Perpendicular-to-Grain Behaviour of Bolted Steel-to-Timber Connections: A State-of-the-Art Review

Yi Cui

doi:10.63313/AERpc.9128

Authors

Yi Cui College of Civil Engineering, Central South University of Forestry and Technology, Changsha, 410000, China Author

DOI:

https://doi.org/10.63313/AERpc.9128

Keywords:

Timber Connections, Bolted Joints, Perpendicular-to-Grain, Embedment Strength, Splitting Failure, Ductility, Group Effect

Abstract

This paper reviews the perpendicular-to-grain mechanical behaviour of bolted steel-to-timber connections, focusing on embedment strength, slip modulus, ductility, and splitting failure. The review synthesizes experimental and theoretical studies from major design codes (Eurocode 5, NDS, GB 50005) and recent research. Key findings indicate that embedment strength depends on density, fastener diameter, moisture content, and loading angle; the bending-specimen test method better reflects actual joint conditions. Slip modulus and group effect lack unified models, and ductility evaluation standards are inconsistent. Fracture-mechanics-based models for splitting resistance show improved accuracy but need further validation for multi-bolt configurations. Finally, the paper outlines four research tasks: (1) perpendicular embedment tests using bending specimens, (2) an initial slip modulus formula based on beam-on-elastic-foundation theory, (3) a group reduction factor for multiple bolts, and (4) an optimised design method for perpendicular load capacity. This review highlights research gaps and provides a basis for future code improvements.

References

[1] Liu, W.Q., Yang, H.F. (2019). Research progress of modern timber structures. Journal of Building Structures, 40(2), 16-43. (in Chinese)

[2] Hansson, E.F. (2011). Analysis of structural failures in timber structures. Engineering Structures, 33(11), 2978-2982.

[3] Johansen, K.W. (1949). Theory of timber connections. International Association for Bridge and Structural Engineering, 9, 249-262.

[4] Ehlbeck, J., Werner, H. (1992). Softwood and hardwood embedding strength for dowel type fasteners. CIB-W18 Meeting, Paper 25-7-2.

[5] Eurocode 5 (2004). EN 1995-1-1. Brussels: CEN.

[6] Molina, J.C., et al. (2017). Embedment strength of dowels in wood according to ABNT NBR 7190 and EUROCODE 5. International Engineering Journal, 70(1), 9-17.

[7] Molina, J.C., et al. (2017). Embedment strength of steel dowel in wood according to ABNT NBR 7190:1997 and ASTM D5764:2007. Ingeniare, 25(3), 492-500.

[8] NBR 7190 (1997). Brazilian standard for timber structures.

[9] EN 383 (2007). Timber structures – Determination of embedding strength.

[10] ASTM D5764 (2013). Standard test method for dowel-bearing strength.

[11] Santos, C.L., et al. (2010). A comparison between EN 383 and ASTM D5764. Strain, 46, 159-174.

[12] Feng, X., et al. (2023). Embedment strength of wood perpendicular to grain. Journal of Building Materials, 26(6), 644-652. (in Chinese)

[13] GB 50005 (2017). Standard for design of timber structures. (in Chinese)

[14] Xu, X.Y., et al. (2019). Effect of loading direction on embedment strength of spruce glulam. Journal of Architecture, 50(4), 419-422. (in Chinese)

[15] NDS (1997). National design specification for wood construction.

[16] Sandhaas, C., et al. (2013). Embedment tests parallel to grain and ductility. European Journal of Wood and Wood Products, 71, 599-608.

[17] Fahlbusch, H. (1949). Report No. 49-09. Braunschweig.

[18] Winistorfer, S.G. (1994). Validation of European yield model for nailed connections. Structures Congress 94, Atlanta.

[19] Koponen, S. (1991). Embedding characteristics of wood in grain direction. Helsinki Univ. of Technology.

[20] Karagiannis, V., et al. (2016). Modified foundation modelling of dowel embedment in glulam. Construction and Building Materials, 102, 1168-1179.

[21] Sawata, K., Yasumura, M. (2002). Determination of embedding strength of wood. Journal of Wood Science, 48, 138-146.

[22] Zitto, M.A.S., et al. (2012). Embedding strength in joints of Eucalyptus grandis. European Journal of Wood and Wood Products, 70, 433-440.

[23] Schneid, E., Moraes, P.D. (2017). Grain angle and temperature effect on embedding strength. Construction and Building Materials, 150, 442-449.

[24] Schoenmakers, J.C.M., Svensson, S. (2011). Embedment tests perpendicular to grain – optical measurements. European Journal of Wood and Wood Products, 69, 133-142.

[25] Van der Put, T.A.C.M. (2008). Explanation of embedding strength of particle board. Holz Roh-Werkst, 66(4), 259-265.

[26] Van der Put, T.A.C.M. (2008). Derivation of bearing strength perpendicular to grain. Holz Roh-Werkst, 66(6), 409-417.

