1、豎向預(yù)應(yīng)力筋預(yù)應(yīng)力損失的試驗(yàn)研究朱浩1；芶潔 2（1成都合眾橋梁科技有限公司 四川成都 610031； 2貴州交通職業(yè)技術(shù)學(xué)院 貴州貴陽(yáng) 550008）摘要：預(yù)應(yīng)力混凝土梁式橋豎向預(yù)應(yīng)力鋼筋因其長(zhǎng)度較短，即使出現(xiàn)很微小的松弛或錨頭回縮也會(huì)出現(xiàn)較大的預(yù)應(yīng)力損失，以至于危及結(jié)構(gòu)安全。因此本文主要對(duì)豎向預(yù)應(yīng)力鋼筋預(yù)應(yīng)力損失展開(kāi)研究，并為以后同類橋梁設(shè)計(jì)提供參考數(shù)據(jù)。關(guān)鍵詞：豎向 鋼筋 預(yù)應(yīng)力 預(yù)應(yīng)力損失 試驗(yàn)1. 概述橋梁結(jié)構(gòu)的豎向預(yù)應(yīng)力筋通常采用精軋螺紋鋼筋（高強(qiáng)鋼筋）。由于豎向預(yù)應(yīng)力筋通常長(zhǎng)度較短，因此精軋螺紋鋼筋即使出現(xiàn)很微小的松弛或錨頭回縮也將引起豎向預(yù)應(yīng)力筋出現(xiàn)較大的預(yù)應(yīng)力損失，以至于危及

2、結(jié)構(gòu)安全。 本次試驗(yàn)主要圍繞如何降低豎向預(yù)應(yīng)力筋的預(yù)應(yīng)力損失展開(kāi)，通過(guò)試驗(yàn)達(dá)到：（1）獲得豎向預(yù)應(yīng)力筋損失的影響因素及控制要素；（2）獲得豎向預(yù)應(yīng)力永存應(yīng)力的實(shí)測(cè)資料，為今后橋梁的病害分析及同類橋梁的設(shè)計(jì)提供第一手資料；2. 試驗(yàn)方法和設(shè)備預(yù)應(yīng)力損失分為兩部分：瞬時(shí)預(yù)應(yīng)力損失和長(zhǎng)期預(yù)應(yīng)力損失兩部分。瞬時(shí)預(yù)應(yīng)力損失主要包括錨具變形和接縫壓縮，以及混凝土支架的管道摩阻損失。長(zhǎng)期預(yù)應(yīng)力損失主要由鋼筋松弛和混凝土的收縮徐變以及溫度變化引起。對(duì)于大跨徑混凝土梁式橋豎向預(yù)應(yīng)力控制技術(shù)研究主要采用試驗(yàn)研究，通過(guò)在特別設(shè)計(jì)的試件上對(duì)預(yù)應(yīng)力筋進(jìn)行加載，測(cè)試預(yù)應(yīng)力筋中的有效預(yù)應(yīng)力隨時(shí)間的變化，通過(guò)對(duì)試驗(yàn)數(shù)據(jù)的各種

3、分析得出相應(yīng)地研究結(jié)論。本試驗(yàn)共選用3根5m長(zhǎng)的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼，編號(hào)分別是C5,C6,C7。依次在鋼支架上張拉，然后放張并連續(xù)測(cè)量10d的預(yù)應(yīng)力損失。1.1.1 回縮量對(duì)比及松弛試驗(yàn)方案利用A類試件形式，取L4000mm，選用Error! Reference source not found.中的高強(qiáng)鋼筋類型，每種類型進(jìn)行3組試驗(yàn)，在常溫環(huán)境進(jìn)行試驗(yàn)。試驗(yàn)流程為：（1）將高強(qiáng)鋼筋張拉至0.8倍屈服強(qiáng)度，記錄各傳感器讀數(shù)；（2）用手旋緊錨具，千斤頂卸壓錨固，記錄各傳感器讀數(shù)；（3）持荷10天，每隔2小時(shí)記錄各傳感器讀數(shù)。（4）分析獲得各廠家高強(qiáng)鋼筋的錨具回縮量及松弛值。為加快試驗(yàn)進(jìn)度，本

