Abstract: A precast, prestressed concrete joist having web openings through which mechanical and electrical equipment may pass. In an exemplary embodiment, the joist comprises generally horizontal opposite top and bottom concrete members with a concrete web interposed between them. This web may have openings through which mechanical and electrical equipment may pass. Prestress steel strands may extend lengthwise through both the top and bottom members to provide prestress in the concrete joist. The concrete joist may further comprise strand restraining devices for deflecting the prestress steel strands. The precast, prestressed concrete joist having a web opening may be constructed using a reusable casting apparatus. This casting apparatus comprises a prestressing bed onto which a frame may be mounted. The frame provides a means of applying tension to the prestress steel strands and of supporting prestress strand restraining devices.

Abstract: A method and assembly (20) to form a cast concrete panel (21). The assembly (20) has end beams between which tendons (23) can pass. The beams need to be able to support tensioning of the tendons. Transversely extending form members (25) cooperate with form members (27) to enclose a space to receive concrete to form the panel (21). The tendons (23) pass through the space.

Abstract: A post-tensioning apparatus and method including first and second body sections interconnected by an intermediate anchor head. Each body section has an end anchor head on an end opposite the intermediate anchor head and includes a tendon with a pair of strands adapted for being tensioned between the intermediate anchor head and the corresponding end anchor head of each body section. Each pair of strands is encapsulated between the intermediate anchor head and each corresponding end anchor head of each body section in a mechanically interlocked duct adapted to receive a bonding agent after tensioning of the strands. A passage is provided proximate the end anchor head of the first body section and provides a passage for insertion of bonding agent, preferably in the form of grout, into the duct of the first body section. Grout can be injected through the passage proximate the end anchor head of the first body section such that the grout can enter and fill the duct of the first body section.

Abstract: Methods and articles for reinforcing castable compositions through the use of reinforcing elements maintained in a close-packed alignment in a dispersible containment means.

Abstract: Parallel spaced grooves are cut within the surface of an existing reinforced concrete member in the direction of bending and at locations where existing tensile reinforcing is inadequate. Elongated reinforcing elements, such as composite rods with continuous carbon fibers, are positioned within the grooves, after a curable bonding material, such as an epoxy resin, is inserted into each groove so that the bonding material surrounds the reinforcing element. The material is formed flush with the surface and allowed to cure to bond each reinforcing element to the concrete defining the corresponding groove. The grooves and reinforcing elements extend within the top surface of a concrete slab across a beam or support for the slab, extend within the bottom surface of the slab at least fifty percent of the distance between adjacent supports for the slab, or within a vertical surface of a concrete or masonry wall or column.

Abstract: Methods and articles for reinforcing castable compositions through the use of reinforcing elements maintained in a close-packed alignment in a dispersible containment means.

Abstract: Method of producing concrete structures with a surface protection layer and a concrete layer. The method includes moulding the concrete layer and the surface protection layer using a "wet in wet" process. The surface protection layer preferably consists of a cement allied mortar having a low water binding average ratio and a binding agent strength above 70 Mpa. The concrete layer which preferably consists of a concrete having a lower binding agent strength than the surface protection layer, is preferably an air entrained ballast concrete with dense structure and a strength in the range of 10-20 Mpa. The surface protection layer is cast in the bottom of a mold, and the concrete layer is cast above the surface protection layer. During desiccation of the material, the surface protection layer shrinks less than the concrete layer, so that pressure strains are created through deformation differences in the surface protection layer and concrete layer.

Abstract: A road transportable concrete railroad long-line tie molding system is described in which a rigid horizontal metal stressing frame is assembled from transportable sub-frame segments. The sub-frame segments are releasably connected in axially aligned end-to-end relation, and include parallel longitudinal reaction members. In a preferred form, the sub-frame segments are convertible from inoperative transport conditions to extended operative conditions. Footings are provided along the stressing frame length to engage the sub-frame segments to releasably mount the sub-frame segments in axial alignment and stabilize the reaction members against lateral deflection during compressive loading. A plurality of conventional gang tie molds having upwardly open elongated mold cavities are releasably received in end-to-end alignment along the framework. A reinforcing wire anchor is provided on the sub-frame at the dead end of the framework and a tensioner is located at the live end of the framework.

