1. Zhejiang Provincial Institute of Communications Planning, Design and Research, Hangzhou 310006, China 2. School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China 3. School of Civil Engineering and Transportation, South China University of Technology, Guangzhou 510641, China
The anti-slip scheme of adding vertical friction plate to the saddle was investigated, in order to solve the structural design constraint of multi-pylon suspension bridge caused by slip between the main cable and the middle saddle. The corresponding test models were made to investigate the slip behavior of cable strands when equipped with vertical friction plate. Totally, four experimental cases were carried out considering the effects of the number of strands. Combined with the existing studies on the lateral force of main cable, a slip analytical model was established. A three-pylon double-deck suspension bridge that firstly adopted concrete mid-pylon, namely the Oujiang River North Estuary Bridge, was taken as a practical engineering case; and the comparison study for anti-slip design was conducted by adjusting the number of vertical friction plates. Results show that, with the continuous loading of the unbalanced force, the cable strands display layered-slipping phenomenon from top to down obviously. The friction resistance of the main cable can be enhanced effectively through adding vertical friction plate. The proposed analytical model is applicable to the anti-slip design of the main cable when the vertical friction plate is added. Setting vertical friction plates among saddle notches can provide the main cable with the relatively best anti-slip performance.
Fig.3Settings of displacement measuring area in slip test site
工况编号
ns
索股编号
设位移测点的索股
A
1
1#
1#
B
4
1#~4#
1#~4#
C
7
1#~7#
1#、3#~7#
D
10
1#~10#
1#、3#~4#、6#~10#
Tab.1Arrangement of slip test cases
Fig.4Curves for analyzing slip behavior of strand (8# strand in case D)
工况编号
滑移索股编号
μ(i)
工况A
1#
0.371
工况B
2#
0.331
4#
0.458
1#
0.486
工况C
5#
0.337
6#
0.337
4#
0.548
1#
0.591
工况D
8#
0.312
10#
0.360
6#
0.495
4#
0.618
1#
0.639
Tab.2Test results of nominal friction coefficient
Fig.5Slip analytical model of cable strands
Fig.6Comparison between calculated and measured results of test cases
Fig.7Slip conditions of cable strands of real bridge under three anti-slip schemes
方案
nv
μ
K
首滑
终滑
首滑
终滑
C1
14
0.179
0.422
1.20
2.83
C2
10
0.150
0.330
1.01
2.22
C3
6
0.150
0.283
1.01
1.90
Tab.3Calculation results of three anti-slip schemes
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