Experimental research on bearing mechanism of perfobond rib shear connectors

doi:10.1016/j.jcsr.2013.11.020

Journal of Constructional Steel Research

Volume 95, April 2014, Pages 22-31

https://doi.org/10.1016/j.jcsr.2013.11.020 Get rights and content

Highlights

•
A novel push-out test method for perfobond rib connector was proposed.
•
Failure modes of perfobond rib connector were obtained.
•
Several influence factors were investigated.

Abstract

Push-out test is widely used to study the bearing capacity of perfobond rib shear connectors. Due to the discrepancies in both the specimen size and the test procedure adopted by different researchers, the obtained results did not coincide well with each other. On the basis of the push-out test methods by previous researches, a novel push-out test technique for perfobond rib connector was proposed. 7 different groups, totally 21 push-out test specimens, were fabricated and tested. By means of the proposed test method, load–slip relationships of the specimens were obtained and their failure modes were observed. Satisfied reproducibility of load–slip curves in each group proved the rationality of the test method proposed in this paper. According to the failure phenomenon in ultimate loading state, failure mechanism of perfobond rib shear connectors was analyzed and the analysis results indicated that brittle failure always occurs in perfobond rib connectors. Based on the test results, influence of the connector configuration on the load bearing capacity was discussed.

Introduction

Nowadays steel–concrete composite structure, with its remarkable technological and economical benefits, has been widely used in civil engineering. In steel–concrete composite structures, it is the shear connectors between concrete slab and steel girder that ensure the two parts work collaboratively to bear external loads [1], [2], [3], [4]. In steel and concrete composite bridges, headed stud is the most widely used one among all kinds of shear connectors [5], [6], [7], [8]. Notwithstanding headed stud could bring about inconvenience of construction in site to a great extent, some evidences indicate that the headed studs subjected to repeated loading may suffer from fatigue failure [9], [10].

In order to overcome the drawbacks of headed studs, Fritz Leonhardt developed a new kind of shear connector, named as perfobond rib connector [9], [11]. Perfobond rib connector refers to a piece of steel plate, on which a certain number of holes are punched. After pouring of the concrete slabs, concrete dowels could be formed in these holes. The concrete dowels could resist the shear force and also the up-lifting force between the concrete slab and the steel girder. It is very convenient to install the perfobond rib connectors on the steel components and no special welding equipment is required. Besides, shear bearing capacity of perfobond rib connector is larger than that of headed studs, i.e. bearing capacity of the perfobond rib connector with one hole is several times that of single stud shear connector. No evident fatigue problem of perfobond rib connector in engineering practices was reported so far. If transverse reinforcement is provided in the holes, the shear bearing capacity could increase significantly. Due to these merits, perfobond rib connector is a promising connector in steel–concrete composite structure.

Much attention has been paid on the structural behavior of perfobond rib connectors recently and various calculation methods for the shear bearing capacity were proposed [12], [13], [14], [15], [16], [17]. Nonetheless, some studies show that calculated results of these methods do no not agree well with experimental results and the results diverge with each other in a large degree. This is mainly caused by the discrepancy in specimen size and test methods [18], [19], [20].

To this end, in this paper, a novel push-out test method for perfobond rib connector was proposed. 7 different groups of perfobond rib connectors, totally 21 push-out test specimens, were conducted to obtain the load–slip relationships of the specimens and to verify the rationality of the proposed test method. Based on the test results, influence of the parameters of the shear connectors on the bearing capacity was discussed.

Section snippets

Conventional test methods

Nowadays, both push-out test and full-scale composite beam test are usually adopted to investigate the shear bearing capacity of shear connectors [21], [22], [23], [24], [25]. Full-scale beam test method is feasible for small composite beams used in building structure, and it is difficult to test the shear bearing capacity of perfobond rib connectors in composite bridge using this method because the sizes of the connector and the girder are very large. Therefore, push-out test results are

Load–slip relationship

Load–slip curves of all the specimens obtained in the push-out tests are shown in Fig. 7. Relative slips between the steel and concrete are the average values measured by two LVDTs.

It can be seen from the load–slip curves of the 7 groups in the entire process that the load–slip curves of the 3 specimens in each group were very close to each other, and the dispersion of the bearing capacities was smaller than that of conventional push-out test results, which further proved the rationality of the

Discussions

Due to the scatter of the test result, according to the data process procedure suggested by Eurocode 4, in this paper the values whose deviation from the mean exceeds 10% in each group were removed. The bearing capacity of one group is denoted as Q_u and the relative slip corresponding to Q_u is denoted as S_u. Bearing capacity of each specimens (Q_u,i), average bearing capacity of each group (Q_u,Ave), relative slips between the steel and concrete corresponding to the bearing capacity (S_u,i) and

Conclusions

The following conclusions can be drawn based on the investigations in this paper.

(1)
The push-out test method proposed in this paper could eliminate the influence of specimen size and friction effect on structural performance of perfobond rib connector, thus it could effectively evaluate the contributions of concrete dowel and the transverse reinforcements in the loading process of perfobond rib connectors.
(2)
The relative slip between the steel and the concrete at the point of bearing capacity is very

Acknowledgments

This research is sponsored by Key Project of Chinese National Programs for Fundamental Research and Development (973 Program, Grant No: 2013CB036303), and National Science and Technology Support Program of China (No. 2009BAG15B02). These supports are gratefully acknowledged.

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View full text

Experimental research on bearing mechanism of perfobond rib shear connectors

Highlights

Abstract

Introduction

Section snippets

Conventional test methods

Load–slip relationship

Discussions

Conclusions

Acknowledgments

J Constr Steel Res

J Constr Steel Res

Comput Struct

Eng Struct

J Constr Steel Res

J Constr Steel Res

Eng Struct

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Adv Struct Eng

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Int J Steel Struct

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Int J Steel Struct

Evaluation of the load carrying capacity of the perforated shear connector with flange heads

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Eng Struct

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J Struct Eng Asce