Study on the Stress State of Hollow Slab Hinged Joint Under Vehicle

Load

Houxuan Wu

, Hanbin Yi

and Jian Wang

Jiangxi Gan-Yue Expressway Corporation, Nanchang 330038, Jiangxi, China

Jiangxi transportation institute, Nanchang, Jiangxi, china

Keywords: Hollow slab, hinge joints, horizontal distribution, stress state.

Abstract: In this paper, an experimental study on the real stress state of the hinge joint is carried out for the

prefabricated hollow girder bridge. The tests were divided into three working conditions: 1) center cloth

loading, 2) symmetrical cloth loading on both sides and 3) cloth loading on one side. From the test results,

the measured transverse distribution values of the boards under three working conditions are all lower than

that of the value calculated by Hinged Plate theory, and the distribution curve is more flat. In addition, under

the three conditions, there is positive strain in the transverse direction of the concrete joints, and the strain

distribution is uneven with tensile and compressive strain coexisting along the cross-sectional height of the

joint. Judging from the bridge design theory and test results, the concrete joints of hollow slabs has the

function of internal force transmission between the slabs, and the concrete joints are under the action of

shear force and bending moment.

1 INTRODUCTION

Assembled hollow concrete beams are widely used

in China's small and medium-span bridges. The

traditional hinging slab method considers that the

hinge joints transmit only the vertical shear force,

then the internal forces of the structure can be solved

out by obtaining the transverse load distribution

coefficient of each hollow slab under the vehicle

load. The existing research literatures and bridge

experiments have proved the effectiveness of

hinging slab method in engineering design (Shao

Xudong, 2007; Guohao Li, 2007). However, both

shear and bending moment acts on the hinge joint in

practical structures, and the stress state is very

complicated

(Liu Chenguang, 2002). In recent years,

the most typical disease of the hollow slab is

cracking longitudinally of the hinge joint and its

reflection on the surface of the deck pavement (Pu

Guangning, 2008; Journal Huazhong University,

2008). Therefore, a better understanding of the

actual stress state of the hollow slab joint is a basis

for grasping its workability and structure, as well as

for obtaining a reinforcement suggestion for hollow

slab bridges with hinged joints.

Based on the calculation and analysis method for

stress state of hollow girder bridges and the

arrangement characteristics of hollow slab hinge

joints, this paper studied the corresponding

calculation model and revealed the stress state of the

hinge joints of the hollow girder bridge concrete

under vehicle load.

2 LOAD TEST OF HOLLOW

SLAB JOINT REAL BRIDGE

The test bridge is a 20 m-long new prefabricated

prestressed concrete hollow girder bridge with a

calculated span of 19.3 m and a bridge width of 13.5

m. The test bridge consists of 9 intermediate slabs

and 2 edge slabs, with a total of 10 hinge joints. The

hollow slab is 1.17 m wide and 0.9 m high (Figure

1), the main beam is composed of C40 concrete.

117

9755 55

117

50 8 32

133.5

11871

1 26.5

Figure 1 hollow plate cross-section (unit: cm)

284

Wu, H., Yi, H. and Wang, J.

Study on the Stress State of Hollow Slab Hinged Joint Under Vehicle Load.

In 3rd International Conference on Electromechanical Control Technology and Transportation (ICECTT 2018), pages 284-287

ISBN: 978-989-758-312-4

The test purpose is to observe the stress state of

the joints under the test vehicle action. The test

includes measuring the vertical displacement of each

slab using dial indicators and measuring the joints’

strain using strain gauges. Strain measuring points

located at inside or outside of hinge joints, as shown

in Figure 2. The external strain point of reaming

joints refers to the horizontal type strain gauge

installed across the joints. Because some adjacent

hollow slabs are in error, the site selection is

arranged at the joints of No. 2, No. 5, No. 6 and No.

7 cross sections. No. 6 slab center set transverse

strain measuring point. No. 6 hinge at the cross-

section stitches horizontal strain gauge. From the top

to bottom is No. 1 to No. 4 measuring points,

respectively.

Figure 2 Hollow slab joint strain measurement point

arrangement (unit: cm)

The test uses two vehicles for loading. The total

weight of No. 1 loading vehicle is 30.9 t and that of

No. 2 loading vehicle is 29.2 t. The test loading has

three conditions, loading car size and location are

shown in Figure 3.

