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Systems and Concepts for Repair and Strengthening
DYWIDAG-SYSTEMS INTERNATIONAL
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DSI can assist you at any or all stages of a repair/strengthening project:
- inspection and condition evaluation of structures - preparation/review of the repair/strengthening scheme- design and dimensioning of the strengthening work- supply and installation of high quality DYWIDAG products- execution of the strengthening works- site supervision with quality assurance- monitoring and inspection controls.
Systems and Conceptsfor Repair and Streng-thening of Bridges andother Structures
Concrete is a durable and relati-vely maintenance-free construc-tion material. Nevertheless,repair and/or strengthening ofexisting structures may becomenecessary due to
- natural aging, inadequatedesign, poor quality of ma-terials, faulty constructionpractices
- severe environmental andaccidental influences (e.g.overloads, vehicular impacts,strong earthquakes, hurri-canes, fire)
- changes in use (e.g. load enhancement beyond the original design values)
- increased safety require-ments.
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DSI and DYWIDAG have more than thirty years of experience in the fieldof repair and strengthening works. Alongside traditional methods and systems, special repair and streng-thening techniques have been developed and applied with success.
For your repair or strengthening project you can use the following wellproven DYWIDAG systems:
vacuum grouting
cathodic protection
short bar tendons, strandtendons
external bar and strand tendons, ground anchors
bar tendons, GEWI® bars
GEWI® bars, bar tendons,stay cables
bar and strand tendons
bar tendons, GEWI® piles
rock anchors
ground anchors, GEWI® piles
lifting system using prestressing bars
restoring corrosion protec-tion of prestressing steel
restoring corrosion protectionof ordinary reinforcement
improving interaction betweenold and new concrete
strengthening of bridges
strengthening of historic buildings
modification/expansion ofexisting structures
seismic retrofitting of bridges
seismic retrofitting of buildings
stabilizing of dams
seismic retrofitting of foundations
lifting/moving of structures
Autopista del Sol, Cable Stayed Bridges, MexicoFour cable stayed bridges between Cuernavaca and Acapulco were inspected. First a detailed inspection program with a numerical and qualitative rating system was developed. A detailed report on the quality and state of the main parts ofeach bridge, especially superstructures, pylons and stay cables aswell as recommendations on remedial measures were proposed to the owner.
Inspection and conditionevaluation of structures
The efficiency of any repair orstrengthening scheme dependsvery much on an accurateassessment of the actual stateof the structure. Testing and ins-pection methodology should bebased on an incremental stra-tegy: the type and extent of fur-ther testing are decided as defi-ciencies are uncovered.Although non-destructive testingmethods are usually preferred,they should be complementedby destructive methods as nee-ded to obtain a clear understan-ding of the nature, causes andextent of the defects.
Point Beach Nuclear PowerPlant, Two Rivers,Wisconsin, USAInspection of the post-tension-ing tendons of two containmentstructures was carried outaccording to the safety specifi-cations of the US NuclearRegulatory Commission. Bothvisual and physical inspection(lift-off, detensioning and tensiletests) were carried out on selec-ted tendons from all tendongroups (hoop, vertical and dometendons).
+ + + + DSI Services + + + +Elaboration of inspectionprogram and evaluationsystem, inspection, detailedreport on quality and state of the relevant parts
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+ + + + DSI Services + + + +inspection, testing, detailedreport
Restoration ofCorrosion Protection
One of the most important tasksof civil engineers to ensure thedurability of structures is the cor-rosion protection of steel ele-ments.DSI offers efficient and advancedmethods for restoring corrosionprotection of both, prestressingand reinforcing steel.
+ + + + DSI Services + + + +consultancy during assess-ment of the actual state of the piers, elaboration ofrepair programme, dimen-sioning of the CP system,supply and installation ofthe CP system.
cathodic protection
Restoring corrosion protec-tion of reinforcing steel
Besides the traditional corrosionprotection methods in which thecarbonised or the chloride-con-taminated concrete is mechani-cally removed and replaced withnew alkaline concrete, DSI hasemployed a highly reliable elec-trochemical corrosion protec-tion method: cathodic protection (CP).
