, primarily to study the effect of soil structure interaction, spandrel wall and ring separation on their behaviour. The full programme has included both single and multi-span bridges. The paper describes three multi-span bridge tests and concludes that failure resulted from the development of a global mechanism at lower loads than those observed for similarly proportioned single span bridges. For the covering abstract of the conference see IRRD 858602.