4、試驗(yàn)采用4套試件同步進(jìn)行。1.1.2 疲勞試驗(yàn)方案利用C類試件形式，取L4000mm,選用Error! Reference source not found.的高強(qiáng)鋼筋類型，每種類型進(jìn)行1組(含兩根高強(qiáng)鋼筋)試驗(yàn)，在常溫環(huán)境進(jìn)行試驗(yàn)。試驗(yàn)流程為：（1） 對(duì)試件進(jìn)行張拉，張拉噸位為0.8倍高強(qiáng)鋼筋屈服強(qiáng)度，錨固后記錄傳感器讀數(shù)；（2） 對(duì)預(yù)應(yīng)力孔道進(jìn)行壓漿，并每隔24h記錄傳感器讀數(shù)；（3） 壓漿材料強(qiáng)度滿足要求后利用MTS試驗(yàn)機(jī)對(duì)試件進(jìn)行疲勞加載，傳感器采樣周期為1h，根據(jù)計(jì)算分析確定加載噸位及加載循環(huán)次數(shù)。（4） 分析獲得各廠家高強(qiáng)鋼筋的永存應(yīng)力和加載次數(shù)的關(guān)系。1.1.3 錨固區(qū)混凝土影響

5、試驗(yàn)方案利用B類試件形式，取L4000mm，選用國(guó)產(chǎn)32高強(qiáng)精軋螺紋鋼，試件數(shù)量為3組，同時(shí)利用Error! Reference source not found.中的A類試件進(jìn)行對(duì)比試驗(yàn)，在常溫環(huán)境進(jìn)行試驗(yàn)。試驗(yàn)流程為：（1）將高強(qiáng)鋼筋張拉至0.8倍屈服強(qiáng)度，記錄各傳感器讀數(shù)；（2）用手旋緊錨具，千斤頂卸壓錨固，記錄各傳感器讀數(shù)；（3）持荷10天，每隔12小時(shí)記錄各傳感器讀數(shù)。（4）分析獲得錨固區(qū)混凝土對(duì)高強(qiáng)鋼筋錨固效果的影響。（5）另外，從對(duì)比A類構(gòu)件的結(jié)果可以得到10天的松弛結(jié)果。試驗(yàn)方法：第節(jié)、第節(jié)、第節(jié)；試驗(yàn)設(shè)備： 第5.2節(jié) 。3、將和8.4節(jié)的內(nèi)容合并成文章的主體。將1.1.4

6、國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼松弛回縮試驗(yàn)該組實(shí)驗(yàn)一共選了3根表 1.21 國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼C5預(yù)應(yīng)力損失（單位：KN）C5總損失時(shí)間效應(yīng)損失二次張拉600600.617回油穩(wěn)定575.85324.7641h574.42826.1891.4262h573.80826.8092.0463h572.9427.6772.9134h572.50628.1113.3475h572.19628.4213.6576h571.79328.8244.067h571.728.9174.1538h571.4929.1274.3639h571.28529.3324.56810h571.08829.5294.76511h570.