A low intensity direct current (5-20 mA/m2) is continuouslyapplied between the reinforce-ment (the cathode) and a dur-able anode (made for exampleof titanium) which is embeddedinto a cementitious overlay onthe old concrete surface. Theefficiency of the CP measure iscontrolled through potentialmeasurements on the embed-ded reference cells. This protec-tion measure is more econo-mical than traditional methods,as only the mechanically dama-ged concrete must be removedwhereas the chloride contami-nated concrete may be left undisturbed.
Bridges on the Brenner Highway, AustriaMany ducts in prestressed bridges of the Brenner Highway were checked for quality of grouting. The detected voidswere vacuum grouted.
vacuum grouting
Restoring corrosion protec-tion of prestressing steel
Where ducts are not complete-ly filled with cement grout, sub-sequent grouting must be car-ried out. This can be accom-plished by vacuum grouting. The advantage of this procedu-re is that regrouting of the ductrequires only one drilled hole for each void.
Special devices and tech-niques have been developedby DSI for careful drilling ofducts to avoid damaging theprestressing steel. The volumeof the void is measured bycreating a vacuum, which alsosucks the grout into the void. A comparison between themeasured volume of void andthe amount of grout consumedprovides a control measure onthe success of the operation.
Outer Noesslach Bridge, Brenner Highway, AustriaThe concrete of the 50 m high piers at the buttresses of the 180 mlong arches was highly chloride contaminated up to a depth of60 mm due to twenty years of exposure to de-icing salts. CP wasapplied to 1,500 m2 of the concrete surface, as only this measure did not jeopardize the load-bearing capacity and stability of the bridge. Efficiency and performance of the CP system can be mo-nitored at any time through potential measurements.
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In 1994 cracks were discoveredin the concrete corbelled piercaps of the Muza line steel gir-der viaduct. The emergencyrepair scheme consisted of placing external ø 36 mmDYWIDAG bar tendons(THREADBAR®) on both sides of the pier cap. These wereanchored in steel grillages ateach end of the caps and were supplied with DYWIDAGdouble corrosion protectionsystem. All exposed steel partsof the grillages were protectedby a three coat paint system.On selected tendons permanentload cells were installed to mo-nitor the prestressing forces.
MRT rapid transportationnetwork, Muza Line, Taipei,Taiwan
+ + + + DSI Services + + + +preparation of the rehabili-tation scheme, supply ofsteel grillages and DYWIDAGbar tendons, execution ofthe strengthening works.
One of the main problemsencountered in strengthening is how to achieve compatibilityand interaction between theexisting structure and thestrengthening elements.
The force transfer across thejoint between old and newconcrete can be accomplishedin different ways:
- simple friction between sur-faces of the existing concreteand the prefabricated concretemember (dry joint)
- simple bond between the existing concrete surface andthe concrete of the new partcast on site (wet joint)
- the efficiency of both jointscan be considerably im-proved through increasing the force normal to the joint.
Interaction between the original and the new concrete parts
This may be easily achievedby post-tensioning. For thispurpose DYWIDAG tendonscan be employed. In the case of very short tendons, the fine thread at the end of thesmooth bar results in ananchorage with an extremelysmall slip. In the case of shorttendons, where bond is re-quired, bar tendons usingDYWIDAG bars (THREADBAR®)may be used. For longer andcurved tendons, strands offer a solution.
Strengthening ofStructural Members
Strengthening of structuralmembers can be achieved by
- replacing defective, or poorquality material
- attaching additional load-bearing material (for example:reinforcement, high qualityconcrete, thin metallic or non-metallic straps, post-tensioningtendons, or various combina-tions of these methods)
- redistributing action effectsthrough imposed deformationof the structural system.
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Opened in 1878, this landmark in the northern Portuguese costaltown of Viana do Castelo was designed and built by A.G. Eiffel.Strengthening of this ten span, 562 m long steel bridge with twomain truss beams of 7,5 m depth became necessary to adapt the load-bearing capacity to modern road and railroad traffic.However, the characteristic architecture should not be impairedthrough the construction measures. The consultant decided toinstall tension ties in every span. These run parallel to the bottomchords and are lifted up diagonally to the top chords above thepiers. The forces are introduced into the structure with ø 32 mmDYWIDAG smooth bars. Deflection points and coupling splices of the bars were installed very simply and economically.
Rio Lima Bridge, Viana do Castelo, Portugal
+ + + + DSI Services + + + +study of the causes of thedefects, preparation of the rehabilitation scheme, dimen-sioning of the strengtheningsystem, supply and installa-tion of the system, final con-trol, acceptance test.
