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1、后张法简支箱梁预应力施工工艺（Prestressed construction technology of simply supported box girder with post tensioning method）The construction technology of post tensioned prestressed beam simply supported boxChina Railway nineteen Bureau Group Fifth Engineering Co., Ltd. Xinxiang beam fieldKey words: three control
2、, strength, elastic modulus, age, stress, tension control, periodic verification, calibration, check before useAbstract: post tensioned prestressed box girder construction, the required tensioning machine comprises an oil pump, Jack, 0.25 shock oil pressure gauge of raw materials by 1 * 7-15.2-1860M
3、P a low relaxation steel strand. According to the process of construction of prestressed construction technology, pull rod, hole cleaning, steel making, steel strand transfer beam. Pre stress according to the pre tension, initial tension and final tension in three stages, the tension before the thre
4、e control: the beam of concrete reaches 35.5MPa, can be pre tensioned; strength to meet the design requirements of the 43.5MPa, can be the beginning of tension, according to the site, pre and early tension can be carried out at the same time, and, at the beginning of a pre Lajun die tensioned, the t
5、ension before the end of the beam; reached 53.5MPa in concrete strength, elastic modulus reached 35.5GPa, age greater than 10 days for the final tension; tension process, prestress value of oil pressure data, elongation value as a supplement, and to achieve three concentric, two synchronization. Pre
6、stressed equipment to do: Periodic verification (jack used more than 1 months or 200 times), periodic calibration (pressure gauge by collision or oil leakage, oil table pointer cannot be returned to zero) and before the review before the tension, determined (oil pressure gauge and Jack is correct, t
7、he empty; Jack pull 2-3, sure Jack and hydraulic pipe work) to ensure the construction process, the equipment can work normally. Tension, good protection, set up warning signs and warning line in the beam tension on both sides. In the tension after the end market to do.1. project overviewProject nam
8、e Xinxiang East Meng Jiangnu River Bridge (DK600+908.36 DK618+309.20); section name: new Shijiazhuang to Wuhan railway passenger line (Henan section). Beam field precast beams 32m, 24 m, post tensioned prestressed concrete box girder. 32M beam span length 32.6m, 31.5m; 24m beam length 24.6m, span 23
9、.5m. Box girder type single chamber single box box girder, girder concrete strength design for C50 grade, prestressed steel is a high strength low relaxation steel strand, anchorage system by self anchored system drawing, pipe formed by pulling the rubber rod into the hole.Project objectives: plans
10、in November 11, to begin construction in January 25, beam field, trial production, in May 30, the official production, April 30, to complete the entire precast box girder, the total duration of 18 months.2. tensioning machine2.1 jackJack with YD2500/200, YD3000/200 Jack Siping City Machinery Co. Ltd
11、. the production of prestressed rio. According to the tension tension value of prefabricated box girder Yuchu Zhang used YD2500/200 type jack, final tension using YD3000/200 type jack.2.2 tension pumpZB2*2/55 electric high pressure pump pump selection of Siping City Machinery Co. Ltd. the production
12、 of prestressed rio.2.3 tension oil gaugeTensioning hydraulic table selection of earthquake type, beam field with 0.25 grade earthquake type oil, oil table the maximum range is 60MPa, the minimum scale 0.2 MPa dial diameter is 150mm. Calibration once a month,Must be calibrated once a week.2.4 anchor
13、sFound that the steel wire sliding wire, broken wire clip retraction does not meet the requirements, the anchors of the whole steel strand anchors.2.5 prestressed equipment calibration2.5.1 prestressed equipment should be done: Periodic verification, calibration, check before useIn order to ensure t
14、he accuracy of the 2.5.2 tension on a regular basis, tension equipment calibration pressure and output force . Application of equipment and instrument for prestressing by hand use and management and regular maintenance and calibration. Jack and pressure gauge matching check, to determine the relatio
15、nship between tension and pressure gauge, as the basis of tension. Jack, oil table calibration before use, or not use. Jack and the supporting pressure gauge calibration, the calibration method of jacking pressure testing machine or pressure sensor, the piston is approximately equal to the amount of
16、 exposure exposure test at max load; under various load to gauge the whole dial readings corresponding to press the dial readings. Complete the calibration data for the linear regression, the regression equation is y=a+bx, linear correlation coefficient is not less than 0.9999, the check coefficient is less than 1.05, and calculated under various load values according to the loading level.2.5.3 Jack in t