7、89129.7264.96212h570.69429.9235.15913h570.49930.1185.35414h570.30930.3085.54415h570.27530.3425.57916h569.961 30.656 5.892 17h568.748 31.869 7.105 18h567.846 32.771 8.007 19h566.478 34.139 9.375 20h564.798 35.819 11.055 22h564.923 35.694 10.930 24h563.959 36.658 11.894 26h561.937 38.680 13.916 28h561

8、.657 38.960 14.196 40h561.595 39.022 14.258 46h561.004 39.613 14.849 52h559.884 40.733 15.969 64h559.293 41.324 16.560 70h557.458 43.159 18.395 76h557.303 43.314 18.550 88h557.707 42.910 18.146 96h555.250 45.367 20.603 102h555.343 45.274 20.510 114h555.592 45.025 20.261 120h553.508 47.109 22.345 126

9、h554.037 46.580 21.816 138h554.472 46.145 21.381 144h551.766 48.851 24.087 150h552.637 47.980 23.216 162h553.570 47.047 22.283 168h551.424 49.193 24.429 174h552.450 48.167 23.403 186h552.077 48.540 23.776 192h550.615 50.002 25.238 198h551.424 49.193 24.429 210h550.895 49.722 24.958 216h550.087 50.53

10、0 25.766 222h550.824 49.793 25.029 234h550.095 50.522 25.758 240h549.487 51.130 26.366 表 1.22 32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼C6預(yù)應(yīng)力損失（單位：KN）C6總損失時(shí)間效應(yīng)損失二次張拉600603.875回油穩(wěn)定560.04743.8281h559.12944.7460.9192h558.57745.2981.473h557.90445.9722.1444h557.50546.372.5425h557.19946.6762.8486h556.92346.9523.1247h556.7447.1353.3088h

11、556.55647.3193.4929h556.37547.53.67310h556.20247.6733.84611h556.0347.8454.01812h555.86348.0124.18513h555.70348.1724.34514h555.60348.2724.44515h555.57648.2994.47216h555.155 48.720 4.892 17h553.942 49.933 6.105 18h553.040 50.835 7.007 19h551.672 52.203 8.375 20h549.992 53.883 10.055 22h550.117 53.758

12、9.930 24h549.153 54.722 10.894 26h547.131 56.744 12.916 28h546.851 57.024 13.196 40h546.789 57.086 13.258 46h546.198 57.677 13.849 52h545.078 58.797 14.969 64h544.487 59.388 15.560 70h542.652 61.223 17.395 76h542.497 61.378 17.550 88h542.901 60.974 17.146 96h540.444 63.431 19.603 102h540.537 63.338

13、19.510 114h540.786 63.089 19.261 120h538.702 65.173 21.345 126h539.231 64.644 20.816 138h539.666 64.209 20.381 144h536.960 66.915 23.087 150h537.831 66.044 22.216 162h538.764 65.111 21.283 168h536.618 67.257 23.429 174h537.644 66.231 22.403 186h537.271 66.604 22.776 192h535.809 68.066 24.238 198h536

14、.618 67.257 23.429 210h536.089 67.786 23.958 216h535.281 68.594 24.766 222h536.018 67.857 24.029 234h535.289 68.586 24.758 240h534.681 69.194 25.366 表 1.23 32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼C7預(yù)應(yīng)力損失（單位：KN）C7總損失時(shí)間效應(yīng)損失二次張拉600602.999 回油穩(wěn)定569.744 33.255 1h567.843 35.156 1.901 2h567.322 35.677 2.422 3h566.955 36.044 2.789 4h566

15、.525 36.474 3.219 5h566.525 36.474 3.219 6h566.206 36.793 3.538 7h565.915 37.084 3.829 8h565.664 37.335 4.080 9h565.444 37.555 4.300 10h565.250 37.749 4.494 11h565.059 37.940 4.685 12h564.867 38.132 4.877 13h564.748 38.251 4.996 14h564.588 38.411 5.156 15h564.468 38.531 5.276 16h564.152 38.847 5.592

16、 17h562.939 40.060 6.805 18h562.037 40.962 7.707 19h560.669 42.330 9.075 20h558.989 44.010 10.755 22h559.114 43.885 10.630 24h558.150 44.849 11.594 26h556.128 46.871 13.616 28h555.848 47.151 13.896 40h555.786 47.213 13.958 46h555.195 47.804 14.549 52h554.075 48.924 15.669 64h553.484 49.515 16.260 70