+ + + + DSI Services + + + +supply of DYWIDAG bars,accessories and corrosion protection.
Won Hyo Bridge, Seoul,South Korea
The 1,120 m long bridge overthe Han River was completed in1981. Because of inaccuratecalculations of prestressing los-ses and deflections caused bycreep and shrinkage of concrete,additional deflections of up to30 cm occured. These resultedin 5 cm to 20 cm sagging at thehinges. The DSI rehabilitationconcept called for external ten-dons, which on the one handslightly reduced deflections andon the other strengthened thestructure. The remaining sagcould be eliminated by an addi-tional asphalt layer. Twelve 19 x 0.6" DYWIDAG tendonswere applied in each cantileverand anchored in new concretebuttresses cast inside the boxgirders. These were connectedto the concrete of the existingwebs of the box girder throughfriction created by the means ofshort ø 36 mm DYWIDAGsmooth bar tendons.
external bar and strand tendons
Strengthening of bridges
Bridges of any material can bestrengthened by adding externalpost-tensioning tendons. The influence of post-tensioningon serviceability and ultimatelimit states can be varied withinwide limits by selecting differentmethods of introducing prestres-sing forces and using varioustendon profiles.
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Burlington Skyway, Ontario, Canada
This 2,560 m long steel bridge built in the mid 50’s was repaired andstrengthened in order to increase the number of lanes from four tofive and to support the heavier design loads of the current codes.
The three main spans (84-151-84 m) consist of a continuous trussarch structure where the two longitudinal main trusses are connec-ted by bracing bents and transverse floor trusses. These trussessupport longitudinal deck stringers which in turn support a reinfor-ced concrete deck. The transverse floor trusses consist of standardstructural steel shapes riveted and bolted together. The increasedloading resulted in significant overstressing of the transverse floortruss members. These trusses were strengthened by external post-tensioning using ø 36 mm DYWIDAG bars (THREADBAR®) and a limited addition of new structural steel. This method allowed aminimal number of members to be dismantled and eliminated theneed for strict dimensional tolerances that would be required withthe addition or replacement of truss members. The selected dra-ped tendons were anchored in the deck slab to maximize theireffectiveness. A unique steel plate assembly was bolted to thetruss joint at the deviation point of the tendon to anchor the barsand transfer the tendon force to the truss. The bars were protectedby a three coat zinc/vinyl paint system.
Due to deterioration the entiresuperstructure of this steel-timber composite bridge wasto be rehabilitated. The 3 singlespans of 7-18-7 m consist ofstandard wide flange steelbeams at 1.2 m spacing.The existing transverse nail-lami-nated timber deck was replacedwith a longitudinally laminated,transversely prestressed timberdeck. The bridge was repairedin two stages to maintain onetraffic lane at all times. Transversely prestressed tim-ber decks are stiffer and more durable than nail-laminatedtimber decks. Prestressing in-hibits relative movements be-tween the timber laminates and greatly improves wheel load distribution.
Cripple Creek Bridge, Highway 101, Ontario, Canada
+ + + + DSI Services + + + +supply of DYWIDAG bars(THREADBAR®), specialanchorages and tensioningequipment, installation andstressing of the post-tensio-ning system.
+ + + + DSI Services + + + +supply of DYWIDAG bars(THREADBAR®) and tensio-ning equipment.
The transverse prestressingsystem consists of galvanized ø 26 mm DYWIDAG bars(THREADBAR®) placed at300 mm spacing. Tensioningwas repeated 1 week and 5weeks after the initial stressingoperation, to compensate forthe large creep losses in thetimber deck system. DYWIDAGbars (THREADBAR®) easilyallow the repeated retensioningboth at the time of construc-tion, and in the future if neces-sary. Connecting of the tendonsbetween the 1st and 2nd stageconstruction was accomplishedby using standard couplers.
Restoration ofCorrosion Protection
One of the most important tasksof civil engineers to ensure thedurability of structures is the cor-rosion protection of steel ele-ments.DSI offers efficient and advancedmethods for restoring corrosionprotection of both prestressingand reinforcing steel.
