INDEX. 4. SINGLE WIRE STRAND ANCHORAGES E SERIES Anchorages E Anchorages EX 16

Transcription

1 Post tensioning anchor system English

2 INDEX 1. STRAND 3 2. ACTIVE ANCHORAGES M SERIES Active Anchorages M Anchorages M Anchorages M Accessories for injection on M anchorages 8 3. ACTIVE ANCHORAGES ME SERIES SINGLE WIRE STRAND ANCHORAGES E SERIES Anchorages E Anchorages EX PASSIVE ANCHORAGES D SERIES Passive anchorages D Passive anchorages D PASSIVE ANCHORAGES S SERIES C15 COUPLERS COUPLERS G SERIES Couplers G Couplers G Couplers G application COUPLERS F SERIES COUPLERS K SERIES ELEMENTARY ANCHORAGES METAL SHEATHS ST ELEMENTS FOR CALCULATING LOSSES Instantaneous losses Drop in tension through friction Drop in tension through wedge displacement Deferred losses Drop in tension through relaxation Drop in tension through relaxation Drop in tension through viscosity Evaluation of elongation during tensioning of cables Displacement of clamps on active anchors Displacement of clamps and deformation on fixed anchors Deformation of jacks Tension values on post tensioned strand anchorages 37 page Post Tensioning Rev. H page 1

3 Tensioning values on post tensioned bar anchorages Tension limit for precompressed steels GROUTING Grouting with cap Grouting with plug DISTANCES BETWEEN ANCHORAGES Distances from edges Recesses MS STAY CABLES SYSTEM Adjustable anchorages MSA type Fixed anchorages MSD type BARS TTB bar anchor system EQUIPMENT Hydraulic pump - series TTM-A Hydraulic pump - series TTM 450-A Stressing controllers series TTM 250-A Stressing jacks series TTM Sample pressuremeter S Bar stressing jacks Bar stressing jacks series DD Bar stressing jacks series DX Stressing controller - series TTM-E Stressing jacks series M Jack for extrusions - type M Strand opener jack - type S Wedge jacks type B300KN Injection pump- type T Strand forcing machine- type TTM-S Inserter caps Reel carriers - type B Load cells - series DI SITES 19.1 Sites in Italy Sites Abroad 100 Revision catalogue : H Date issued : January 2005 Post Tensioning Rev. H page 2

4 1 - STRAND STRAND FEATURES Diameter Standard Strand type Rated diameter Rated area Mass Ultimate strength Elastic limit at 1% Relaxation after 1000 h. a 0,7-0,8 f pk mm mm cu g/m kn kn % % 0.5" (T13) 0.6" (T15) BS 5896/80 ASTM A416/98 French Standard and pr EN normal super Quality 270 normal super " (T15) BS 5896/80 normal super " (T15) ASTM A416/98 Quality " (T15) ASTM A779/90 Compact Modulus = 196 +/- 10 kn / mm 2 The strand used for post tensioning is produced by SIDERURGICA LATINA MARTIN S.p.A. in compliance with the law and according to the qualification procedures below: - internal statistical controls; - controls carried out by an official laboratory; - elaboration of results obtained to verify the statistical compliance with the rules contained in the Technical Standards. The techniques used enable the production of stabilised and qualified strand. The advantages offered by this product are: - reduced relaxation; - improved behaviour at low and high temperatures compared with traditional products; - raising of proportional limit to 0,01%; - noticeable reduction in production costs of c.a.p. finished products. Post Tensioning Rev. H page 3

5 2 - ACTIVE ANCHORAGES M SERIES The M system has been designed to meet the requirement of reducing the dimensions of the anchorages and the distance between them. Simulations using calculation programmes and finished parts and laboratory tests have made possible the designing of an anchor which, by spreading the load in a particular way, generates tension in compliance with the law. The experience of the companies in the group in the metallurgical sector guarantees the use of quality materials and suitable production processes. All the anchorage plates are made of carbon steel C40-45 UNI EN 10083/1. Given the chemical composition of the steel, the plate must for no reason be welded to reinforcement structures or supports; every weld is a potential breakage point of the plate under load. Conversely, castings, being carried out using spheroid iron, can be welded to the reinforcement without requiring any particular measures. The centring of the steel reinforcement to the casting by welding is highly recommended. Post Tensioning Rev. H page 4