Abstract: The manufacture of moldable concrete products with deferred mold release incorporates molding means bm1 into optimized rotary structures 1, 5, 7, 9, 12 in the form of modular cylinders having at least two faces, the cylinders being equipped and/or associated with means which group together the main work-stations MP, MT, B, D, NH so as to assign a rotary travel of more than 270.degree. and preferably equal to 360.degree. to the curing of the molded material with or without recourse to any means for accelerating the curing.

Abstract: A prestressed concrete tensioning system for a tensioning tendon in the construction of a prestressed concrete beam comprising an anchor seat and a prestressed tensioning device. The anchor seat embedded in one end of the beam and has spherical structure and inverse ratchet gripping device therein for adjustably holding one end of the tendon. The tensioning device has a hollow cylindrical housing including a hydraulic fluid chamber therein for slidably disposing a piston member in associated with a wedged surface grip means which are operated by hydraulic pressure for gripping and tensioning one end of the tendon, and a hemisphere concave in the forward end of the housing for engaging with the hemisphere convex of the anchor seat to obtain an universal joint effect. This disclosure is characterized in the prevention of shear and strength declination to the tendon and the risk to the ambient personnel.

Abstract: A connection method for connecting precast concrete beams involves supporting both ends of the precast concrete beams, lifting up the central points of the precast concrete beams, placing concrete in the gaps between the ends of the precast concrete beams, and positioning tendons through anchor blocks which project from the precast concrete beams. The tendons are then tensioned and, substantially simultaneously, the lifting forces applied to the concrete beams are reduced. The connection method reduces the bending moment caused by the self-weight of precast concrete beams and, as a result, reduces the size of the beam section.

Abstract: Pre-stressed concrete railroad ties are manufactured by the slip form process in the absence of mold members, other than the slip form itself. Tie casting occurs on portable casting soffits between portable soffit anchored deadmen supporting the pre-stressed tie tensile members immediately overlying the casting soffit. Tie formation occurs with the slip form passing around and over the pre-stressed tension members. Track fastening hardware is vibrationally inserted through windows of the slip form to place the track fastening hardware to precise measured dimension along the route of slip form movement and to configure that portion of the tie adjacent the track fastening hardware. End of tie locations as well as tie batch identification are likewise marked during the slip form process. Upon cure, the ties are cut at their marked end location.

Abstract: A filled hollow structure, such as a fence post, which is constructed with a hollow member filled with a core to increase its strength. One aspect of the structure is that the core material normal expands upon setting, so that, when hardening within the hollow member, the expansion is restrained by the hollow member and the core is formed into an integral structure with the hollow member. Further strength is added by constructing the hollow member of reinforced fiberglass with the fiberglass rovings oriented at an angle to the axis of the pipe and by using a hard coating on the outside of the pipe.

Abstract: A method for the grouting of an unbonded post-tensioned cable in a concrete structure which cable is enclosed in a cable sheath is disclosed. The method includes the steps of pumping a curable hydrophobic grouting material, for example a polyurethane resin into the cable sheath to fill a selected length of the cable sheath with the grouting material and continuing the injection until the selected length of the sheath is filled with the grouting material and the material expelled from the sheath no longer includes any admixed water. Infiltrated water in the cable sheath is expelled by way of the injected grouting material so that corrosion of the cable is stopped and further corrosion prevented. The grouting material also bonds to the cable and the sheath thereby preventing a sudden eruption of the cable from the surrounding building structure should the cable break.

Abstract: A novel method for fabricating pretensioned concrete structures includes the steps of:(a) arranging one or more cables between a first anchoring station and a second anchoring station;(b) tensioning the cables between the anchoring stations at a selected tension load and in a selected cable position;(c) casting one or more concrete structures around the cables at a selected location between said anchoring stations; and(d) repeating steps (b) and (c) using different tension load and/or cable position selections in step (b).