17、h551.649 51.350 18.095 76h551.494 51.505 18.250 88h551.898 51.101 17.846 96h549.441 53.558 20.303 102h549.534 53.465 20.210 114h549.783 53.216 19.961 120h547.699 55.300 22.045 126h548.228 54.771 21.516 138h548.663 54.336 21.081 144h545.957 57.042 23.787 150h546.828 56.171 22.916 162h547.761 55.238 2

18、1.983 168h545.615 57.384 24.129 174h546.641 56.358 23.103 186h546.268 56.731 23.476 192h544.806 58.193 24.938 198h545.615 57.384 24.129 210h545.086 57.913 24.658 216h544.278 58.721 25.466 222h545.015 57.984 24.729 234h544.286 58.713 25.458 240h543.678 59.321 26.066 圖 1.21 國(guó)產(chǎn)高強(qiáng)鋼筋松弛引起的預(yù)應(yīng)力損失將預(yù)應(yīng)力筋總的預(yù)應(yīng)力損

19、失分為瞬時(shí)損失和長(zhǎng)期損失，下面將分別分析這兩種預(yù)應(yīng)力損失。 根據(jù)公路鋼筋混凝土及預(yù)應(yīng)力混凝土橋涵設(shè)計(jì)規(guī)范（JTG D62-2004）（以下簡(jiǎn)稱規(guī)范）中表的規(guī)定，錨具變形和接縫壓縮按照1mm計(jì)算，則這兩項(xiàng)引起的鋼筋預(yù)應(yīng)力損失為38.5kN。而根據(jù)試驗(yàn)結(jié)果，三根32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的瞬時(shí)預(yù)應(yīng)力損失分別為24 kN、43kN和33 kN，平均值為33 kN，在規(guī)范規(guī)定的范圍內(nèi)；而最大值43kN，比按規(guī)范得出的計(jì)算值略大。長(zhǎng)期預(yù)應(yīng)力損失主要由鋼筋松弛引起。根據(jù)規(guī)范中的規(guī)定，采用超張拉的精軋螺紋鋼筋，由于鋼筋松弛引起的預(yù)應(yīng)力損失極值按照0.035倍的張拉應(yīng)力計(jì)算。根據(jù)規(guī)范中F.3的規(guī)定，鋼筋松弛引起的

20、10d預(yù)應(yīng)力損失值按照0.61倍的損失極值計(jì)算，則鋼支架上的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的10d的預(yù)應(yīng)力損失的理論值為13kN。根據(jù)試驗(yàn)結(jié)果，三根32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的10d的平均預(yù)應(yīng)力損失為26kN，這與規(guī)范規(guī)定的理論值相比大約超出了13kN。假設(shè)施工操作不規(guī)范，沒(méi)有到達(dá)規(guī)范對(duì)于超張拉的要求，改為按照一次張拉計(jì)算，松弛引起的預(yù)應(yīng)力損失極值為0.05倍的張拉應(yīng)力，則32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的10d的預(yù)應(yīng)力損失的理論值為18.3kN，與實(shí)測(cè)值相比仍小8kN左右。1.2 混凝土對(duì)錨固效果的影響試驗(yàn)本組試驗(yàn)將分別對(duì)一組5m長(zhǎng)32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼和一組9m長(zhǎng)32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼進(jìn)行張拉，然后放張并連續(xù)觀

21、測(cè)10d，試驗(yàn)的目的是通過(guò)對(duì)比混凝土支架和鋼支架上鋼筋的預(yù)應(yīng)力損失，獲得錨固區(qū)混凝土對(duì)高強(qiáng)鋼筋錨固效果的影響。 圖 1.21 混凝土支架與鋼支架對(duì)比試驗(yàn)1.2.1 5m國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼對(duì)比試驗(yàn)該組實(shí)驗(yàn)一共選了4根5m長(zhǎng)的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼，編號(hào)分別是C7,C8,C9,C10，其中C7在鋼支架上張拉，其余3根在混凝土支架上張拉。表 1.21 鋼支架預(yù)應(yīng)力長(zhǎng)期損失（鋼筋C7長(zhǎng)5m）C7（鋼支架）溫度總損失時(shí)間效應(yīng)損失二次張拉600605.435 14.0 回油穩(wěn)定577.628 14.0 27.806 1h576.384 13.5 29.050 1.244 2h575.233 13.0 30