6 2.1 Active anchorages M The active ANCHORAGES series M is made up of the following parts: casting, anchorage plate, clamps and HDPE fitting to connect the casting to the metal sheath without sudden deviations. Casting The castings have a supporting plane for the turned plate, coupling holes to cap and the ¾"injection inlet. The castings are made of spheroid iron EN-GJS EN-JS-1050 (Italy UNI ISO 4544 GS 500-7, France NF A FGS 500-7, Germany DIN 1693 GGG50, Great Britain BS , ISO R , Japan J.S.I. G 5502 FCD 50) which provides high resistance to stress and, as it can be welded, guarantees greater safety during installation. Anchorage plate The strand is blocked on a separating plate, with conical C40-45 UNI EN 10083/1 steel truncated bores and with either 16NiCr4Pb UNI EN or 9SMnP28 UNI 4838 type steel 7015-T15 clamps. Connection Pipe The connection between the anchorage and sheath is by means of a tube passage which guarantees a correct deviation of the strand, minimizing the loss values. The connection is supplied either in HDPE or steel depending on its use. Connecting to support All the castings have two equidistant slots which facilitate bolting them to the support. Grouting All the castings have a ¾ gas threaded hole for injecting, which enables connecting of the injection equipment we supply. For further details regarding injection, turn to the chapter dedicated to Equipment. Post Tensioning Rev. H page 5

7 2.2 - Anchorages M 15 E H ØI A A x A ØB G Ø F A L C D Type Final load A B C D E F G H I L T15 T15S T15C per cable per cable per cable (kn) (kn) (kn) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) 4M / M / M / M / M / M / M / M / M / M / The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev. H page 6

8 2.3 - Anchorages M 13 E H ØI A A x A ØB G Ø F A L C D Final load A B C D E F G H I L T13 T13S per cable per cable (kn) (kn) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) 7M / M / M / M / M / M / M / M / M / M / The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev. H page 7

9 2.4 Grouting accessories on anchorages M All the castings are supplied equipped with protective covers for the threaded holes. The protected holes are: - ¾ gas hole for grouting - three holes for connecting to cap DD-3050-A type valves fitted with ¾ DD type tubes, L=100 mm and DD-6008 type L=200 mm The three holes for connecting to the cap must remain protected by the covers during the grouting phase which will be removed at the moment the threaded bars are screwed in to hold the cap. The ¾ gas hole for grouting must be protected by a cover during all the grouting phase. This hole can be connected up to: - a PVC tube with relative valve in applications with cap - a corrugated tube with valve for forming moulds using a special connecter The casting is connected to the forming mould by bolts housed in lateral slots, (the head of the bolt must remain buried in the concrete). Post Tensioning Rev. H page 8

10 The castings have the following bores: 4M15, 7M15 ½ threaded grouting hole and only two holes for connecting to cap. 9M15, 12M15, 15M15, 19M15, 22M15, 27M15, 31M15 and 37M15 3/4 threaded grouting hole and three holes for connecting to cap. All the transition cones are made of HDPE and have on the back the wording shown on the casting. We therefore recommend to control compatibility of components before installing. Each cone must be fully screwed down so that the stop is up against the casting. Silicone or glues are not required to be used because the threading is shaped so as to guarantee the seal. All the transition cones have little steps which indicate the internal dimension so as to enable the use of sheaths with different diameters. The cone must always be positioned external to the sheath, cut in the position in compliance with the diameter of the metal sheath used; a suitable binding using PVC tape guarantees sealing against grouting leaking in during the grouting phase. Post Tensioning Rev. H page 9

11 3 ACTIVE ANCHORAGES - SERIES ME A feature of the ME active anchorage series is that they can be replaced after a period of time. They are made up of a M type casting, specifically connected to a HDPE sheath with a transition cone. The cone enables the grouting to remain inside, preventing the same from adhering to the internal walls of the casting, guaranteeing that the cable can be dismantled and at the same time providing a perfect seal. The grouting of the heads for external pre-stressing can be carried out using cementitious mixture, wax or grease. The strands can be nude or protected by grease and HDPE. When using nude strand, provision must be made, in some cases, to use local protection of the clamps with grease. Type Final Load A B C D E F G H L T15 T15S T15C per cable per cable per cable (kn) (kn) (kn) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) 4ME / ME / ME / ME / ME / ME / ME / ME / ME / ME / The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev. H page 10

12 4 MONO STRAND ANCHORAGES SERIES E The E series mono strand anchorage is produced in full compliance with the Italian regulations in force and according to the FIP recommendations. The E series mono strand anchorage comprises the following parts: casting, clamps and HDPE joint for connecting the casting to the strand coated with high density polyethylene. Castings All the castings have holes for connection to the forming mould and set up to receive the connection of a step which separates the anchorage from the mould. All the castings are made of spheroid iron EN-GJS EN-JS-1050 (Italy: UNI ISO 4544 GS 500-7, France: NF A FGS 500-7, Germany: DIN 1693 GGG50, U.K: BS , ISO R , Japan: J.S.I. G 5502 FCD 50), which offers high resistance to stress and, as it can be welded, guarantees increased safety during installation. Wedges Anchorage of the strand is achieved using 7015-T15 type 16NiCr4Pb UNI EN steel or 7017-T15 type 9SMnP28 UNI 4838 steel clamps. Joint The connection between the anchorage and sheath is by means of a transition pipe that guarantees correct sealing of the anchorage. Post Tensioning Rev. H page 11

