Abstract
To study the ultimate bearing capacity of Concrete-Filled Steel Tube (CFST) K-joints, theoretical analysis and numerical simulation methods were adopted. A finite element model of a K-joint was established and verified with test data. Based on this model, the failure modes of the K-joint were studied. The results showed that the load-displacement curves of CFST K-joints can be divided into three stages: an elastic stage, an elastic-plastic stage and a failure stage. There were two types of failure modes for K-joints: local buckling failure at the connection between a branch pipe and the main pipe due to compression and tearing failure at the connection between a branch pipe and the main pipe due to tensile forces. The factors that influence the ultimate bearing capacity of CFST K-joints were studied, and the results were as follows. The ultimate bearing capacity increased as the radius-thickness ratio of the main pipe, radius-thickness ratio of the branch pipes and gap between branch pipes decreased. Additionally, the ultimate bearing capacity of the CFST K-joints increased with increasing core concrete grade, outer diameter ratio and thickness ratio between the branch pipe and main pipe. As the angle between the axis of the branch pipe and the axis of the main pipe increased, the ultimate bearing capacity initially decreased and then increased. As the axial pressure level in the main pipe increased, the ultimate bearing capacity of the K-joint initially increased and then decreased. A positive linear correlation was observed between the growth coefficient of the ultimate bearing capacity and the scaling factor. Moreover, the ultimate bearing capacity of CFST K-joints can be significantly improved by using core concrete. Finally, formulas for the ultimate bearing capacity of K-joints under different failure modes were proposed, and the results provide a reference for the design of CFST arch bridges.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Cai, S. H. and Jiao, Z. S. (1984). “Behavior and ultimate strength of short concrete–filled steel tubular columns.” Journal of Building Structures, no. 6, pp. 13–29.
Chen, B. C. and Huang, W. J. (2007). “Experimental research on ultimate load carrying capacity of truss girders made with circular tubes.” Journal of Building Structures, vol. 28, no. 3, pp. 31–36, DOI: 10.14006/j.jzjgxb.2007.03.005.
Chen, B. C. and Huang, W. J. (2009). “Experimental study on ultimate bearing capacity of CFST directly–welded K–joints.” China Civil Engineering Journal, vol. 42, no. 12, pp. 91–98, DOI: 10.15951/j.tmgcxb.2009.12.017.
Chen, J., Sun, W. J., and Nie, J. G. (2017a). “Study on spatial effect of concrete–filled steel tubular KK–joints.” Journal of Building Structures, Vol. 38, No. S1, pp. 402–408, DOI: 10.14006/j.jzjgxb.2017.S1.056.
Chen, B. C., Wei, J. G., Zhou, J., and Liu, J. P. (2017b). “Application of concrete–filled steel tube arch bridges in China: Current status and prospects.” China Civil Engineering Journal, vol. 50, no. 6, pp. 50–61, DOI: 10.15951/j.tmgcxb.2017.06.006.
Han, L. H. (1997). “Theoretical analysis and experimental researches for the behaviors of high strength concrete filled steel tubes subjected to axial compression.” Industrial Construction, vol. 27, no. 11, pp. 39–44, DOI: 10.13204/j.gyjz1997.11.010.
Hou, C. and Han, L. H. (2017). “Analytical behavior of CFDST chord to CHS brace composite K–joints.” Journal of Constructional Steel Research, vol. 128, no. 2017, pp. 618–632, DOI: 10.1016/j.jcsr. 2016.09.027.
Hou, C., Han, L. H., and Mu, T. M. (2017). “Behaviors of CFDST chord to CHS brace composite K–joints: Experiments.” Journal of Constructional Steel Research, vol. 135, no. 2017, pp. 97–109, DOI: 10.1016/j.jcsr.2017.04.015.
Huang, W. J. and Chen, B. C. (2006). “Experimental research on concrete filled steel tube truss girder under bending.” Journal of Architecture and Civil Engineering, vol. 23, no. 1, pp. 29–33, DOI: 10.3321/j.issn:1673–2049.2006.01.005.
Huang, W. J., Fenu, L., Chen, B. C., and Briseghella, B. (2015). “Experimental study on K–joints of concrete–filled steel tubular truss structures.” Journal of Constructional Steel Research, vol. 107, pp. 182–193, DOI: 10.1016/j.jcsr.2015.01.023.
Packer, J. A. (1995). “Concrete–filled HSS connections.” Journal of Structural Engineering, vol. 121, no. 3, pp. 458–467, DOI: 10.1061/(ASCE)0733–9445(1995)121:3(458).
Sakai. Y., Hosaka, T., Isoe, T., Ichikawa, A., and Mitsuki, K. (2004). “Experiments on concrete filled and reinforced tubular K–joints of truss girder.” Journal of Constructional Steel Research, vol. 60, Nos. 3–5, pp. 683–699, DOI: 10.1016/S0143–974X(03)00136–6.
Wang, J. F., Deng, Q., and Xing, W. B. (2018). “Calculation method of the ultimate bearing capacity for circular CFST Truss K–joints.” Progress in Steel Building Structures, vol. 20, no. 2, pp. 44–52, DOI: 10.13969/j.cnki.cn31–1893.2018.02.006.
Zheng, L. Q. (2011). “Mechanical property analysis of concrete–filled circular steel tubular K–joints of truss.” Steel Construction, vol. 26, no. 11, pp. 20–23, DOI: 10.3969/j.issn.1007–9963.2011.11.005.
Zheng, J. L. (2016). “New development technology of large–span reinforced concrete arch bridges in China.” Journal of Chongqing Jiaotong University (Natural Science), Vol. 35, No. S1, pp. 8–11, DOI: 10.3969/j.issn.1674–0696.2016.sup1.02.
Zheng, J. L., Wang, J. J., Mou, T. M., Feng, Z., Han, Y., and Qin, D. Y. (2014). “Feasibility study on design and construction of concrete filled steel tubular arch bridge with a span of 700 m.” Engineering Sciences, vol. 16, no. 8, pp. 33–37, DOI: 10.3969/j.issn.1009–1742.2014.08.004.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Xie, K., Wang, H., Pang, J. et al. Study of the Ultimate Bearing Capacity of Concrete-filled Steel Tube K-Joints. KSCE J Civ Eng 23, 2254–2262 (2019). https://doi.org/10.1007/s12205-019-1268-7
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12205-019-1268-7