22、.201 2.395 3h574.922 13.0 30.512 2.706 4h574.269 13.0 31.165 3.359 5h573.927 13.0 31.507 3.701 6h573.678 13.0 31.756 3.950 7h573.274 13.0 32.161 4.354 8h572.994 12.5 32.441 4.634 9h572.745 12.5 32.689 4.883 10h572.621 12.5 32.814 5.008 11h572.434 12.5 33.000 5.194 12h572.434 12.5 33.000 5.194 13h572

23、.310 12.5 33.125 5.319 14h572.154 13.0 33.280 5.474 15h572.061 13.0 33.374 5.567 16h570.537 16.0 34.898 7.092 17h569.324 13.5 36.111 8.305 18h568.422 13.0 37.013 9.207 19h567.053 20.0 38.381 10.575 20h565.374 16.5 40.061 12.255 22h565.498 15.5 39.936 12.130 24h564.534 19.0 40.901 13.094 26h562.512 1

24、8.5 42.922 15.116 28h562.232 16.5 43.202 15.396 40h562.170 22.0 43.264 15.458 46h561.579 20.0 43.855 16.049 52h560.459 18.0 44.975 17.169 64h559.868 22.0 45.566 17.760 70h558.033 21.0 47.401 19.595 76h557.878 19.0 47.557 19.750 88h558.282 24.0 47.152 19.346 96h555.825 22.0 49.609 21.803 102h555.918

25、20.0 49.516 21.710 114h556.167 24.0 49.267 21.461 120h554.083 22.5 51.351 23.545 126h554.612 21.0 50.822 23.016 138h555.048 24.0 50.387 22.581 144h552.342 24.0 53.093 25.287 150h553.212 19.0 52.222 24.416 162h554.146 22.0 51.289 23.483 168h551.999 21.0 53.435 25.629 174h553.026 19.0 52.409 24.603 18

26、6h552.653 24.0 52.782 24.976 192h551.191 23.0 54.244 26.438 198h551.999 20.0 53.435 25.629 210h551.471 26.0 53.964 26.158 216h550.662 24.0 54.773 26.966 222h551.399 19.0 54.035 26.229 234h550.671 24.0 54.764 26.958 240h550.062 23.0 55.373 27.566 表 1.22 混凝土支架預(yù)應(yīng)力長(zhǎng)期損失（鋼筋C8長(zhǎng)5m）C8（混凝土支架）溫度總損失時(shí)間效應(yīng)損失二次張拉60

27、0609.808 13.5 回油穩(wěn)定593.539 13.5 16.270 1h591.745 13.0 18.063 1.794 2h590.958 13.0 18.850 2.580 3h590.234 13.0 19.574 3.304 4h589.637 13.0 20.172 3.902 5h588.850 13.0 20.959 4.689 6h588.472 13.5 21.336 5.067 7h588.126 13.5 21.682 5.413 8h587.623 13.0 22.186 5.916 9h587.276 13.0 22.532 6.262 10h586.804

28、 13.0 23.004 6.734 11h586.521 13.0 23.287 7.018 12h586.143 13.0 23.665 7.395 13h585.892 13.0 23.917 7.647 14h585.514 12.5 24.294 8.025 15h585.420 12.5 24.389 8.119 16h585.199 12.5 24.609 8.339 17h585.042 12.5 24.766 8.497 18h584.916 12.5 24.892 8.623 19h584.979 12.5 24.829 8.560 20h584.948 13.0 24.8