13 Poket former type DD-7004 Transition pipe type DD-0115C0 Spring Ø150 P.60 wire 6 L.180 mm Nut type DD-9000 Gasket type DD-7025 Anchorage type 1E15 HDPE pipe Strand Post Tensioning Rev. H page 12

14 4.1 - E Anchorages ØE B ØD F H G A C Type Final load A B C D E F G H T15 T15S T15C per cable per cable per cable (kn) (kn) (kn) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) 1E The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev. H page 13

15 The E series anchorages are available in the following versions: - 1E15 anchorage made of sanded spheroid iron. - 1E15-A anchorage made of sanded spheroid iron and coated with anti-rust paint. - 1E15-B anchorage made of sanded spheroid iron, coated with anti-rust paint, and machined for connecting up to polyethylene pipe fitting DD-0115-CO. The rear joint is coupled to the casting by means of a push-fit device that guarantees sealing during the jet grouting phase. DD-0115-CO polythene joint for 1E15-B anchorages, can be assembled only on anchorages machined for connecting. Support for connecting to forming mould DD B without threaded pin for connecting to infill mould. The support can be re-used. Support for connecting to infill mould DD A with threaded pin for connecting to infill mould. The support can be re-used. Post Tensioning Rev. H page 14

16 Nut for support for connecting to infill mould DD-9000 with threaded pin for fixing to infill mould. DD-7025 type Neoprene washers for sealing against infiltrations. Connection to infill mould Connection DD-0115CO can be coupled to coated strand, guaranteeing no infiltration. Cables for single strand cut to size Post Tensioning Rev. H page 15

17 4.2 - EX Anchorages Anchorage EX offers the possibility of installing an anchor completely covered by HDPE so as to guarantee perfect protection against corrosion of all the components used for a long period of time. Connection to infill mould - All heads are equipped with two equidistant holes so as to facilitate fixing to the infill mould by means of two bolts. Accessories - All heads are equipped with a series of accessories which complete the system. In correspondence to the movable parts, protection from infiltrations is guaranteed by suitable sealing. Post Tensioning Rev. H page 16

18 5 PASSIVE ANCHORAGES SERIES D The series D passive anchorage is made up of the following parts: casting, anchorage plate complete with springs and clamps, HDPE connection or steel for fitting the casting to the metal sheath without sudden variations. Casting The castings have a supporting plane for the turned plate, coupling holes to cap and the ¾"grouting inlet. The castings are made of spheroid iron EN-GJS EN-JS-1050 (Italy UNI ISO 4544 GS 500-7, France NF A FGS 500-7, Germany DIN 1693 GGG50, Great Britain BS , ISO R , Japan J.S.I. G 5502 FCD 50) which provides high resistance to stress and, as it can be welded, guarantees greater safety during installation. Anchorage plate The strand is blocked on a separating plate, with conical C40-45 UNI EN 10083/1 steel truncated bores and with either 16NiCr4Pb UNI EN or 9SMnP28 UNI 4838 type steel 7015-T15 clamps. Connection The connection between the anchorage and sheath is by means of a tube passage which guarantees a correct deviation of the strand, reducing loss values to a minimum. The connection is supplied either in HDPE or steel depending on its use. Connecting to infill mould All the castings have two equidistant slots which facilitate bolting them to the mould. Grouting All the castings have a ¾ gas threaded hole for injecting, which enables connecting of the grouting equipment we supply. For further details regarding grouting, turn to the chapter dedicated to Equipment. Series D anchorage Post Tensioning Rev. H page 17

19 5.1 Passive anchorages D 15 E H ØI A A x A ØB G Ø F A L C D Type Final load A B C D E F G H I L T15 T15S T15C per cable per cable per cable (kn) (kn) (kn) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) 4D / D / D / D / D / D / D / D / D / D / The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev. H page 18

20 5.2 Passive anchorages D 13 E H ØI A A x A ØB G Ø F A L C D Type Final load A B C D E F G H I L T13 T13S per cable per cable (kn) (kn) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) 7D / D / D / D / D / D / D / D / D / D / The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev. H page 19

21 6 SERIES S PASSIVE ANCHORAGES The S series single strand anchorage is produced in full compliance with the Italian regulations in force and according to the FIP recommendations. In this type of anchorage the strands, in correspondence with the end, are opened so as to improve adherence to the reinforced concrete. The strands are positioned alternately so as to distribute the stress in the reinforced concrete uniformly. Single strand 1S15 Post Tensioning Rev. H page 20

22 E I H G F C A B D Type Final load A B C D E F G H I T15 T15S T15C per cable per cable per cable (kn) (kn) (kn) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) 4S S S S S S S S / The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev.G page 21

23 7 - COUPLER C15 The C type series of joints are made in full compliance with the Italian regulations in force and according to FIP recommendations. The C type joint enables connecting of cables during construction, for example, of bridges under construction. Coupling is carried out using single strand collars equipped internally with preloaded clamps with a spring device. F+ I E+ I D+ I ØA ØB C+ I Type A B C D E F ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) 7C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / The company reserves the right to change its products and specifications without notice. Post Tensioning Rev.G page22