Abstract: For a stressing anchorage for a tension element running inside an encasing tube, a bearing plate with an annular opening is set up on an outer wall of a structural part. In an area of the opening turned away from the structural part there is a cone opening outward. A trumpet of plastic is bonded to the encasing tube, likewise of plastic, at its end situated in the structural part. The outer end of the trumpet is more or less flush with the face of the bearing plate turned away from the structural part. A transition piece projects into the trumpet with a projection leading in whose surface area is shaped frustoconically. Owing to the truncated cone, the outer end of the trumpet is pressed against the cone of the bearing plate, and is held firmly in an annular gap between the said truncated cone and the said cone after the anchor head is placed on the transition piece and the tensioning strands of the individual tension elements are pre-stressed and are held with the wedges.

Abstract: A method for the manufacture of pretensioned prestressed concrete sleepers wherein, the tensioning wires are taken directly from one or more rolls of wire and are introduced in a longitudinal feed into a tensioning frame, and the tensioning wires (5) are initially anchored at the end thereof located at the front in feed direction. The wires are tensioned by a tensioning device arranged outside of the tensioning frame and resting against the opposite end thereof, and the wires (5) are anchored at the tensioning device; only then are the wires severed by means of a severing device. In this manner, it is possible to combine in a single station the operating stages of cutting to length, introducing and tensioning the wires, which stages in the past were distributed over several manufacturing stations, so that the labor intensive and time consuming manipulation of wires which have been previously cut to length is eliminated.

Abstract: A pocket former having a body with a tapered exterior surface. The body has a top surface and a bottom surface and a tubular member extending therethrough. The top surface extends outwardly from the tubular member for a greater distance than the bottom surface. The top surface and the bottom surface define a pocket therebetween. The top surface tapers to the bottom surface. The pocket has a generally semi-circular configuration at one end with a top surface forming a linear edge of the semi-circular configuration. The pocket has another portion of generally circular configuration. A plurality of radial struts extend from the tubular member to the top and bottom surfaces.

Abstract: A method for introducing a prestress into a concrete member includes the steps of passing a steel rod (2) through a hollow steel rod (1), applying a tensile force to the hollow steel rod (1), while using the steel rod (2) as a reaction support member, placing concrete (4) around the hollow prestressed steel rod (1), and hardening the concrete (4). The apparatus includes a flat bearing support plate that abuts the concrete to be prestressed, a jack and ram, a rigid support member for interconnecting the jack and ram to the bearing support plate, and a holding cylinder positioned between the bearing support plate and the jack and ram. The bearing support plate and a leading end of the holding cylinder are apertured and screw threadedly receive the threaded trailing end of a hollow steel rod. The trailing end of the steel rod is screw threadedly received by the trailing end of the holding cylinder.

Abstract: A prestressed, reinforced concrete structure is made by applying a coating onto a reinforcing element, introducing the coated reinforcing element into the body of concrete, and heating the reinforcing element so that first the coating melts and a bond between the reinforcing element and the body of concrete is interrupted and the reinforcing element is expanded and thereafter heating the reinforcing element to a higher temperature at which the coating rigidifies and provides a firm bond between the expanded reinforcing element and the body of concrete.

Abstract: A method for preparing a carbon fiber-reinforced cement material is here disclosed which comprises the step of using, as a reinforcing material, a carbon fiber from which a gas has been removed by replacing the gas captured in the fiber with water. This method permits providing the carbon fiber-reinforced cement material having a large reinforcing effect by the fiber.

Abstract: A long span truss of substantially conventional steel construction provided with concrete encasement of the top and bottom chords with the concrete encasement being reinforced and the concrete encasement on the bottom chord and optionally on the top cord including post-tensioned steel tendons. The invention further relates to a method of making the truss as described above in which the light structural steel truss is first erected and provided with temporary steel scaffolding and bracing to support formwork. Reinforcing steel and steel tendons are placed in the formwork and concrete is poured to encase the top and bottom chords of the truss. The steel tendons are post-tensioned to provide maximum load support capability.

Abstract: A switch cross tie is made in a mold having a base plate formed with a plurality of holes in a predetermined pattern corresponding to a particular type of concrete switch cross tie by first overlying the entire base plate of a mold with a covering sheet provided with markings in a pattern corresponding to that of the holes needed for another particular type of concrete cross ties. This covering sheet overlies and blocks all the holes formed in the base plate and it is fixed in place atop the base plate. Then the operator or a computer-guided drill press cuts through the covering sheet and into the base plate at each of the markings to form thereat a respective new hole. Each such new hole is fitted with an anchor, and the mold is filled with concrete over and around the anchors with the covering sheet blocking all the holes other than the new holes. It is important that the covering sheet be sufficiently strong to inhibit entry of concrete through it into any of the holes other than the new holes.