29、61 8.591 22h585.073 13.0 24.735 8.465 24h584.224 16.0 25.585 9.315 26h581.580 13.5 28.228 11.958 28h579.629 13.0 30.179 13.909 40h580.605 20.0 29.204 12.934 46h577.804 16.5 32.004 15.735 52h576.042 15.5 33.767 17.497 64h577.301 19.0 32.508 16.238 70h574.217 18.5 35.592 19.322 76h572.454 16.5 37.354

30、21.084 88h573.996 22.0 35.812 19.542 96h571.196 20.0 38.613 22.343 102h569.056 18.0 40.753 24.483 114h570.503 22.0 39.305 23.036 120h567.797 21.0 42.012 25.742 126h565.783 19.0 44.026 27.756 138h567.797 24.0 42.012 25.742 144h564.587 22.0 45.221 28.952 150h562.856 20.0 46.952 30.683 162h564.461 24.0

31、 45.347 29.078 168h561.786 22.5 48.022 31.753 174h560.055 21.0 49.753 33.483 186h562.227 24.0 47.582 31.312 192h559.206 24.0 50.603 34.333 198h558.545 19.0 51.263 34.994 210h560.307 22.0 49.501 33.232 216h557.538 21.0 52.271 36.001 222h556.594 19.0 53.215 36.945 234h559.930 24.0 49.879 33.609 240h55

32、6.908 23.0 52.900 36.630 表 1.23 混凝土支架預(yù)應(yīng)力長(zhǎng)期損失（鋼筋C9長(zhǎng)5m）C9（混凝土支架）溫度總損失時(shí)間效應(yīng)損失二次張拉600609.667 14.0 回油穩(wěn)定584.315 13.0 25.353 1h580.193 13.0 29.475 4.122 2h578.209 13.0 31.458 6.106 3h576.877 13.0 32.791 7.438 4h575.296 13.0 34.372 9.019 5h574.645 13.5 35.022 9.670 6h574.025 13.5 35.642 10.290 7h573.219 13.0

33、 36.448 11.096 8h572.630 13.0 37.037 11.684 9h572.104 13.0 37.564 12.211 10h571.670 13.0 37.998 12.645 11h571.174 13.0 38.494 13.141 12h570.802 13.0 38.866 13.513 13h570.461 12.5 39.207 13.854 14h570.151 12.5 39.516 14.164 15h569.872 12.5 39.795 14.443 16h569.624 12.5 40.043 14.691 17h569.500 12.5 4

34、0.167 14.815 18h569.438 12.5 40.229 14.877 19h569.283 13.0 40.384 15.032 20h569.128 13.0 40.539 15.187 22h567.765 16.0 41.903 16.550 24h565.037 13.5 44.630 19.278 26h563.054 13.0 46.614 21.261 28h563.333 20.0 46.335 20.982 40h560.543 16.5 49.124 23.772 46h559.055 15.5 50.612 25.260 52h559.737 19.0 4

35、9.930 24.578 64h556.886 18.5 52.782 27.429 70h555.460 16.5 54.207 28.855 76h556.576 22.0 53.092 27.739 88h554.189 20.0 55.478 30.125 96h552.423 18.0 57.245 31.892 102h553.167 22.0 56.501 31.148 114h550.749 21.0 58.918 33.566 120h549.200 19.0 60.468 35.115 126h550.966 24.0 58.701 33.349 138h547.371 2

36、2.0 62.297 36.944 144h546.472 20.0 63.195 37.843 150h547.960 24.0 61.708 36.355 162h544.799 22.5 64.869 39.516 168h543.466 21.0 66.202 40.849 174h545.418 24.0 64.249 38.897 186h542.536 24.0 67.131 41.779 192h542.102 19.0 67.565 42.213 198h543.869 22.0 65.799 40.446 210h540.924 21.0 68.743 43.391 216