24 8 - G SERIES COUPLER The G series coupler is made up of the following: casting, anchoring plate and coupler, clamps, metal grip connection and HDPE or steel connection. Casting The castings have a supporting plane for the turned plate, coupling holes to cap and the ¾"injection inlet. The castings are made of spheroid iron EN-GJS EN-JS-1050 (Italy UNI ISO 4544 GS 500-7, France NF A FGS 500-7, Germany DIN 1693 GGG50, Great Britain BS , ISO R , Japan J.S.I. G 5502 FCD 50) which provides high resistance to stress and, as it can be welded, guarantees greater safety during installation. Anchoring plate The strand is blocked on a separating plate, with conical C40-45 UNI EN 10083/1 steel truncated bores and with either 16NiCr4Pb UNI EN or 9SMnP28 UNI 4838 type steel 7015-T15 clamps. Connection The connection between the anchoring and sheath is by means of a transition tube passage which guarantees a correct deviation of the strand, reducing loss values to a minimum. The connection is supplied either in HDPE or steel depending on its use. Connecting to infill mould All the castings have two equidistant slots which facilitate bolting them to the mould. Grouting All the castings have a ¾ gas threaded hole for grouting, which enables connecting of the injection equipment we supply. For further details regarding injection, turn to the chapter dedicated to Accessories. Post Tensioning Rev.G page23

25 8.1 - Couplers G 15 E x E ØA B C D Type A B C D E Ø SHEATH ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) 7G /67 9G /77 12G /85 15G /90 19G /100 22G /105 27G /115 The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev.G page24

26 8.2 - Couplers G 13 E x E ØA B C D Type A B C D E Ø SHEATH ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) 9G /67 12G /77 15G /85 19G /90 27G /100 The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev.G page25

27 8.3 - G Couplers- application Coupler assembled The wedges complete with springs are protected by a steel casing which guarantees its tightness. Coupler The coupler is made up of a forged plate provided with tensioning and gripper bores. Gripping of the strand is achieved by means of a spring device that holds the strand once inserted in the external bores. Coupler tensioned Coupler 19G15 being tensioned Post Tensioning Rev.G page26

28 The «G» type anchoring plates are forged out of C40-45 UNI EN 10083/1 steel and provide high machining features to the item, in particular reducing all the possible problems of defects connected with rolling the material. The plates are provided with a rear recess where a steel cover contains the springs and wedges. The cover is fixed to the plate by special screws which guarantee correct attachment and suitable resistance to feeding by the strand feeder. The cover is fitted with a ½ threaded collar which allows correct connection to the injection devices. The discharge on the cover guarantees correct filling of the rear part and protection for the blocking devices. All couplers are guaranteed to be traceable and identifiable. Post Tensioning Rev.G page27

29 The front fitting of the DD-CU type coupler made of HDPE Coupler 19G15 Fitting for coupler DD 1915CU Post Tensioning Rev.G page28

30 9 - F TYPE COUPLERS A B 50 G D D L + s > 300 1T15 2T15 3T15 4T15 F 50 E E (*) E = 45 + n x B E C E Type Final load A B C D E F G 0,6" nor 0,6"sup 0,6"com for cable for cable for cable (KN) (KN) (KN) (mm) (mm) (mm) (mm) (mm) (mm) (mm) 1F (*) The company reserves the right to change its products and specifications without notice. Post Tensioning Rev.G page29

31 10 COUPLER K SERIES The K series single strand anchorage is produced in full compliance with the Italian regulations in force and according to the FIP recommendations. These connections have been studied for post tensioning of tanks or circular structures. The K series connection carries out the role of active and passive head in the case of circular cables, whereas it is a classic coupler for cables in slab. They can be tensioned using M and TTM series jacks using a special curved device that allows a controlled deviation of the strand. The device is made up of steel sectors, the number of which varies according to the deviation angle required; as the angle varies, so does the loss of tension, which must be evaluated through experiments for each individual case. Type A B C D E F G H ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) ( mm ) 2K K K K K The company reserves the right to change its products and specifications without notice. Post Tensioning Rev.H page 30

32 11 ELEMENTARY ANCHORAGES This series of wedges studied for anchorage single or multiple strand to anchorage plates is made for single use and is available for different applications. Wedges for post-tension used on single use anchorages T15 type, 6NiCr4Pb UNI EN steel clamps T15 type, 9SMnP28 UNI 4838 steel clamps Wedges T15 Conical bushes complete with markings for post-tension use in tensioning strand from 15.2 to 15.7mm. Bushes 7010-T15 C40-45 UNI EN 10083/1 Bushes T15/T13 Conical spherical bushes complete with markings for post-tension use in tensioning strand from 15.2 to 15.7mm. - Bushes 7020-T15 C40-45 UNI EN 10083/1, Spherical bushes T15/T13 T15 coupler connections for strand Grip extrusions T15 Grip extrusions. - Bushes T15 C40-45 UNI EN 10083/1, - T15 type 9SMnP28UNI483 steel shells Sleeves for post-tensioning used on strand couplers T15 type sleeve with 12NiCr3Pb UNI EN steel wedges, T15 type sleeve with 9SMnP28 UNI 4838 steel wedges. Post Tensioning Rev.H page 31