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Gänstor Bridge, Ulm,Germany
The frame legs of this two-hinged bridge were formed byvertical columns and inclinedprestressed ties. After 30 yearsof service, cracks in the super-structure occurred. Surveyingrevealed some ungrouted ductswith corrosion of prestressingsteel. Besides repair measures(vacuum grouting, injection ofcracks, restoration of concretesurface and water proofing)three strengthening optionswere considered:
- strengthening by means ofexternal tension ties in theform of permanent groundanchors
- strengthening with additionalreinforced concrete and pre-stressed concrete elements
- strengthening of the super-structure applying external tendons.
After analysis of costs and effi-ciency of each variant and theiraesthetic aspects, the variantwith permanent groundanchors was chosen.
The San Lorenzo Cathedralwas built between the 14 thand 15th centuries. Already in1633-1641 important consoli-dation works had been carriedout, since, because of theweight of the roof, the columnsand the walls had diverged.Seismic movements in 1983caused further damage, thusendangering the stability of themonument. A new consolidationand restoration project wasdecided after a thorough histo-rical survey of the original andsubsequent static behavior of the structure. The twenty-three timber roof trusses werereinforced by strengthening the joints with steel plates andbolts and by prestressing both
San Lorenzo Cathedral, Perugia, Italy
the lower tie beam and thecentral king post with two twinø 36 mm DYWIDAG bars(THREADBAR®) each. Thecolumn capitals showed dis-placements of up to 26 cm. A new system of transverseand longitudinal ties made of DYWIDAG bars (THREADBAR®)was introduced into the columnsand walls to prevent any sidedisplacements. The transversetie members were prestressedand tied back to the lateralwalls in order to apply to thewhole structure a system ofacting forces capable of counter-acting the thrusts of the vaults.
DYWIDAGBAR GROUND
ANCHOR
+ + + + DSI Services + + + +survey of damages, deter-mination of the actual load-bearing behavior, prepara-tion of the repair/streng-thening program, cost ana-lysis, supply of ø 26 mmDYWIDAG ground anchors,realization of the repair/strengthening measures,control at commissioning.
+ + + + DSI Services + + + +supply of DYWIDAG bars(THREADBAR®), rental of equipment, technicalassistance.
bar tendons
Strengthening of historicbuildings
Degradation of ancient buildingmaterials, prolonged exposureto environmental influences anduneven settlements makestrengthening of historic buil-dings unavoidable. Furthermore, it must be con-sidered that many historic buil-dings were built to a much lower degree of safety com-pared to similar modern struc-tures. Strengthening measuresmust be integrated into the building without altering its character and appearance.
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ground anchors
Strengthening of bridges
Columns, piers and tension tiescan be strengthened using ground anchors. In this case the ground anchorsact as external tendons to sup-ply additional uplift capacity orto increase the tie force betweendifferent parts of the structure.
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Santiago Bernabéu Soccer Stadium, Madrid, Spain
To increase the number of seats, the roof structure had to be raised.The existing reinforced concrete columns were strengthened andextended. They were lengthened by 12.5 m high steel columns with steel trusses cantilevering to 32 m and anchored by ø 40 mmGEWI® bars. Six GEWI® bars were anchored in each foundation,four on the tension side of the columns and two in the front. Thisarrangement carries the uplift forces from wind loads on the roofwhich was placed on top of the extended columns.
GrandhotelTaschenbergpalaisKempinski, Dresden,Germany
Built between 1707 and 1711,and completely destroyed by fire in 1945, this baroque palaceis now the site of a luxury hotel.During construction of a 4-sto-rey underground garage, theexisting south façade, with atotal weight of approx. 1,000 t,had to be supported 18 mabove the foundation level.GEWI® bars with various dia-meters were used as tension-ing and securing members. For the deep foundation of the western wing of the palace,GEWI® piles were drilled through the old cellar. The bond length of the piles is between 7 and 12 m.
16th Street Bridge over I-465, Indianapolis, USA
Two new merging lanes were tobe added to the highway underthe existing bridge. Since thebridge was only ten years oldand in excellent condition, it wasdecided to modify the structureby removing the end pier next tothe south-bound lanes and re-place it with a cable stayed sup-port system.For this complex modificationproject, a number of DYWIDAGsystems were used. The new2 m wide transfer girder wasprestressed with ø 32 mmDYWIDAG bar tendons(THREADBAR®).