37、h540.397 19.0 69.270 43.918 222h543.745 24.0 65.923 40.570 234h540.119 23.0 69.549 44.196 240h539.127 20.0 70.541 45.188 表 1.24 混凝土支架預(yù)應(yīng)力長(zhǎng)期損失（鋼筋C10長(zhǎng)5m）C10（混凝土支架）溫度總損失時(shí)間效應(yīng)損失二次張拉600610.721 14.0 回油穩(wěn)定575.730 14.0 34.991 1h572.135 13.0 38.587 3.595 2h570.616 13.0 40.105 5.114 3h569.066 13.0 41.655 6.664 4

38、h568.477 13.5 42.244 7.252 5h567.982 13.5 42.740 7.748 6h567.207 13.0 43.515 8.523 7h566.742 13.0 43.979 8.988 8h566.277 13.0 44.444 9.453 9h565.843 13.0 44.878 9.887 10h565.409 13.0 45.312 10.321 11h565.161 13.0 45.560 10.569 12h564.851 12.5 45.870 10.879 13h564.634 12.5 46.087 11.096 14h564.417 12

39、.5 46.304 11.313 15h564.262 12.5 46.459 11.468 16h564.169 12.5 46.552 11.561 17h564.293 12.5 46.428 11.437 18h564.293 13.0 46.428 11.437 19h564.386 13.0 46.335 11.344 20h563.271 16.0 47.451 12.459 22h560.264 13.5 50.457 15.466 24h558.622 13.0 52.100 17.108 26h559.861 20.0 50.860 15.869 28h556.514 16

40、.5 54.207 19.216 40h555.274 15.5 55.447 20.456 46h556.607 19.0 54.114 19.123 52h553.260 18.5 57.462 22.470 64h552.051 16.5 58.670 23.679 70h553.756 22.0 56.966 21.974 76h550.780 20.0 59.941 24.950 88h549.169 18.0 61.553 26.561 96h550.532 22.0 60.189 25.198 102h547.681 21.0 63.040 28.049 114h546.286

41、19.0 64.435 29.444 120h548.642 24.0 62.080 27.088 126h544.582 22.0 66.140 31.148 138h543.590 20.0 67.131 32.140 144h545.697 24.0 65.024 30.033 150h542.040 22.5 68.681 33.690 162h540.924 21.0 69.797 34.805 168h543.311 24.0 67.410 32.419 174h539.871 24.0 70.851 35.859 186h539.809 19.0 70.913 35.921 19

42、2h541.792 22.0 68.929 33.938 198h538.383 21.0 72.338 37.347 210h537.794 19.0 72.927 37.936 216h541.947 24.0 68.774 33.783 222h537.887 23.0 72.834 37.843 234h536.616 20.0 74.105 39.114 240h536.523 24.0 74.198 39.207 圖 1.22 混凝土支架上三根鋼筋(5m)的長(zhǎng)期預(yù)應(yīng)力損失曲線圖 1.23 混凝土支架與鋼支架上鋼筋(5m)的長(zhǎng)期預(yù)應(yīng)力損失對(duì)比通過(guò)前面的研究可知，總的預(yù)應(yīng)力損失分為瞬時(shí)

43、損失和長(zhǎng)期損失。下面將分別分析這兩種預(yù)應(yīng)力損失，并對(duì)比鋼支架和混凝土支架上鋼筋長(zhǎng)期預(yù)應(yīng)力損失的區(qū)別。根據(jù)規(guī)范，錨具變形和接縫壓縮按照1mm計(jì)算，引起的鋼筋預(yù)應(yīng)力損失為38.5kN?；炷林Ъ艿墓艿滥ψ钃p失為3.5kN。所以混凝土支架的瞬時(shí)預(yù)應(yīng)力損失的理論值應(yīng)為42kN，鋼支架的瞬時(shí)預(yù)應(yīng)力損失的理論值為38.5kN。根據(jù)試驗(yàn)結(jié)果，混凝土支架上的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的瞬時(shí)預(yù)應(yīng)力損失分別為16 kN、26 kN和36 kN，其中最大值36 kN，在規(guī)范規(guī)定的42kN以內(nèi)；鋼支架上的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的瞬時(shí)預(yù)應(yīng)力損失為28kN，也在規(guī)范規(guī)定的38.5kN以內(nèi)。長(zhǎng)期預(yù)應(yīng)力損失主要由鋼筋松弛和混凝土