(1) Condition 1: Two loading vehicles are

arranged at the center of the bridge, referred to as

"loading at the center";

(2) Condition 2: Two loading vehicles are

arranged along two sides of the bridge shoulder;

respectively, referred to as "loading at two sides";

(3) Condition 3: Two loading vehicles are

arranged along one side of the bridge shoulder,

referred to as "loading at one side" for short.

a) Condition 1

b) Condition 2

c) Condition 3

Figure 3 Vehicle loading conditions (unit: cm)

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3 RESULTS AND DISCUSSION

3.1 Transverse load distribution of

hollow slab

The transverse load distribution in this paper is the

ratio of the deflection of each slab span measured by

the test vehicle to the sum of the measured

deflection of each slab. The distribution of the load

is smoother along the cross-bridge, the better the

Study on the Stress State of Hollow Slab Hinged Joint Under Vehicle Load

285

structural integrity is and can indirectly reflect the

bearing performance of hollow slab hinge joints.

a) Condition 1

b) Condition 2

c) Condition 3

Figure 4 cross-section of the mid-section load transverse

distribution

It can be seen from Fig. 4 that there is not much

difference between the curve of measured values and

that of the calculated values from the hinge plate

method, but the measured transverse distribution

value is smaller than the calculated value and the

distribution curve is flat.

3.2 Strain increment of joints concrete

Horizontal strain gauges were embedded in No. 6

hinge at the cross-section, as shown in Figure 5. In

particular, it should be pointed out here that the

concrete joints between the bridge hollow slabs are

constructed strictly following the construction

procedures and have good quality after quality

inspection.

Figure 5 site buried seam strain measurement point

Under different loading conditions, the measured

results for strain increment of joints concrete are

shown in Table 1 and Table 2, the values are the

strain of joints concrete under the vehicle load, "+"

is the pull, "-" is the pressure. Figure 6 shows the

stress values at different heights of No. 6 hinge

joints.

Table 1 cross-section of the reaming measured value of

external strain/με

#2 hinge

joints

#5 hinge

joints

#6 hinge

joints

#7 hinge

joints

# 6 slab

Condition 1 - 72 90 58 5

Condition 2 -3 -48 -45 -17 -4

Condition 3 -8 -8 -13 -12 -3

Table 2 No. 6 hinge joints measured strain/με

NO.1 NO.2 NO.3 NO.4

Condition 1

-27 0 -3 4

Condition 2

15 0 1 -8

Condition 3

6 -4 1 -7

a) Condition 1 b) Condition 2 c) Condition 3

Figure 6 Distribution of strain at No. 6 hinge joint under

each working condition (Unit: με)

It can be seen from Figure 6, Table 1 and Table 2

that the normal strain exists in the transverse

direction of the concrete joint under three test

conditions, and the strain distribution is uneven

along the height of the joint, and the tensile and

compressive strain coexist. Under the condition 1,

the loading vehicle is arranged at the center position

of the bridge width. The upper part of the concrete

ICECTT 2018 - 3rd International Conference on Electromechanical Control Technology and Transportation

286

joint section is the compressive strain while the

lower part is the tensile strain. This proves that there

is a transverse bending moment acting on the

concrete joint caused by the vehicle load (The

bending moment at the lower edge is positive,

otherwise negative). On the contrary, under the

condition 2 and 3, the loading vehicles are arranged

outside of the bridge shoulder. The upper part of the

concrete joint section is tensile strain while the

lower part of the section is the compressive strain.

This proves that a transverse negative moment

actually acts on the concrete hinge joint caused by

vehicle load exists.

Under the condition 1 with loading at the center

position of the bridge width, the lower edge of each

hinge joint bear tensile stress, in particular, No. 6

joint at the center of the bridge width has maximal

tensile strain, 90 με, and the corresponding tensile

stress is 3 MPa calculated using C40 concrete, which

is enough to make the whole pouring concrete crack,

especially the concrete joints are at the bonding

between new and old concrete. As the tensile

strength of the bonding interface is far lower than

the concrete matrix, the joints bonding surface may

have been cracked.

4 CONCLUSIONS

In this paper, the field bridge load test was carried

out on the prefabricated hollow girder bridge. The

experimental results show that the hollow slab joints

are actually in the complex state of bearing bending

and shearing together, and the shear and transverse

bending moment of different joints change with the

action position of the vehicle load. In particular, the

horizontal middle hollow slab hinge joints bear

transverse positive bending moment under the

condition 1, while bear negative bending moment

when under the condition 2 and 3. The absolute

value of the edge stress is the largest irrespective of

the conditions.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the financial

support provided by Transportation Science and

Technology Project of Jiangxi Provincial [Grant

2014C0001].

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Liu Chenguang. Research on design method of transverse

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