Vertical prestressing of thedeadman pier shafts was exe-cuted with ø 36 mm DYWIDAGbar tendons (THREADBAR®)placed within a void to allow forlongitudinal movements. To anchor the footings of thedeadman piers against uplift for-ces of the stay cables ø 36 mmDCP DYWIDAG ground anchorswere used. The stay cablesconsisted of eight ø 36 mmDYWIDAG bars (THREADBAR®)inside individual steel pipes,which were cement groutedafter stressing.
DYWIDAGBAR TENDONS
DYWIDAGBAR GROUND ANCHORS
DYWIDAGBAR STAY CABLES
+ + + + DSI Services + + + +supply and installation of GEWI® bars.
+ + + + DSI Services + + + +conceptual design, proposalfor construction methodsand sequence, supply of bar tendons and bar staycables, field supervision.
GEWI® bars, bar tendons,bar stay cables
Modification / expansion ofexisting structures
New demands on the use ofstructures, such as new laneson the top or under a bridge oradditional seats in a stadium,may require modification of thestructural system or an exten-sion of its size. GEWI® bars and DYWIDAG bartendons with their excellentbond and fatigue strength properties are often used forthese works.
+ + + + DSI Services + + + +supply of GEWI® bars andpiles.
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Los Angeles County, Inter-section Freeway 10,57,210,California, USA
This very large superelevatedfreeway intersection requiredincreased bearing capacity ofthe substructure to satisfy trans-versal flexural seismic demands.New post-tensioned transversalpier cap beams were added oneach side and extended beyondthe ends of the existing struc-ture. Sixteen 15x0.6" tendonswith DYWIDAG multiplane an-chorages (MA) were installed.The upper tendons were con-ducted in pairs through holesdrilled into the webs of the exis-ting bridge girders. Large for-ces and confined space atsome of the pier cap beamsresulted in the first time use ofDYWIDAG 37x 0.62" strandtendons in California.
+ + + + DSI Services + + + +supply of DYWIDAG bars(THREADBAR®), hardwareand stressing equipment.
+ + + + DSI Services + + + +supply, installation, stressingand grouting of DYWIDAGmultistrand tendons.
bar tendons, strand tendons
Retrofitting of bridges
An essential seismic upgradingmeasure of bridges is to avoidthe loss of support for the bea-rings due to large relative displa-cements between the super-structure and the substructure. These measures should notimpede the free movement ofthe structure due to temperaturevariation or other effects. Oftenthe existing pier cap beamsmust be widened and strength-ened and the superstructuremust be restrained to the sup-port. Each of the following retro-fittings made use of post-ten-sioning tendons to increase thestability of the structure.
Elisian Viaduct, Los Angeles, California, USA
This bridge featured an old design concept of steel girders sup-ported by concrete pier cap beams. The new retrofit design specified extensive use of bar tendons throughout the entire struc-ture. The cap beam width was increased by adding new con-crete on both sides. Transverse ø 32 mm DYWIDAG bars(THREADBAR®) connected new concrete to old. Steel girder stability was increased by adding special spreader beams boltedto the existing webs at several locations. Spreader beams pla-ced in pairs were connected with an external restraint made of ø 32 mm bars (THREADBAR®).
Altamount Sidehill Viaduct,Northern California, USA
Thirteen pier cap beams of this440 m long bridge were retro-fitted with twin-tierod groupsconnecting each side of thesteel cap beam end to a newanchoring block. Tie rods, con-sisting of ø 36 mm DYWIDAGbars (THREADBAR®) placedinside of galvanized steel pipes,run inclined from the anchoringblock to a special steel „shoe“bracket fixed end. After a smallpost-tensioning force wasapplied at the anchorages, thetie rods were cement grouted.
+ + + + DSI Services + + + +supply of DYWIDAG bars(THREADBAR®) and hard-ware.
Seismic Upgrading
Structures have to withstandlarge horizontal and vertical ac-celerations and dynamic forcesduring earthquakes. This cre-ates special requirements on thestiffness and load-bearing capa-city of the structural members aswell as on their connections. Many existing structures mustbe improved to survive futureearthquakes. In California,following the Loma Prieta (1989)and Northridge (1994) earthqua-kes, approximately 1.300 con-crete and steel structures nee-ded seismic upgrading.