44、的收縮徐變以及溫度變化引起。根據(jù)規(guī)范，松弛引起的預(yù)應(yīng)力損失極值按照0.05倍的張拉應(yīng)力計(jì)算，松弛引起的10d預(yù)應(yīng)力損失值按照0.61倍的損失極值計(jì)算，則鋼支架上的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的10d的預(yù)應(yīng)力損失的理論值為18.3kN。而對(duì)于混凝土支架來(lái)說(shuō)，還要考慮收縮徐變和溫度引起的預(yù)應(yīng)力損失：10d內(nèi)收縮徐變引起的預(yù)應(yīng)力損失為6kN，溫度升高了約10度，引起的預(yù)應(yīng)力損失為4.5kN，則混凝土支架上的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的10d的預(yù)應(yīng)力損失的理論值為28.8kN。根據(jù)試驗(yàn)結(jié)果，混凝土支架上的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的10d的平均預(yù)應(yīng)力損失為39kN；鋼支架上的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的10d的預(yù)應(yīng)力損

45、失為27.5kN。兩者的差值為11.5 kN,這與理論計(jì)算得出的10.5 kN（收縮徐變與溫度變化之和）是一致的，這說(shuō)明扣去收縮徐變與溫度變化的影響，混凝土支架和鋼支架上的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼的10d的預(yù)應(yīng)力損失是一致的，均為28kN左右。但是，預(yù)應(yīng)力長(zhǎng)期損失的實(shí)測(cè)值與規(guī)范規(guī)定的理論值相比大約超出了10kN。實(shí)測(cè)值（28kN）與規(guī)范規(guī)定的40d松弛引起的預(yù)應(yīng)力損失終值（30kN）的比為91%，大約相當(dāng)于34d時(shí)由于松弛引起的預(yù)應(yīng)力損失值。1.2.2 9m國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼對(duì)比試驗(yàn)該組實(shí)驗(yàn)一共選了4根9m長(zhǎng)的32國(guó)產(chǎn)高強(qiáng)精軋螺紋鋼，編號(hào)分別是C3,C11,C12,C13，其中C3在鋼支架上張拉

46、，其余3根在混凝土支架上張拉。表 1.25 鋼支架預(yù)應(yīng)力長(zhǎng)期損失（鋼筋C3長(zhǎng)9m）C3溫度總損失時(shí)間效應(yīng)損失二次張拉600605.329 13.5 回油穩(wěn)定592.517 13.5 12.813 1h590.241 13.0 15.088 2.276 2h588.694 13.0 16.636 3.823 3h587.270 13.0 18.059 5.247 4h586.466 13.0 18.864 6.051 5h585.754 13.0 19.576 6.763 6h585.042 13.0 20.287 7.475 7h584.392 12.5 20.937 8.125 8h583.

47、866 12.5 21.463 8.651 9h583.525 12.5 21.804 8.991 10h583.185 12.5 22.144 9.332 11h582.845 12.5 22.485 9.672 12h582.845 12.5 22.485 9.672 13h582.226 13.0 23.104 10.291 14h581.792 13.0 23.537 10.724 15h580.528 16.0 24.801 11.989 16h579.507 13.5 25.822 13.010 17h578.919 13.0 26.410 13.598 18h576.536 20.0 28.793 15.981 19h575.422 16.5 29.907 17