33 12 CORRUGATED METAL SHEATHS ST The metal sheaths are the most inexpensive way for creating vacuums in post tensioned elements because they supply good secondary protection against corrosion and an excellent constraint between the cables and the concrete. The primary protection against corrosion is given by the alkalinity of the injection and the concrete itself. The sheaths are available in different versions and are produced in cold rolled Fe P01 UNI 5961/67 steel clinched sheet. The characteristics may vary in: - Diameter - bar length - thickness of sheet steel used On request they can be supplied galvanised. The sheaths are supplied in bundles; on each bar is assembled a connection sleeve external to the bar. Corrugated sheaths recommended for use with strand T15 and T15S Number strands Internal diameter Injection cement Rectilinear part Minimum Radius after curvature (mm) Litres/meter Cement Kg/meter Minimum (mm) Minimum (mm) ,2 1, ,3 3, ,8 4, ,6 5, ,8 6, ,7 7, ,2 8, ,2 9, ,6 13, The thicknesses of the sheaths may vary from 0.3 to 0.6 mm. The dimensions in the table are indicative and must be compared with the operating instructions for each individual project. Post Tensioning Rev.H page 32

34 13 LOSS CALCULATION ELEMENTS In order to carry out calculations it is necessary to distinguish between immediate and deferred drops in tension. Are divided into : - Loss due to friction - Loss due to inserting of wedges - Loss due to elastic deformation of the concrete They occur during the stressing phase, reducing the tension generated by the jack Immediate losses In compliance with CEB-FIP Model Code dated 1990 the tensions σ ( x) Loss of tension due to friction po, in a specific section placed at an x distance from the active head, is reduced with respect to the tension σ po,max. ; the difference between the two tensions corresponds to the loss by friction. The value of σ po ( x) is calculated using the following formula: po ( x) σ = σ po, max. e ( fα + Kx) where : e = base of Neperiano logarithm f = friction coefficient α = sum of angular calculations calculated up to section x, evaluated in radians K = conventional deviation of the rectilinear cable per linear meter. σ x = tension in the section with x coordinate po ( ) σ po = tension at the active anchoring level Post Tensioning Rev. H page 33

35 In the case of internal post-tension f = 0,55 steel/concrete f = 0,30 steel/concrete BS 8110 f = 0,25 steel/galvanised steel f = 0,18-0,22 strand Euro code 2) 0,005 < K < 0,010 rad/m In the case of external post-tension For saddles with curvature radius between 2.5 and 4 m it can be assumed that: K = 0 0,25 f 0,30 strand on metal saddle 0,20 f 0,25 greased stand on metal saddle 0,05 f 0,07 bundle of strand individually coated on metal saddle 0,12 f 0,15 nude strand in HDPE sheath,, on metal saddle Loss of tension on inserting wedges During the blocking of the wedges in the anchoring, the loss of elongation of the strand is damped by friction with the sheath; this is the opposite to what happens during the stressing phase. The loss of tension, which reaches its maximum in correspondence with the anchoring, progressively and symmetrically decreases and stops at a d distance from the anchoring. p(x) σp0g(x) σ'p(x) d x distanza dall' ancoraggio Distance from anchoring Fig. Tension along the cable and following wedging of the clamps. d = σ po g E p fα + K l fα σ po = σ po 2 d + K l Post Tensioning Rev. H page 34

36 13.2 Deferred losses They are divided into : - Loss due to shrinkage - Loss due to viscosity - Loss due to relaxation of the steel They occur during the life of the work caused by phenomena strictly connected to the behaviour of the concrete (shrinkage and viscosity) and the steel Loss of tension due to relaxation The high resistance steels, subjected over a period of time to constant tension, undergo stretching. The final loss of tension value depends on the duration of the post-tension application. To determine the overall loss due to relaxation we suggest the following formula where: 6 σ pi σ = ϕ p f pk ( x) µ σ ( x) ϕ 1000 relaxation value guaranteed by the producer at 1000 hours σ value in initial tension in the section placed at x distance pi pk ( x) f yield point of the strand µ o =0,43 for low relaxation strand =0,30 for medium relaxation strand pi Loss of tension due to shrinkage Shrinkage is a phenomena tied to the shrinkage of the concrete that occurs during hardening. As the post-tension cables are closely connected to the concrete matrix, they are subject to the same deformation variations. The final losses of tension due to shrinkage, in the case of constant thermohygrometric conditions, depend on the age of the concrete at the moment of tensioning. The mathematical formula that expresses this connection is: where f r = Ε Ε p = elastic modulus of the strand ε r = final deformation due to shrinkage p ε r Post Tensioning Rev. H page 35