Cahuenga Boulevard Underpass, Los Angeles County,California
A new column was installed at the end of the pier cap beam tosupport an additional 3.6 m long concrete bolster, which increasedflexural capacity. Post-tensioned strand tendons placed in parallel,on each side of the pier cap beam, connected new concrete to theexisting box girders. A large steel bracket, attached to the bridgeweb at the tendon fixed end, allowed for uniform distribution of pre-stressing forces to the entire structure.
+ + + + DSI Services + + + +supply, installation, stres-sing and grouting of DYWIDAG multistrand tendons.
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Oakland City Hall, Oakland, California, USA
This historic landmark in the San Francisco Bay Area was built in1914. Since the Loma Prieta (1989) earthquake, the steel framebuilding with masonry infill has been completely rehabilitated. Due to the limited strength of the existing structure, the seismic isolationconcept was applied. At that time it was the tallest seismically isola-ted building of the world. Special base isolators were placed under each building column. The foundation thickness above the seismic isolators was increasedby adding new concrete around the perimeter of all footings. The interaction between old and new concrete was improved with ø 32 mm DYWIDAG transverse bar tendons (THREADBAR®) thatpassed through cored holes.
Designed with precast prestres-sed girders, the structure wasunder construction during theNorthridge earthquake. A similarly designed parkingstructure which collapsedduring this seismic event sho-wed a lack of reinforcement atshear walls. Design engineersdecided that short post-tensio-ned DYWIDAG bars (THREAD-BAR®), placed inside holes dril-led along existing shear walls,would compensate for reinfor-cing steel deficiency.
California State University, Long Beach Parking Structure,California, USA
Glendale Post Office, Glendale, California, USA
This historic masonry building,serving as post office, was com-pletely rehabilitated in 1995.New concrete shear walls wereadded to transmit forces duringa seismic event. These weresupported by ø 57 mm doublecorrosion protected (DCP)GEWI® piles which can be loa-ded with both tension and com-pression forces. During instal-lation, limited head room condi-tions required the contractor touse small bar sections of 3 mconnected with couplers.
+ + + + DSI Services + + + +supply of DYWIDAG bars(THREADBAR®), hardware and equipment.
+ + + + DSI Services + + + +supply, installation, stressingand grouting of DYWIDAGbars (THREADBAR®).
+ + + + DSI Services + + + +supply of GEWI® piles and stressing equipment.
bar tendons GEWI® piles
Retrofitting of buildings
Deficient structural systems or elements require streng-thening to withstand futureearthquakes. DYWIDAG bartendons, with their easy andreliable anchorage and cou-pling systems, can be appliedto upgrade these structures.
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rock anchors
Stabilizing of dams
Seismic performance of damsmay be economically improvedby adding rock anchors. A large number of dams havealready been stabilized usingDYWIDAG multistrand anchors.
The double curvature thin archconcrete structure was built inthe 1920’s and is approximately64 m high. Retrofitting becamenecessary to prevent a possiblefailure of the arch section, inwhich a separation along thejoints during a major seismicevent would occur. That was avery real danger as, during con-struction, the concrete coldjoints had not been properly cleaned of laitance, resulting in weak joints with little or nocohesion between pour sec-tions. The solution was to stabi-lize the dam by installing sixty-two 22 x 0.62" DYWIDAG rockanchors in the arch section to restore monolithic action. A further 22 anchors wereinstalled in the left thrust blockto provide for enhanced stabilityagainst sliding. As the anchorswere to be stressed and remainungrouted for a 100 days moni-toring period, protecting thestrands against corrosion
Stewart Mountain Dam, Arizona, USA
became an extremely impor-tant consideration. The super-ior corrosion protection andhigh bond capacity of the Flo-Bond epoxy coated strandprovided the ideal solution forboth requirements.
Railroad Canyon Dam, Canyon Lake, California, USA
The existing dam consisted of a thin 32 m high concrete archsection supported by concrete thrust blocks and concrete gravitywing walls. Earthquake specialists found that during MaximumCredible Earthquake water would probably overtop parapet walls,resulting in dam failure. For this reason each of the thrust blocksand wing walls were raised by adding new concrete. To increasestability, new and existing concrete was connected with anchors.The final design included six 27x0.6" and nine 48x0.6" DYWIDAGrock anchors with lengths up to 48 m. Flo-Fill /Flo-Bond epoxycoated strand was used for corrosion protection reasons. To allow for future load adjustment and long-term monitoring, spe-cial wedge plates with external thread and load cells were used.