Abstract: A method of post-tensioning a truss of substantially conventional steel construction provided with concrete encasement or cladding of certain chords while the truss is in a fabrication yard or at ground level before erection and installation in which the structural steel truss is first assembled in a fabrication yard with certain of the chords being provided with formwork. Reinforcing steel and steel tendons are placed in the formwork and concrete is poured to encase the chords of the truss while the truss is positioned horizontally or vertically in the fabrication yard or at ground level. The steel tendons are then partially or fully post-tensioned to provide maximum load support capability. The cladded and partially or fully post-tensioned truss is then lifted to an installation point and a load deck placed on the truss with final post tensioning of the truss then being completed.

Abstract: A switch cross tie is made in a mold having a base plate formed with a plurality of holes in a predetermined pattern corresponding to a particular type of concrete switch cross tie by first overlying the entire base plate of a mold with a covering sheet provided with markings in a pattern corresponding to that of the holes needed for another particular type of concrete cross ties. This covering sheet overlies and blocks all the holes formed in the base plate and it is fixed in place atop the base plate. Then the operator or a computer-guided drill press cuts through the covering sheet and into the base plate at each of the markings to form thereat a respective new hole. Each such new hole is fitted with an anchor, and the mold is filled with concrete over and around the anchors with the covering sheet blocking all the holes other than the new holes. It is important that the covering sheet be sufficiently strong to inhibit entry of concrete through it into any of the holes other than the new holes.

Abstract: A prestressed concrete beam is made by first fitting the opposite ends of a group of reinforcing rods through respective holes in a pair of longitudinally spaced end plates having longitudinally confronting inner faces and opposite outer faces, then providing on each of the rods a head bearing longitudinally inward on the respective outer face, and then applying opposite outward traction to the end plates to tension the rods and filling around the rods and between the inner faces of the plates with a mass of concrete. The concrete mass is then cured and the traction on the end plates is released. Subsequently the heads of the rods are released from the plates and the plates are removed from the ends of the mass of cured concrete. The heads can be machined or burnt off, or the plate can be constructed to release them.

Abstract: A steel reinforced cement product having substantially increased strength made by: positioning prestressed reinforcing steel in a mold cavity; providing a cementitious mixture in the mold cavity about the reinforcing steel in an amount sufficient to fill the mold cavity to a predetermined extent; curing the reinforced cementitious-steel composite article in the mold; drying the article; applying a glaze to the surface of the dried article; burning the glaze; cooling the burned, glazed article, whereby reducing the strength of the composite article; hydrating the reduced strength composite article; and then recurring the thus produced article.

Abstract: A thin-walled ferrocement product is formed from mortar supplied in a liquid or semi-liquid state, and a thin foraminous layer of reinforcement positioned centrally between the opposite wall surfaces of the product. The liquid or semi-liquid mortar is deposited in a uniform layer on a conveyor and the reinforcing material is positioned parallel to the lower surface of the conveyor. In a preferred embodiment, the material is maintained under tension at the desired position above the conveyor surface as the mortar is deposited onto the conveyor and flows through the foraminous reinforcing layer. The mortar is developed to a coherent plastic state before removal from the conveyor, preferably with the application of heat. The developed plastic material may be formed into various configurations, or may be maintained flat, while subjected to curing to a solid state. The developed plastic ferrocement material may be separated into convenient lengths for handling.

Abstract: There is provided an apparatus for producing a paving block comprising a block substrate and a solid top layer selected from a tile-like layer and a cured cement mortar layer firmly bonded onto the upper surface of the block substrate. The apparatus comprises a mortar applicator (21) consisting essentially of a mortar container and a masking bottom board (23) having an opening (24) to be located on the back of a top layer (1-2) or the upper surface of a block substrate (1-1) during application of cement mortar thereon, a clamping plate (25) to be located on the top layer (1-2) placed on the block substrate (1-1) during bonding them, and a scraping frame (26) for scraping excess mortar remaining on the side surfaces of the bonded block. When the apparatus is used to produce a novel paving block comprising a block substrate and a solid top layer having a plane dimension smaller than the substrate, squeeze-out deposits (6) of the cement mortar (7) are further formed around the bonded top layer (1-2).