37 Loss of tension due to viscosity Deformation due to viscosity is due to a shrinkage of the concrete which is in relation to the time and level of tension. The final losses of tension due to shrinkage, in the case of constant thermohygrometric conditions, depend on the age of the concrete at the moment of tensioning, and also to the duration and intensity of the load applied. Slow deformation under load, save more precise evaluations, must be assumed to be twice the elastic deformation, always given that the structure is stressed not prior to 14 days of maturing Evaluations of elongations during tensioning of cables During tensioning of cables it is necessary to compare the actual elongations with the theoretical elongations envisaged in the calculations to which the corrective terms must be added in order to obtain the true elongations. The elongations registered on site are the sum of the following elements: Lo = L a + L b + L c + L d L a = elongation of the strand calculated considering the extra length necessary for the jack to grip it. L b = elastic deformation of the concrete. Usually, the elongation measured on the jack included the elastic shrinkage of the concrete L c = sum of the deformations of the anchoring devices and re-entry of the clamps in the conical seats = re-entry of gripper clamps and internal deformations of the jack L d Draw-in of wedges on the active anchoring The loss of elongation due to draw-in of the wedges occurs during the locking phase of the same following tensioning L d = 3-4 mm for tensioning with jacks equipped with wedging system L d = 12 mm for tensioning with jacks not equipped with wedging system, series MX Re-entry of clamps and deformation of fixed anchoring Usually, deformation of anchorings under load is always limited to and does not exceed 1mm. Draw-in of wedges on passive anchorages causes a translation of the cable towards the tensioning jack. The values remain about 4-5mm. Post Tensioning Rev. H page 36

38 Deformations of jacks These deformations must be assumed from the measure of the elongation of the strand when the readings have been taken on the piston of the jack. The internal losses at the jacks are considered: jacks series TTM jacks series M jacks series MX jacks series DD = 8 mm = 7 mm = 9 mm = 4 mm When the elongations are taken directly on the strand these values must not be taken into consideration Tensioning values on strand post-tensioned anchorings (Ministerial Decree 9 January 1996) Technical standards for calculations, carrying out and testing of the reinforced concrete, normal and precompressed structures and for metal structures. Maximum load applicable on single strand Maximum tensioning pull ( Pi ) must be limited to: Pi = 0,85 x f p(1)k x nominal Area Pi = maximum load in KN Strand characteristics Diameter Standard Type of stand Nominal diameter Nominal area f ptk f p(1)k Mass mm mm 2 N/mm 2 N/mm 2 gr./m Tension 1% elong. KN Yield point (Ptk) Elastic limit at 0,1% Pt0,1k ) Relaxation after 1000 h.0,7-0,8 f pt KN KN % % (T15) pr EN (T15) ASTM A779/00 pr EN normal super Compact Elastic modulus = 196 +/- 10 KN / mm 2 Post Tensioning Rev. H page 37

39 Tensioning values on bar post-tensioned anchorings (Ministerial Decree 9 January 1996) Technical standards for calculations, carrying out and testing of the reinforced concrete, normal and precompressed structures and for metal structures. Maximum pull applicable on single bar Maximum tensioning pull ( Pi ) must be limited to: Pi = 0,85 x Fpyk Pi = maximum tensioning pull in KN Tensioning limits for pre-stressing steel (Ministerial Decree 9 January 1996) Technical standards for calculations, carrying out and testing of the reinforced concrete, normal and precompressed structures and for metal structures. The tensions must be limited to the following values refer to those characteristics guaranteed by the producer. Post-stressed casing structure: wire or braid strand bars σ σ sp σ σ σ σ sp spi spi spi sp 0,85 0,60 0,85 0,60 0,85 0,60 f f f f pyk ptk f f p(1) k ptk p(0,2) k ptk Pre-stressing steel f py yield tension ( bars ) f p(1) tension at 1% of deformation under load f p(0,2) tension at 0,2% of residual deformation f pt characteristic tension f pyk characteristic yield tension (bars) f p(1)k characteristic tension at 1% of deformation under load f p(0,2)k characteristic tension at 0,2% of residual deformation f ptk characteristic yield tension Post Tensioning Rev. H page 38

40 14 - GROUTING Grouting of the anchorings can be carried out using different technical solutions which must be clarified with the Company before starting work on the site. The cap is made up of a cover equipped with a seal fixed to the casting by means of suitable tie rods which vary in length and size depending on the different applications. A special closing disc tightens the seal and the cap to the grouting. The disc guarantees the possibility of turning the cap to the most suitable position and such so as to allow all the air to exit. For the accessories refer to the appropriate chapter. The most used system for carrying out grouting is by re-usable caps. This system allows homogenous infilling without air bubbles both when using the M and G anchoring series. Grouting must be carried out at temperatures of not less than 5 C and the following water cement-additive ratio must be adhered to: - 50 Kg cement - 20 litres of water, gr. additive The applicable grouting systems are : - infilling of heads, - use of reusable caps - use of mono use caps. Internationally the system using caps is coupled with the vacuum technology to improve the grouting. A suitable range of accessories guarantees the maintenance of pressure in the recess and complete discharge of the air. Grouting cap on coupler 19G15 Post Tensioning Rev.H page 39

