A Review of Shear Connectors for Glulam–Ultra-High Performance Concrete Composite Beams

YiTian Han

doi:10.63313/AERpc.9122

Authors

YiTian Han College of Civil Engineering, Central South University of Forestry and Technology, Changsha, China Author

DOI:

https://doi.org/10.63313/AERpc.9122

Keywords:

Glued laminated timber (glulam), Ultra high Performance Concrete (UHPC), Timber–Concrete Composite (TCC) Beams, Shear Connectors, Slip Modulus, Ductility, Epoxy resin anchorage, Notched connections

Abstract

Timber–concrete composite (TCC) beams combine the lightweight high strength-to-weight ratio of timber with the favourable compressive behaviour of concrete, and have been widely used in bridges and buildings. However, conventional concrete slabs suffer from large self-weight, significant creep, and pronounced cracking, which restrict the spanning capacity and durability of the composite system. Glued laminated timber (glulam) is an engineered wood product with excellent strength and dimensional stability, while ultra‑high performance concrete (UHPC) offers ultra‑high strength, high elastic modulus, and extremely low creep. The combination of glulam and UHPC to form glulam–UHPC composite (GUCC) structures is expected to overcome the performance bottlenecks of traditional TCC. The key to realising this advantage lies in the rational design of the shear connectors. This paper systematically reviews the development history and mechanical properties of shear connectors for TCC and GUCC systems, with emphasis on typical types including dowel‑type connectors, notched connections, steel plate connectors, adhesively bonded connections, and hybrid connections. The load‑carrying capacity, slip modulus, and failure modes of these connectors are analysed, and the influences of anchorage method, inclination angle of rebar, notch geometry, fibre reinforcement, and interface conditions on connection performance are summarised. Research indicates that inclined crossed arrangements, the synergistic use of notches with metallic fasteners, and epoxy‑assisted anchorage can significantly improve initial stiffness and ductility. However, purely adhesive connections exhibit brittle failure, while purely mechanical connections are limited by local crushing of timber. The introduction of UHPC shifts the failure mode of connectors from concrete crushing to steel shear or timber shear, and the slip modulus can be increased by about 18%–30%. Current research has moved from conceptual validation towards quantitative design, but further investigations are still needed on high‑stiffness‑high‑ductility hybrid connection configurations tailored for GUCC, long‑term performance evolution, and standardised test methods. Based on the identified research gaps, this paper proposes a novel hybrid connection concept comprising X‑shaped rebars, epoxy resin, and glued‑in notches in glulam, aiming to provide a theoretical basis and design reference for the development of high‑performance shear connectors for GUCC structures.

References

[1] Rodrigues, J.N., Dias, A.M.P.G. and Providencia, P. (2013) Timber-Concrete Composite Bridges: State-of-the-Art Review. BioResources, 8, 6630-6649.

[2] Jiang Yuchen, Hu Xiamin. (2019) A Review of Timber-Concrete Composite Beams. Journal of Building Structures, 40(10), 149-157.

[3] Hu Xiamin, Li Qiao, Lu Weidong, et al. (2013) Static Experimental Study on Timber-Concrete Composite Beams. Journal of Building Structures, 34(S1), 371-376.

[4] Yeoh, D., Fragiacomo, M., De Franceschi, M., et al. (2011) State of the Art on Timber-Concrete Composite Structures: Literature Review. Journal of Structural Engineering, 137, 1085-1095.

[5] Martins, C., Santos, P., Almeida, P., et al. (2015) Acoustic Performance of Timber and Timber-Concrete Floors. Construction and Building Materials, 101, 684-691.

[6] Ceccotti, A. (2002) Composite Concrete-Timber Structures. Progress in Structural Engineering and Materials, 4, 264-275.

[7] Chuan, D.Y.E. (2010) Behaviour and Design of Timber-Concrete Composite Floor System. Ph.D. Thesis, University of Auckland.

[8] Jorge, L.F., Schänzlin, J., Lopes, S.M.R., et al. (2010) Time-Dependent Behaviour of Timber Lightweight Concrete Composite Floors. Engineering Structures, 32, 3966-3973.