Abstract: In casings for switch cross ties, the bottom plate 3 serves at the same time as a pattern for the position of the construction components. As a rule, a new casing is prepared for each series of cross-ties type. In small series with various positions of the construction components it is economical to use the bottom plate repeatedly. This is done by providing the bottom plate, prior to its insertion in the casing, with holes (A,B,C) for several types of finished parts, by provisionally closing the unnecessary holes by suitable means and by finding the combination of holes required for the production of a certain type of finished part through a certain searching procedure and freeing them of their provisional closing means.

Abstract: Methods of forming cast prestressed concrete elements and structures include a non-corrosive reinforcing element being formed of a plurality of substantially parallel continuous filaments embedded in a matrix of thermosetting resin. These reinforcing elements are tensioned, then concrete cast about the elements is permitted to harden and the tension transferred to the now-hardened concrete in order to prestress the same. The resulting concrete elements and structures have high resistance to alkali induced corrosion of the prestressing elements.

Abstract: A prestressing arrangement and technique for the manufacture of prestressed bodies or structures includes shape memory material members. According to one aspect of the invention, the prestressing arrangement includes a tensile member in series with a shape memory material member. The formable material is shaped around the members and fixed in form. The shape memory material is then shrunk by heating it above its characteristic threshold temperature, placing the members in tension and the fixed material in compression. According to another aspect, the shape memory material member is secured in a tube. Prestressing is achieved in the tubular prestressing arrangement by lengthwise expansion of the shape memory material member prior to fixing the material of the body being formed, and then after fixation, releasing the stress on the shape memory material member, leaving the tube in tension to exert compressive forces on the fixed material.

Abstract: A prestressed concrete article including overlying the ends of the article and having gasket rings between the article and the end walls. A hardenable medium is injected between the jacket and the concrete article and generates a sufficient pressure so as to outwardly bulge the jacket, drawing the end walls together thereby compressing the gaskets.

Abstract: The intermediate anchor includes an abutment body for an end of an anchoring element mounted on an end of a pretensioning element, the abutment body is supportable on an inner side of a wall of the centrifugal concrete mold and mountable on the inner wall. At least one anchor bolt extendable through the wall of the centrifugal concrete mold in a sealed manner mounts the abutment body. The abutment body has a conical recess extending transversely to the anchor bolt for receiving the anchoring element of the pretensioning element. A wedge-shaped projecting piece is releasably mounted on the abutment body and engages the tensioning element in a fork-shaped manner near the anchoring element. The projecting piece is releasable after removal of the pretensioned concrete body from the centrifugal concrete mold and before removal of the abutment body from the concrete body so as to release a portion of the pretensioning element near the anchoring element for separating by a separating device.

Abstract: In a concrete column supporting an overhead load and having a base end resting on a surface, a process of strengthening the column to increase its ability to withstand atypical physical loading accompanying an earthquake, involving the steps of defining a work area about the surface of the column to which the strengthening is to be applied, the work area defined by circumferential marginal edges arranged in spaced-apart relation; overwrapping the work area with at least one layer of high-strength, stretchable fibers wherein the fibers are oriented at an angle to the vertical axis of the column; applying a coat of hardenable material, having a modulus at least as great as that of the fibers, over the layer of fibers to form a hard outer shell thereover; and, injecting a quantity of a hardenable, low-shrink liquid under the layer of fibers and over the surface of the work area in an amount sufficient to cause the fibers to undergo stretching from about 1/2% to about 4% of their elongation.

Abstract: The invention concerns a prestressed construction element of composite structure comprising a bar- or tendon-like inner part (1) of high tensile strength, a sheat part (2) of, e.g., high-strength concrete or ceramic material, adapted about and precompressed by the inner part (1), and a shape-forming structure (4) adapted about the sheath part (2) with dimensions corresponding to the desired dimensions of the construction element. According to the invention, the structure (4) is such an elastic material as is capable of taking both compression and tensile stresses without cracking. The construction in accordance with the invention achieves a strong and easily workable construction element.