+ + + + DSI Services + + + +consultancy during project,planning/quality mana-gement, supply, installationand testing of DYWIDAGrock anchors.
+ + + + DSI Services + + + +Supply of DYWIDAG rockanchors, uncoiling andstressing equipment.
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ground anchors,GEWI® piles
Retrofitting of foundations
In order to withstand theincreased loading on structuresduring a major seismic event,DYWIDAG ground anchors as well as GEWI® piles areused to enhance bearing ca-pacity and reduce foundationdeformations.
Steel water tanks, ContraCosta County, California,USA
During a seismic event, thetank contents will move fromside to side inducing dynamicuplifts on the tank foundations.To prevent damage at the foun-dation, high strength ø 25 mmand 32 mm DCP DYWIDAGbars (THREADBAR®) wereused as tie down ground an-chors around the steel tankperimeter.
Telecommunication tower, Diepenbeck, Belgium
The consultant decided to use DYWIDAG ø 32 mm bar tendonsfor rehabilitation of the existing anchors at the footing of the steeltower shaft. Since the foundation slab is supported by piles, theanchor plates for the lower anchorages could be mounted againstthe bottom side of the slab.
Los Angeles River Bridges,Long Beach, California, USA
To prevent damage to founda-tions during seismic events,column thickness and footingwidth were increased. ø 57 mmGEWI® piles were installed toenhance load-bearing capacity.
Britannia Secondary School,Vancouver, BritishColumbia, Canada
In order to meet modern re-quirements on earthquakesafety, this 70 year old buildingneeded to be retrofitted. Thedesigner chose high capacity ø 57 mm DCP GEWI® piles.Restricted by the low ceilingheight in the building, the 15 mdeep, ø 140 mm boreholeswere drilled with a track-moun-ted hydraulic minidrilling rig.The anchors were coupled insections from 2.7 m to 4 m.The tight restrictions of 2.7 mheadroom, 0.60 m spacing atthe pile head and pile inclina-tions of up to 40°, posed noproblem for this very flexibleinstallation method.
+ + + + DSI Services + + + +supply of DYWIDAG baranchors.
+ + + + DSI Services + + + +supply and installation of GEWI® piles.
+ + + + DSI Services + + + +supply, installation, stressingand grouting of DYWIDAGbar tendons.
+ + + + DSI Services + + + +supply of GEWI® piles andstressing equipment.
GEWIPILE
TANK WALL
DYWIDAGBAR GROUNDANCHOR
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Marsh Mills Viaduct,Plymouth, England
Because of severe damage tothe concrete from alkali-silicareactions, the entire structurehad to be replaced. The newstructure, a 410 m long, ninespan and 5,500 t heavy dualcarriageway road deck, wasjacked sideways 12.2 m intoposition using Ø 36 mm DYWI-DAG bars (THREADBAR®). Sliding was chosen as it mini-mized traffic disruption andwas significantly cheaper thantraditional methods. The newdeck initially carried traffic whileresting on temporary supports.After demolition of the old via-duct, eight new concrete piers
and two abutments were builtto support the new deck. Roadclosure was limited to a week-end – eight hours for the slide,24 hours to allow bearing groutto set and the remainder forasphalting and traffic re-routing.The merge slide was downhillon a 2.85 % slope. Balancebetween pushing and pullingforces gave a controlled pullingforce of up to 5,700 kN. Pullingwas incremental, governed bythe jack stroke of 600 mm,enabling a rate of travel of upto 1.8 m an hour.
bars (THREADBAR®)
Jacked sliding
Some rehabilitation schemesrequire the demolition andrebuilding of a portion of astructure. A very efficient method toachieve this is to move thestructure and then demolish itin its relocated position. Thiswill result in little interruption in the function of the remainingstructure and would allow anearly start of the reconstruction.Another effective rehabilitationtechnique is to construct thenew structure adjacent to theone to be demolished. Afterdemolition is complete the new structure may be shifted in a very short time to its finallocation.
Roof of a swimming hall, Marseille, France
Before a new roof of this swimming hall could be constructed,the old roof had to be removed. Traditional in-situ demolishingwould have incurred very high scaffolding costs and long roof-raising times. The DYWIDAG alternative to this method was to disconnect the roof from its supporting columns and move it in seven-meter long sections. Once the butt end of the building,had been cleared the roof was demolished. That proved to be by far the quickest and most cost-effective solution.