[9] Ferrier, E., Agbossou, A. and Michel, L. (2014) Mechanical Behaviour of Ultra-High-Performance Fibrous-Concrete Wood Panels Reinforced by FRP Bars. Composites Part B: Engineering, 60, 663-672.

[10] Naud, N., Sorelli, L., Salenikovich, A., et al. (2019) Fostering GLULAM-UHPFRC Composite Structures for Multi-Storey Buildings. Engineering Structures, 188, 406-417.

[11] Zhang Bing, Cao Yang, Huang Tao, et al. (2017) Experimental Study on Flexural Behavior of Full-Scale Glulam-Lightweight Aggregate Concrete Composite Beams. Journal of Building Structures, 2017(OS1), 297-301.

[12] Lu Weidong, Yang Huifeng, Liu Weiqing, et al. (2011) Development, Application and Prospects of Glued Laminated Timber Structures. Journal of Nanjing University of Technology (Natural Science Edition), 33(5), 105-110.

[13] Lehringer, C. and Gabriel, J. (2015) Review of Recent Research Activities on One-Component PUR-Adhesives for Engineered Wood Products. In: Aicher, S., Reinhardt, H.W. and Garrecht, H., Eds., Materials and Joints in Timber Structures, Springer, Dordrecht, 123-140.

[14] Jordahl, A. (1995) Structural Glued Laminated Timber: History of Its Origins and Early Development. Journal of the Institute of Wood Science, 13, 234-240.

[15] Zhang Lei, Li Zhiguo, Wang Minjie, et al. (2011) Development Status and Prospects of Glued Laminated Timber Buildings. Low Temperature Architecture Technology, 33(12), 28-30.

[16] Zhu Jianwei. (2021) Development Status and Prospects of Glued Laminated Timber Buildings. Modern Agricultural Research, 27(8), 137-138.

[17] Jia Shuizhong, Li Ruixiong, Shi Shuo. (2023) Design Practice of Glued Laminated Timber Long-Span Spatial Structures. Building Structure, 53(1), 9-15, 120.

[18] Paul C. Gilham. (2002) Tacoma Dome—The Construction Process of a Successful Wood Multi-purpose Stadium. World Architecture, 2002(9), 80-81.

[19] Jonnalagadda, S. and Chava, S. (2023) Ultra-High-Performance Concrete (UHPC): A State-of-the-Art Review of Material Behavior, Structural Applications and Future. Electronic Journal of Structural Engineering, 23, 25-30.

[20] Cao Junhui, Zhang Yang, Shao Xudong, et al. (2025) A Review of Research on Ultra-High-Performance Concrete (UHPC) Bridges • 2024. Municipal Engineering Technology, 43(3), 1-17.

[21] Chen Peng. (2025) A Review of the Properties, Applications and Research Progress of Ultra-High-Performance Concrete. Housing, 2025(15), 71-73.

[22] Wang, H., Li, W., Liu, X., et al. (2023) Behavior of Horizontal Steel Plate + Studs Connectors in a Glulam-UHPC Composite System: Experiment and Analysis. Engineering Structures, 275, 115187.

[23] Zhou Jianting, Zhou Lu, Yang Jun, et al. (2020) A Review of Research on the Interfacial Bond Performance between UHPC and Normal Concrete. Journal of Jiangsu University (Natural Science Edition), 41(4), 373-381.

[24] Deam, B.L., Fragiacomo, M. and Buchanan, A.H. (2008) Connections for Composite Concrete Slab and LVL Flooring Systems. Materials and Structures, 41, 495-507.

[25] Miotto, J.L. and Dias, A.A. (2012) Evaluation of Perforated Steel Plates as Connection in Glulam-Concrete Composite Structures. Construction and Building Materials, 28, 216-223.

[26] Yeoh, D., Fragiacomo, M., De Franceschi, M., et al. (2011) Experimental Tests of Notched and Plate Connectors for LVL-Concrete Composite Beams. Journal of Structural Engineering, 137, 261-269.

[27] Otero-Chans, D., Estévez-Cimadevila, J., Suárez-Riestra, F., et al. (2018) Experimental Analysis of Glued-in Steel Plates Used as Shear Connectors in Timber-Concrete-Composites. Engineering Structures, 170, 1-10.