Abstract: The fracture-free paving block (1) comprises a cement block substrate (1-1) and a top solid layer (1-2), and is characterized in that the top layer is selected from a cured cement mortar layer and a tile-like layer firmly bonded to the substrate with cement mortar; the top layer is bonded to the block substrate with lateral margins (2) of 1 to 8 mm wide in horizontal distance (1.sub.5) from the peripheral edges of the substrate: and the vertical distance (1.sub.6) from the surface of the top layer to the peripheral edge of the substrate is 5 to 50 mm. The method for producing the paving block (1) having a tile-like top layer comprises applying adhesive cement mortar between the back of the top layer (1-2) and the upper surface of the substrate (1-1); placing the top layer on the substrate with the above-mentioned margins (2) of the substrate surface: and applying vibration and/or pressurization between the top layer and the substrate.

Abstract: A method of manufacturing a three-sided culvert includes prestressing tendons in the culvert form. A series of prestressing tendons are secured within a form adapted for casting a concrete culvert having three orthogonal sides. The prestressing tendons are utilized in the top slab of the three-sided culvert and are positioned within the form prior to the pouring of concrete therein. Reinforcing steel can be eliminated along with the costs associated therewith and a culvert configuration can be provided with enhanced strength and improved material properties. Such culverts may thus be provided in modular form for placement upon foundations at remote locations for the creation of bridges, drainage areas and the like.

Abstract: A plant to manufacture elongated concrete elements, particularly railway sleepers of prestressed reinforced concrete. In the plant according to the invention, the forms for the production of said elements are supported on carriages sliding along parallel side-by-side tracks, and the operating machines designed to perform in succession a series of operations on said forms are positioned into a limited working area, housed inside a shed, and are mounted above said tracks, substantially fixed in respect of the longitudinal axis of the tracks but movable transversely thereto. The curing area for the concrete elements is arranged externally to the working area. In the case of prestressed reinforced concrete elements, the tensioning device for the reinforcement strands are mounted directly on each of said slidable carriages supporting the forms.

Abstract: A method for making a prestressed concrete article including a cylindrical body surrounded by a cylindrical jacket by joining end walls to the jacket overlying the ends of the article and placing gasket rings between the article and the end walls. A hardenable medium is injected between the jacket and the concrete article and generates a sufficient pressure so as to outwardly bulge the jacket, drawing the end walls together thereby compressing the gaskets.

Abstract: The present invention relates to shearing machine in which the upper shearing blade can be easily adjusted and positioned. The upper blade is held on a pivotal plate member which is pivotally held on a ram by means of a hinge to be rotated to adjust of the position of the upper blades. In addition, a hold down member is provided for holding a work-sheet. The hold down member is arranged to be urged by a toggle joint to hold the work-sheet at a reduced speed with an increased force after coming into contact with the work-sheet. A scrap removal member is also included in the shearing machine such that scraps can be easily removed without mingling them with the finished sheets. The scrap removal member removes scrap without idle time between feeding the work-sheets to be sheared. The shearing machine is so arranged that scraps are taken away directly to a scrap box as soon as the work-sheet has been complete sheared into its finished product.

Abstract: An apparatus for setting up a concrete form for the subsequent forming of a concrete member therein. The apparatus for setting up the concrete form includes a deck brush for cleaning the deck portions of an elongated concrete form, stem brushes for cleaning the stem portions of the concrete form, nozzles for spraying pressurized lubrication fluid onto the form, strand pulling and placing devices for placing reinforcing strands in the stem portions of the concrete form, rams for depressing the strands down into the stem portions after tensioning thereof, and a deck reinforcing material dispensing system which simultaneously straightens and dispenses deck wire onto the deck portion of the concrete form.

Abstract: In the formation of finished slide surfaces for slide rails on a track for an electromagnetically levitated vehicle, the track is constructed as a girder-like beam with the slide rails located on cantilevered parts of the upper surface of the beam. The beam can be formed of prestressed concrete. Initially the slide rails are provided with a height oversize. The height oversize part of the slide rails is removed and the slide surface of the rails are finished to the desired degree. The height oversize part is removed by cutting and grinding devices mounted on a machine frame movable over the upper surface of the track. The machine frame is adjustable in the vertical direction from a datum plane formed by the lower surfaces of support stators secured to the undersides of the cantilevered parts of the track. The machine frame rides on the upper surface of the beam and is in contact with the lower surfaces of the support stators.