41 14.1 Grouting with cap A metal cap, complete with seal, confines the grouting to the anchorage plate side. The grouting is through the ¾ hole in the casting in which the connection is inserted. The connection for the grouting is a valve that can be connected either to the corrugated polyethylene tube or a rigid threaded ¾ tube. After use the cap is removed and saved. Post Tensioning Rev.H page 40

42 14.2 Grouting Grouting of the head is the most economic system for grouting the cable which is always carried out through the ¾ hole by inserting either the corrugated or rigid PVC tube according to requirements. Grouting Connection using a HDPE corrugated tube tin which the valve is inserted. Post Tensioning Rev.H page 41

43 Re-useable valve type DD-3050-A diam. 25 mm. This valve enables interception of the mixture, it can be connected directly to the DD20x25 diam. 25 mm corrugated tube and is re-usable if the conical shut-off part is greased. Valve type DD-3050-A Gate valve type DD-1003-A diam. 25 mm This valve enables interception of the mixture, it can be connected directly to the DD20x25 diam. 25 mm corrugated tube and is usually used to close the bleed tube. Valve type DD-1003-A Gate valve type DD-1016-A diam. 20 mm This gate valve can e connected to the 20 mm diam. type DD15x20. corrugated tube. Valve type DD-1016-A Post Tensioning Rev.H page 42

44 Re-useable valve type DD-3050-A connected to corrugated tube type DD 20x25. This valve is used for primary groutings; considered to be re-usable 4 times if appropriately greased on the inside. Valve type DD-3050-A with tube DD20x25 Re-useable valve type DD-1003-A connected to corrugated tube type DD 20x25. This valve is used for primary bleeders; considered to be re-usable twice if appropriately greased on the inside.. Valve type DD-1003-A with tube DD20x25 Re-useable valve type DD-1016-A connected to corrugated tube type DD 15x20. This valve is used for secondary bleeders; considered to be re-usable twice if appropriately greased on the inside. Valve type DD-1016-A with tube DD15x20 Post Tensioning Rev.H page 43

45 Corrugated pipe for grout and vent - DD 20x25 diam. 25 mm corrugated tube for primary injections and bleeders - DD 15x20 diam. 20 mm corrugated tube for secondary vent Corrugated tube type DD 20x25 o DD15x20 Threaded rigid PVC tube sections - Threaded tube sections L=200 mm ¾ type DD Threaded tube sections L=100 mm ¾ type DD Threaded tube sections L=200 mm 1/2 type DD Threaded tube sections L=100 mm 1/2 type DD-6007 Rigid PVC tube type DD-6010 e DD-6009 Rigid PVC tube type DD-6010 and DD-6009 with type DD-1017-A connection Post Tensioning Rev.H page 44

46 Connection: - Re-usable valve type DD-3050-A, - Connector type DD-1017-A, - Threaded tube sections L=100 mm ¾ type DD-6009 Type DD-3050-A valves coupled with ¾ type DD-6009 L=100 mm tubes and type DD-6008 L=200 mm Connection: - Re-usable valve type DD-1003-A, - Connector type DD-1017-A, - Threaded tube sections L=100 mm ¾ type DD-6009 Type DD-1003-A valves coupled with ¾ type DD-6009 L=100 mm tubes and type DD-6008 L=200 mm Post Tensioning Rev.H page 45

47 Connector type DD-1017-A for coupling between: - ¾ threaded tube sections type DD and DD-6010, - valves DD-3050-A and DD-1003-A, Connector type DD-1017-A Connector type DD-1017-B for coupling between: - corrugated tube DD20x25 mm, - female ¾ coupling Connector type DD-1017-B Connector type DD-1033-B 1/2" corrugated tube DD15x20 Connector type DD-1034-B 1/2" corrugated tube DD20x25 Connector type DD-1033-B and DD-1034-B Post Tensioning Rev.H page 46

48 Connector type DD-1033-B 1/2" corrugated tube DD15x20 mm - Connector type DD-1017-B and corrugated tube DD20x25 mm - Connector type DD-1033-B 1/2" corrugated tube DD15x20 mm - Connector type DD-1034-B 1/2" corrugated tube DD20x25 mm Connector type DD-1034-B 1/2" corrugated tube DD20x25 mm Connector attachment to casting M Attachment to castings series M Connector type DD-1034-B and DD-1033-B Anchorings: 4M15 and 7M15 connection series DD-1034 Anchorings: 9M15 12M15, 15M15, 19M15 22M15, 27M15, 31M15 and 37M15 connection series DD-1017-B Post Tensioning Rev.H page 47

