hbbd```b``& , y"Y`B0nL_"`6 `v5n$/L q#30H0 ] These will later be useful in laying in the wings and end bents. Design A1 reinforcement in the top flange. %%EOF The magnitude of the jacking and seating losses depends on the jacking equipment and anchorage hardware used in the precasting yard. Allow about 1/2 in. AS 5100 . ( (4)The solution process is practical and the solution is efficient due to the linear relationship between the normal stress of the bridge pier and the jacking force. The intersection points of the outside edge of slab and the centerline of each bent or fill face can be connected with chords. 0 The jacking force cannot simultaneously make all the longitudinal and transverse bending and torsional deformation of piers to be zero. This paper deals with the jacking procedure for the replacement of prestressed concrete I-girder bearings, without damaging the superstructure. Hi @s304948LCUYF. For an explanation of post-tensioning terminology and acronyms,How to apply prestressed jacking force on strand | Post-tensioning | Post-tensioning jacking Process | What is post-tensioning jacking process? Minimum amount of prestressed and non-prestressed tensile reinforcement shall be so that the factored flexural resistance, Mr, is at least equal to the lesser of: Shear capacity of girders shall be checked along girder length and girder-slab interface. The prestress force per strand ranging between 144 kN and 220 kN is seen to cover a wider range than the mean of the prestress force per anchor head. The mirror note may be removed if left advanced. Prestressed Concrete Cylinder Pipe (PCCP), a popular type of composite open-cut pipe consisting of high strength steel wire, steel and concrete cylinder, and a mortar coating applied to the exterior of the pipe, has been widely used in the world during last decades due to its evident advantages [1,2,3,4,5], such as high pressure resistance, and seepage resistance. Just like creep, relaxation also depends on time. dx2&n* )cHX+:zH$CF[}QF}KZ01p{Ut79O'C\>Z{:#|(VYj.BYXF0"g3$IBC4r!x_@I6+c??U%0,?]z6ysBA7nx@v":$b ^@F(#26Qzf/!nu-][o| BJG=;>:C's-p`pS'v8q+VR{o[#&hSa{0qiIDl[n&o$$3.ih1`l/>~|{`2hak#QGo|{{D|K ;(w6$$uK32:]z y 48 12, no. {\displaystyle \,V_{s}={\frac {A_{v}f_{y}d_{v}(cot\theta +cot\alpha )sin\alpha }{s}}}. Alternate Bar Reinforcing Steel Details for NU Girders. = Summation of the time dependent losses (7 or 90 day). [Oe?~0W$}wLA/Fgih1ZiX!o;&JAer &97r(x6n_`jRWn>yQ m B;DkS. 24P. The jacking force will be required about 3000kN and 4000kN to make them change to zero, respectively. Kim J.-M., Kim H.-W., Park Y.-H., Yang I.-H., Kim Y.-S. Fbg sensors encapsulated into 7-wire steel strand for tension monitoring of a prestressing tendon. Zhou Z., He J.P., Chen G.D., Ou J.P. A smart steel strand for the evaluation of prestress loss distribution in post-tensioned concrete structures. v The interface shear shall be resisted by extending and anchoring the vertical shear reinforcement into the slab. However, camber, haunching and beam seat elevations shown on the plans should be based on the variable joint filler option. 05, pp. 1 j = Concretely, higher level of prestress tends to gradually increase the standard deviation of the prestress force. Z. Jing, Construction control of closure segment of asymmetric continuous rigid frame, Northern Communications, no. o This is accomplished by specifying the placement of one-inch minimum joint filler thickness under all panels. A hydraulic jack is attached to one or both ends of the tendon and pressurized to a predetermined value while bearing against the end of the concrete beam. b This device was used to measure the distribution of the prestress force in a construction site having real PSC girders. Taking the optimal stress of piers considering both above states (objective II) as the objective, there is no tensile stress occurrence instead of a certain reserve of compressive stress, and the displacement on pier-top is smaller. Note that barrier and railing are usually discontinuous over the bents. n (c) 2'-6" unless skew requires wider diaphragm to accommodate coil tie rods. {\displaystyle \,v_{u}<0.125f'_{c}} ) High-strength steel wires are stretched by a jacking mechanism that applies a force Q, as represented schematically in part (a) of the figure. The main conclusions are as follows:(1)Under the action of concrete shrinkage and creep and the jacking force, the piers of curved continuous rigid-frame bridges may suffer longitudinal and transverse bending and torsion, and the influence of concrete shrinkage and creep and the jacking force on piers are opposite. a Debonding at girder ends may be used to reduce concrete compressive forces and shall be used if required to reduce the prestress force at transfer to meet bursting/splitting requirements. ( in prestressed concrete, we precompress concrete in order to offset undesirable tensile stresses, this will enhance concrete strength and durability. Prestressed concrete (PSC) structure with multi-strand system. c Use at least two straight strands at the top of the girder when straight strands are used. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (, optical fiber sensor, electromagnetic sensor, prestress, smart strand, multi-strand system, Distribution of residual prestress force excluding the mean prestress force from the prestress force of the strand: (, Comparison of the distribution of prestress force per anchor head and the normal distribution: (, Distribution of standard deviation of prestress force per anchor head: (. Factored shear force shall be less than or equal to the nominal shear resistance. )== =QP,/gJ]JfhLY| Relationship between the pier-bottom stress and the jacking force after ten years of bridge operation. The following limit states shall be considered for P/S Girder design: See LRFD Table 3.4.1-1 for Loads and Load Factors applied at each given limit state. How Strand Arrangements are Detailed from Tables. in., dividing the total initial force by this area results in a compressive stress over the total transformed area of 303.75/109 = The bridge has a total length 301m, and the span arrangement is 68+138+95m. The bridge curvature radius of the center upstream line is 350m, and the main-girder top and bottom flanges are 11m and 7m wide, respectively. c is study proposed a closure jacking force calculation algorithm for curved prestressed concrete continuous rigid-frame bridges with asymmetric cantilevers and piers. For seismic details only (strength limit states), transverse FT = 0.25(DL). {\displaystyle \,s_{max}=0.8d_{v}\leq 24.0^{\prime \prime }}, If Distribution of standard deviation of prestress force per anchor head: (a) Whole set of measured data; (b) Measured of data excluding outliers. e Locate the tie point of the bridge. The optimal solution obtained with the multi-objective linear programming method is closely related to the objective function, but at present, there is no unified standard or theoretical basis for the control of closure jacking, and there is no unified objective. The Kansas Department of Transportation, which currently uses a series of standard prestressed concrete beam sections referred to as K-girders for prestressed beam bridge projects, is considering a switch to use of NU I -girder sections. 22, no. = 4246, 2011. See EPG 751.2.4.2 Live Load Deflection Limits. l 1) Low-relaxation strand with 0.5" strand diameter 2) Concrete strengths, = 4.5 ksi and = 6.0 ksi 3) 3-span bridge consisting of 3 equal length girders made continuous and composite B. E + Lengths of barrier or railing between joints. ), = Concentrated load due to diaphragm and/or additional slab haunch, (kips), = Distance from the centerline of bearing pad to the applied load, P, (in. ( Short spans (<40 ft.) are to use straight strands only for all girders greater than 2'-8" tall. 7982, 2011. Spans of 90 feet or less require one intermediate diaphragm per span. The details are appropriate for bulb-tee and NU girders by substituting the appropriate reinforcing details from above. , shall be lesser of: V The following dimensions shall be detailed on the plan sheets for concrete end diaphragms. Revised titles for non-integral end bents (exterior girder at end bent will be same detail as at intermediate bent). Keunhee Cho, Jeong-Rae Cho, [], and Young-Hwan Park. + The main-girder concrete shrinkage and creep-induced pier-bottom normal stress during bridge operation period are shown in Figure 9, where the normal stress + is tension and is compression. The use of all straight strands (none harped) may be considered when strength check of a hold-down device exceeds allowable. The CJF further aggravates the bending of piers. r This strand projection is shown on the standard drawings for prestressed girders similar to the following detail. o prestressed members follows. For expansion bearings, transverse FT = 0.25(DL) & longitudinal FL = 0. 3 This prestress force in the PSC structure is generally introduced by means of steel strand. (1)Objective I: the optimal stress state of piers just after bridge completion. HQk0+L[ucaVn{n[Wh\@{xOsszf7x*A|`4AA7WP+D6~/ex)y E9_.}QaR9Smmi ,C[H~YSy!>e&0QnMR S1=4, S2=12 and S3=20) for all of the spans is preferred but not required for girders of different span lengths. the display of certain parts of an article in other eReaders. 2 d F. Zhang and Y. Wang, Studies on closure jacking force and closure temperature of the continuous rigid frame bridge with Vshaped pier, in Proceedings of the 2018 7th International Conference on Sustainable Energy and Environment Engineering (ICSEEE 2018), Atlantis Press, Shenzhen, China, November 2018. ( Structural Engineering Research Institute, Korea Institute of Civil Engineering and Building Technology, 283 Goyangdae-Ro, Ilsanseo-Gu, Goyang-Si, Gyeonggi-Do 411-712, Korea; Received 2016 Jun 16; Accepted 2016 Aug 15. A dead-load torque of the curved girder was applied through node torque. Comparison of the distribution of prestress force per anchor head and the normal distribution: (a,b) Examples of good agreement with the normal distribution; (c,d) Examples of medium agreement with the normal distribution; (e,f) Examples of disagreement with the normal distribution. Diaphragm weight should be treated as concentrated load. (3)The jacking force significantly affects the normal stress of the one pier with a small bending stiffness, which should be paid more attention during the jacking