Abstract: In pulling or pushing steel tendons, such as strands of steel wire through ducts positioned in a concrete structural member, the ducts are sheathing tubes encased in the concrete of the structural member. To limit the friction acting on the tendon as it is displaced through a duct, forces acting in the axial direction of the duct or vibrations acting transversely of the axial direction of the duct are applied directly to the tendon. These forces are applied at recesses in the structural member accessible at its outside surface. The friction acting on the tendon is compensated by the axially directed forces and the application of vibrations greatly reduces the coefficient of friction. These forces acting on the tendon can be combined and are particularly useful for moving tendons around small radius curves and through large redirecting angles.

Abstract: An elongated prestressing steel material for use in the fabrication of prestressed concrete comprises a steel member and an outer coat of many microcapsules each containing a flowable material in its interior.

Abstract: Disclosed is a prestressed tube and a method of its manufacture. The tube includes inner and outer walls with an intermediate nonadhering lamina layer. A pressure medium is fluidically injected through one of the walls to the interface between the nonadhering lamina layer and at least one of the walls so as to form a cavity therebetween for receiving the pressure medium. The medium is thereafter hardened to provide a prestress force to the tube. The method includes the step of fluidically injecting pressure medium between the walls to the intermediate lamina layer and the interface between that layer and at least one of the walls, so as to form a gap therebetween for receiving the pressure medium. During the step, one or both of the walls may be expanded so as to form an enlarged cavity for receiving the pressure medium. The method thereafter includes the step of hardening the pressure medium so as to provide a permanent leak-proof prestress force to the tube.

Abstract: An anchor apparatus which provides corrosion protection for the exposed cable in a region around where the anchor body attaches to a tendon of a prestressed concrete slab is disclosed. A conduit is fastened to the inlet end of the anchor body. The other end of the conduit is taped or connected with heat shrink tubing to the covering of the tendon. The outlet end of the anchor body is closed either with a plug at an end anchor or with a second conduit and tape or heat shrink tubing at an intermediate anchor. Fittings are provided for inserting corrosion resistant grease into interior cavities as a second line of corrosion protection.

Abstract: Method for manufacturing glazed cement products of a foam light-weight aggregate, reinforcing steel under pretension or a stress-absorbing layer around the reinforcing steel. An action of generating crack, caused by a difference of coefficient of thermal expansion between the reinforcing steel and a portion of cement material while burning and cooling are carried out, is absorbed by the foam light-weight aggregate, the stress-absorbing layer or pretension given to the reinforcing steel. A reaction of unreacted cement component is promoted by the hydration to harden for recovering mechanical strength.

Abstract: A concrete filled steel tube column which includes: a steel tube connected to beams of a structure so that an axial compressive load is transferred from the beams to the steel tube; and a concrete core, disposed within the steel tube, for bearing an axial compressive load transferred from the beams via the steel tube to the concrete core. The steel tube has a plurality of prestressed tube pieces concentrically joined in series. Each of these tube pieces has an axial prestress introduced into it to counteract a stress resulting from the compressive load applied to the steel tube. With this arrangement, substantially no axial stress is induced in the steel tube. In constructing the column, a steel tube piece is erected, and beams are joined to the tube piece. An axial tensile load is applied to the tube piece so that an axial stress is induced in the tube piece. After the application of the load, concrete is charged into the tube piece.

Abstract: Methods for forming prestressed concrete members wherein a pressure-containing casing is disposed around the outside surface of the concrete member and is spaced therefrom so that a cavity is formed between the casing and the outside surface of the concrete member. A pressurized medium is injected into the cavity between the casing and concrete member at a pressure sufficient to apply the required prestressed compressive force to the outside surface of the concrete member. The pressurized medium changes form by hardening or solidifying after injection. Examples of solid pressurized mediums include cement-like grouts and plastic, and epoxy resin materials. When the concrete member is cast within the casing so as to be in intimate contact with the casing the cavity is then formed by peeling the concrete member and casing away from each other as the pressurized medium is injected therebetween.