+ + + + DSI Services + + + +device development, supplyand installation of the liftingsystem, pushing.
+ + + + DSI Services + + + +supply of DYWIDAG bars(THREADBAR®).
Lifting/Moving ofStructures
Lifting and moving of structurescan be advantageously used aspart of a rehabilitation scheme:
- Lifting of structures as aneasy strengthening measure:redistribution of the action effects in a statically indeter-minate structure is achievedthrough imposed deforma-tions (e.g. through lifting a continuous bridge at its supports)
- Moving of structures or por-tions of them through jackedsliding.
DYWIDAG bars (THREADBAR®)with their easy anchorage ele-ments and mechanical couplingsystem are used as tension ele-ments for lifting or moving heavyand complex structures. If requi-red, DSI can assist you with thesupply of special equipment andtechnical support.
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www.dywidag-systems.com
AustriadywidAg-systemsinternAtionAl gmbhwagram 494061 pasching/linz, Austriaphone +43-7229-61 04 90Fax +43-7229-61 04 980 e-mail: [email protected]
dywidAg-systemsinternAtionAl gmbhteichweg 95400 hallein, Austriaphone +43-6245-87 23 0 Fax +43-6245-87 23 08 0e-mail: [email protected]
Belgium and LuxembourgdywidAg-systemsinternAtionAl n.v.industrieweg 253190 boortmeerbeek, belgiumphone +32-16-60 77 60Fax +32-16-60 77 66e-mail: [email protected]
Francedsi-ArtéonAvenue du bicentenairezi dagneux-bp 5005301122 montluel Cedex, Francephone +33-4-78 79 27 82Fax +33-4-78 79 01 56e-mail: [email protected]
GermanydywidAg-systemsinternAtionAl gmbhschuetzenstrasse 2014641 nauen, germanyphone +49 3321 44 18 32Fax +49 3321 44 18 18e-mail: [email protected]
dywidAg-systemsinternAtionAl gmbhmax-planck-ring 140764 langenfeld, germanyphone +49 2173 79 02 0Fax +49 2173 79 02 20e-mail: [email protected]
dywidAg-systemsinternAtionAl gmbhgermanenstrasse 886343 koenigsbrunn, germanyphone +49 8231 96 07 0Fax +49 8231 96 07 40e-mail: [email protected]
dywidAg-systems internAtionAl gmbhsiemensstrasse 885716 unterschleissheim, germanyphone +49-89-30 90 50-100Fax +49-89-30 90 50-120e-mail: [email protected]
Italydywit s.p.A.via grandi, 6820017 mazzo di rho (milano), italyphone +39-02-93 46 87 1Fax +39-02-93 46 87 301e-mail: [email protected]
NetherlandsdywidAg-systemsinternAtionAl b.vveilingweg 25301 km zaltbommel, netherlandsphone +31-418-57 89 22Fax +31-418-51 30 12e-mail: [email protected]
NorwaydywidAg-systemsinternAtionAl A/sindustrieveien 7A1483 skytta, norwayphone +47-67-06 15 60Fax +47-67-06 15 59e-mail: [email protected]
PortugaldywidAg-systemsinternAtionAl ldArua do polo sullote 1.01.1.1 – 2b1990-273 lisbon, portugalphone +351-21-89 22 890Fax +351-21-89 22 899e-mail: [email protected]
SpaindywidAg sistemAs ConstruCtivos, s.A.Avenida de la industria, 4pol. ind. la Cantuena28947 Fuenlabrada (mAdrid), spainphone +34-91-642 20 72Fax +34-91-642 27 10e-mail: dywidag @dywidag-sistemas.comwww.dywidag-sistemas.com
United KingdomdywidAg-systemsinternAtionAl ltd.Northfield Roadsoutham, warwickshireCv47 0Fg, great britainphone +44-1926-81 39 80Fax +44-1926-81 38 17e-mail: [email protected]/uk
Please note: This brochure serves basic information purposes only. Technical data and information provided herein shall be considered non-binding and may be subject to change without notice. We do not assume any liabilityfor losses or damages attributed to the use of this technical data and any improper use of our products. Should you require further information on particular products, please do not hesitate to contact us.