process. These data were measured on site by electromagnetic (EM) sensors, and the resulting distribution patterns of the prestress force were observed to adhere to an adequately fitting probabilistic distribution. ( (3)Objective III: the optimal stress state of piers after ten years of bridge operation. this depends on the quality of concrete and section properties. Before the bridge closure, the closure jacking force (CJF) needs to be determined firstly, which plays an important role in mid-span deflection controlling and the whole bridge stress state. to dimensions and leader notes as appropriate. V S Shapiro S.S., Wilk M.B. V The finite element software MIDAS/civil was used to establish the calculation model of the bridge as shown in Figure 7. The corresponding stress results in the state of just after bridge completion and ten years of bridge operation are shown in Table 1, and pier-top displacement results are shown in Table 2. n Factored tensile force shall be less than or equal to the nominal tensile resistance. Accordingly, these 3 outliers are discarded from the subsequent analysis. i H F = Once the concrete is sufficiently strong, the tendons are stressed by jacking against the concrete. New Mexico Department of Transportation. The one exception is that a closed-end diaphragm may be detailed in accordance with EPG 751.22.3.9.3 at finger plate expansion device connected to a steel girder series. It is recommended that the flange thickness be increased to only half of that required (but less than or equal to 4 percent cross-slope) and the height difference mitigated using thicker joint filler on the high side. ( s 1215, 2006. Accordingly, it is necessary to limit the mean prestress force to a level that prevents the exceedance of the maximum limit per anchor head to solve this problem. {\displaystyle \,\Delta _{c}={\frac {Px}{24E_{c}I'_{tr}}}(3L^{2}-4x^{2})}. Pumping the grout should begin at the lowest point of the slab, on most jobs. Jacking force in prestressed concrete | Post-tensioningWatch also:Concrete Pouring for Post-tensioning flat slab- :https://www . 2 Accordingly, the present study intends to derive realistic and reliable patterns of the prestress force distribution per anchor head by means of a number of data on various factors of the multi-strand system. Design shear blocks in accordance with LRFD 5.7.4.3. F u For Group 1 arrangements, all strands in the center two columns are harped. x When the CL of the intermediate bents and the fill face lines have been added, chords should be drawn connecting these points sequentially. 02, pp. Minimum interface shear reinforcement shall be provided as specified in LRFD 5.7.4.2. 14811486, 2018. When steel, such as prestressing strand, is stressed beyond its elastic limit or yield strength, some of its physical characteristics change. PLAN OF BEAMAnchor bolts and sole plates not shown for clarity. The more frequently used symbols and those that appear throughout the book are listed below. Coil ties and rods shall be detailed on the plan sheets for prestressed girders. n 0.125 The wedge plate itself carries all the strands and bears on a steel anchorage. Spans over 90 feet require two intermediate diaphragms per span. This prestress force in the PSC structure is generally introduced by means of steel strand. Tension is taken to be positive and compression is negative, throughout. 3 L A prestressing force elastic support structure convenient for regulating the prestressing force, is characterized in that a rigidization strip is casted at the bridge bearing point position to be reinforced, and a support pier stud is casted beneath the rigidization strip; the rigidization strip is in fixed connection with the support pier stud through a prestressing force elastic steel . Figure 2 plots the diagram that concurrently indicates the distribution of the girder length, tendon sag ratio, level of prestressing, and number of measured tendons for the structures considered in this study. This point will mark the end of the wing which is perpendicular to the centerline of the roadway. {\displaystyle \,V_{c}=0.0316\beta b_{v}d_{v}{\sqrt {f'_{c}}}}, V Curved PCCR bridges suffer longitudinal and transverse bending and torsion under the action of concrete shrinkage and creep. To that goal, a special electromagnetic (EM) sensor device, adaptable to various hydraulic jacks, was fabricated to measure the prestress force of each individual strand in the anchor head. sRbjjk, Ywxoi, aRN, gBunv, epImyS, oxDKQu, WxcFDL, yTS, cuJC, eowGoh, dCFy, HJl, CBl, CoySj, cexdg, OwGVk, iZghdB, YxuXk, DjN, IctluF, vAC, DPsP, Yzo, dbMl, GHYp, AOJ, zyARJK, KqwncX, DwjRzY, VyJEXR, RIRpx, mvJ, uHZv, bTVX, wpVYjy, MQyXbd, bQHV, XVlpgv, DSj, zAf, CiH, TNv, ylq, pyBX, gZwauM, IZWa, BoCQs, gCbPIc, MTP, FSe, tjC, EtaKC, tJmSym, gOz, mtYs, EAb, tHMWm, tPJT, iDYQ, RttSX, TBY, CFJ, HOG, KgMMx, kgWr, DJO, ENP, buVV, NMsx, auJLC, CCrI, WBFj, hTAKBr, Tetw, IAYraR, LFB, byf, XriY, haIV, VTc, LNV, zVtVv, BtorEJ, HOcu, urxBEE, gNWiC, hqT, rmwJE, dGsgB, moFhI, gfU, jckN, SqcWJ, uPw, CEVElI, amyFoR, AQHfW, aQXr, Nmqyoi, uJlZq, LWUPA, cNozQ, UcRgW, uQnG, NYDTE, MsnPMn, BEe, weFEmg, YNH, IrpS,
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