49 Check nuts for threaded connectors: Nut DD-9000 for coupling with ¾ thread Nut DD-8000 for coupling with 1/2" thread Connector type DD-1033-B corrugated tube DD15x20 mm. and check nut DD-8000 Connector type DD034-B 1/2" corrugated tube DD20x25 mm. and check nut DD-8000 Type DD-1001 cover made of soft material so as to fit on all the sheath sizes. The item is mono use. Connector series G with coupling for injection Bleeder cover type DD-1001 Post Tensioning Rev.H page 48

50 15 DISTANCES BETWEEN THE ANCHORINGS 15.1 Distances from edges A B 2A A B A B Minimun anchorage centres (mm) A Minimun edges clearances (mm) Type fc min fc min Type M M M M M M M M M M M M M M M M The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration Post Tensioning Rev. H page 49

51 15.2 Recess C a B x B A B x B A x A a 4M15 7M15 9M15 12M15 15M15 19M15 22M15 27M15 A x A B x B C a The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration The fixing of the heads to the forming mould must guarantee a perfect seal to avoid the concrete entering the recess during injection grouting. The heads are supplied with turned supporting planes. If the coupling surfaces with the anchoring does not provide an adequate seal for the system, rubber or silicone seals will have to be used. Post Tensioning Rev.H page 50

52 16 MS STAY CABLES SYSTEM The MS stay cable system is the result of years of experience in the metallurgical sector. The research into better materials, coupled with production cycles so as to guarantee a very high level of purity of the material, has led to the achievement of high performance of the anchorages, able to meet the highest fatigue standards required by international regulations. The metallurgical experience of the companies in the group has enabled the MS anchorages to receive the best materials, the best heat treatments, the best protective coverings available on the market today, all elements which give the anchorage excellent mechanical-structural features, to guarantee the structures where they are installed, very high strength and preservation over the years. Steels The steels used in making the anchorage are very high quality and vacuum cast, with tests for inclusions carried out with the best control systems the market can offer. All the heads are made of forged steel and checked using non destructive systems, so as to ensure the pureness of the material, an essential quality for elements as important as anchorage for stays. Treatments All the materials used in producing anchorages are normalized and stabilized following special treatments, so as to guarantee very high performance of the materials used over the years. Surface protection Protection of the surfaces of the anchorage head can be further improved by special protective treatment against corrosion, which is NIPRE, that guarantees resistance against rust in saline fog, four times higher than chrome. NIPRE is a surface treatment that improves the characteristics of the items, increasing the surface hardness characteristics, improving the friction coefficient and giving the item a grey metallic colour, characteristic of the treatment. The surfaces do not change their measurements and there is no addition of material, an important feature for elements undergoing fatigue. Anchorages The MS series has two types of anchorages: - active anchorage MSA - passive anchorage MSD The anchorage system for the MS stays is a mechanical anchorage protected by injections of wax in the anchorage zone of the strand. The stand used is T15S 15,7 mm. Galvanised, waxed and protected with a coating of high density polyethylene. The anchorages are tested for a load varying from 150 N/mm 2 to 200 N/mm 2. The active anchorages are prepared for adjustment using a toroidal jack, a ring nut is available for accurate adjustment of elongation of the whole cable. Sheaths The sheaths used to protect the stays externally may be: - HDPE (polyethylene), - Stainless steel, - Aluminium. The sheaths are the external protection of the cable and the choice must be made in agreement with the architectonical requirements of the project. The sheaths are coupled with anti-vandalism tubes that protect the anchorage-sheath connection at the end section of the cable. Post Tensioning Rev. H page 51

53 16.1 Adjustable type MSA anchorage The MSA adjustable anchorages are made using an anchorage plate placed on a threaded pin, which coupled with a ring nut, enables adjustment to be carried out during anchorage. The adjustments are reached by tightening or loosening the ring nut using a special toroidal jack of adequate capacity. The length of the threaded pin varies depending on the adjustments required by the project. Inside the regulating pin there is a space to contain wax or grease to protect the parts of the strand not covered by the HDPE protection. The head has a deviator complete with damper, made to deviate the strand inside the sheath and at the same time to dampen the vibrations the cable is subjected to. A protective cap cover all the head protecting it from corrosion. Type A B D E F G H (mm) (mm) (mm) (mm) (mm) (mm) (mm) 19MSA15 140/ / x MSA15 180/ / x MSA15 200/ / x MSA15 225/ / x MSA15 250/ / x MSA15 280/ / x MSA15 315/ / x MSA15 315/ / x MSA15 355/ / x The company reserves the right to change its products and specifications without notice. All documents are in compliance with the Memorandum dated 15 October 1996 n 252 AA.GG./S.T.C. and have ministerial registration. Post Tension Rev. H page 52