[28] Tannert, T., Endacott, B., Brunner, M., et al. (2017) Long-Term Performance of Adhesively Bonded Timber-Concrete Composites. International Journal of Adhesion and Adhesives, 72, 51-61.

[29] Tannert, T., Gerber, A. and Vallee, T. (2020) Hybrid Adhesively Bonded Timber-Concrete-Composite Floors. International Journal of Adhesion and Adhesives, 97, 102490.

[30] Lukaszewska, E., Johnsson, H. and Fragiacomo, M. (2008) Performance of Connections for Prefabricated Timber-Concrete Composite Floors. Materials and Structures, 41, 1533-1550.

[31] He, G., Xie, L., Wang, X., et al. (2016) Shear Behavior Study on Timber-Concrete Composite Structures with Bolts. BioResources, 11, 9205-9218.

[32] Marchi, L., Scotta, R. and Pozza, L. (2017) Experimental and Theoretical Evaluation of TCC Connections with Inclined Self-Tapping Screws. Materials and Structures, 50, 180.

[33] Mai, K.Q., Park, A. and Lee, K. (2018) Experimental and Numerical Performance of Shear Connections in CLT-Concrete Composite Floor. Materials and Structures, 51, 84.

[34] Du, H., Hu, X., Xie, Z., et al. (2019) Study on Shear Behavior of Inclined Cross Lag Screws for Glulam-Concrete Composite Beams. Construction and Building Materials, 224, 132-143.

[35] Khorsandnia, N., Valipour, H.R. and Crews, K. (2012) Experimental and Analytical Investigation of Short-Term Behaviour of LVL-Concrete Composite Connections and Beams. Construction and Building Materials, 37, 229-238.

[36] Di Nino, S., Gregori, A. and Fragiacomo, M. (2020) Experimental and Numerical Investigations on Timber-Concrete Connections with Inclined Screws. Engineering Structures, 209, 109993.

[37] Molina, J.C., Oliveira, C.A.B., Christoforo, A.L., et al. (2020) Influence of the Bonding of Rebar Dowel with Adhesive on Wood-Concrete Composite Specimens. Proceedings of the Institution of Civil Engineers - Structures and Buildings, 173, 904-913.

[38] Hehl, S., Tannert, T., Meena, R., et al. (2014) Experimental and Numerical Investigations of Groove Connections for a Novel Timber-Concrete-Composite System. Journal of Performance of Constructed Facilities, 28, A4014010.

[39] Jiang, Y. and Crocetti, R. (2019) CLT-Concrete Composite Floors with Notched Shear Connectors. Construction and Building Materials, 195, 127-139.

[40] Jiang, Y., Hu, X., Hong, W., et al. (2020) Experimental Study on Notched Connectors for Glulam-Lightweight Concrete Composite Beams. BioResources, 15, 2171-2180.

[41] Fong, L.Y., Abd Ghafar, N.H., Abd Rahman, N., et al. (2015) Connection Performance for LVL-Concrete Composite Floor System. Applied Mechanics and Materials, 773-774, 954-963.

[42] Xie, L., He, G., Wang, X., et al. (2017) Shear Capacity of Stud-Groove Connector in Glulam-Concrete Composite Structure. BioResources, 12, 4690-4706.

[43] Fernandes, F.P.D., Dias, A.A. and Neto, J.M. (2023) Experimental and Numerical Analysis on Timber-Concrete Connections with Glued Reinforcing Bars. Engineering Structures, 277, 115437.

[44] Tako, D., Denouwe, D.D., Messan, A., et al. (2023) Experimental and Numerical Investigations of Timber-Concrete Connections Using Variant Forms of Rebars. Engineering Structures, 291, 116441.

[45] Djoubissie, D.D., Messan, A., Fournely, E., et al. (2018) Experimental Study of the Mechanical Behavior of Timber-Concrete Shear Connections with Threaded Reinforcing Bars. Engineering Structures, 172, 997-1010.

[46] Djoubissie Denouwe, D., Messan, A., Fournely, E., et al. (2018) Influence of Interlayer in Timber-Concrete Composite Structures with Threaded Rebar as Shear Connector – Experimental Study. American Journal of Civil Engineering and Architecture, 6, 38-45.