[27] Lederer, W., et al. (2016). Influence of reinforcements on embedment behaviour of steel dowels. European Journal of Wood and Wood Products, 74, 793-807.

[28] Yurrita, M., Cabrero, J.M. (2018). New criteria for parallel-to-grain embedment strength. Construction and Building Materials, 173, 238-250.

[29] Seri, N.A.B., et al. (2015). Dowel-bearing strength of glulam with and without glue line. Proc. ICCE 2015, 1007, 978-981.

[30] Zhang, G., et al. (2014). Determination of embedment strength in bolted timber connections. China Forest Products Industry, 4(8), 22-26. (in Chinese)

[31] Wang, W.D., et al. (2023). Bearing performance of bamboo scrimber dowel at various loading angles. Journal of Forestry Engineering, 8(4), 167-174. (in Chinese)

[32] Yang, R.Y., et al. (2020). Yield strength of larch parallel-to-grain embedment. Journal of Forestry Engineering, 5(5), 131-138. (in Chinese)

[33] You, J., et al. (2018). Experimental study on embedment strength of Korean pine. Wood Processing Machinery, 29(2), 24-28. (in Chinese)

[34] Cui, Z.Y., et al. (2017). Embedment strength of bamboo scrimber parallel to grain at elevated temperatures. Journal of Southeast University (Natural Sci.), 47(6), 1174-1179. (in Chinese)

[35] Xu, J.H., et al. (2021). Embedment strength of domestic Japanese larch CLT. Journal of Beijing Forestry University, 43(12), 116-126. (in Chinese)

[36] Zhang, J.Z., et al. (2014). Factors affecting embedment strength of Japanese larch glulam. Wood Industry, 28(3), 22-29. (in Chinese)

[37] Ma, G.J., et al. (2016). Effect of humidity on embedment strength of glulam. Journal of Architecture and Civil Engineering, 33(1), 121-126. (in Chinese)

[38] Ogawa, K., et al. (2022). Embedment properties of resin-impregnated Japanese cedar. Journal of Wood Science, 68, 9.

[39] Hwang, K., Komatsu, K. (2002). Bearing properties of engineered wood products I. Journal of Wood Science, 48, 295-301.

[40] Hong, J.P., Barrett, D. (2010). 3D finite-element modeling of nailed connections. Journal of Structural Engineering, 136(6).

[41] Gattesco, N. (1998). Strength and local deformability of wood beneath bolted connectors. Journal of Structural Engineering, 124(2), 195-202.

[42] Schweigler, M., et al. (2016). Load-to-grain angle dependence of embedment behaviour in LVL. Construction and Building Materials, 09, 051.

[43] Jockwer, R., et al. (2022). Evaluation of parameters influencing load-deformation behaviour of dowel-type connections. Wood Material Science & Engineering, 17(1).

[44] Jorissen, A., Fragiacomo, M. (2011). General notes on ductility in timber structures. Engineering Structures, 33(11), 2987-2997.

[45] Malo, K.A., et al. (2011). Quantifying ductility in timber structures. Engineering Structures, 33(11), 2998-3006.

[46] Xu, B.H., et al. (2024). Mechanical behaviour of timber joints with multiple densified wood dowels parallel to grain. Journal of Structural Engineering, 150(10).

[47] Pyner, G.R., Matthews, F.L. (1979). Comparison of single and multi-hole bolted joints in GFRP. Journal of Composite Materials, 13(232).

[48] Patel, M.C., Hindman, D.P. (2012). Comparison of single- and two-bolted LVL perpendicular-to-grain connections. Journal of Materials in Civil Engineering, 24, 339-346.

[49] Van der Put, T.A.C.M., Leijten, A.J.M. (2000). Evaluation of perpendicular to grain failure. CIB-W18, Paper 33-7-7.

[50] Schoenmakers, J.C.M. (2010). Fracture and failure mechanisms in timber loaded perpendicular to grain. PhD thesis, TU Eindhoven.

[51] Schoenmakers, J.C.M., Jorissen, A.J.M. (2011). Failure mechanisms of dowel-type connections perpendicular to grain. Engineering Structures, 33(11), 3054-3063.

[52] Zarnani, P., Quenneville, P. (2013). Wood splitting capacity in timber connections loaded transversely. CIB-W18, Paper 46-7-5.

[53] Franke, B., Quenneville, P. (2010). Failure behaviour and resistance of dowel-type connections loaded perpendicular to grain. CIB-W18, Paper 43-7-6.

[54] Franke, B., Quenneville, P. (2011). Design approach for splitting failure of dowel-type connections. CIB-W18, Paper 44-7-5.

[55] Jensen, J.L. (2003). A tensile fracture model for joints with rods or dowels loaded perpendicular to grain. CIB-W18, Paper 36-7-9.

[56] Jensen, J.L., Quenneville, P. (2011). Experimental investigations on row shear and splitting in bolted connections. Construction and Building Materials, 25(5), 2420-2425.

[57] Jensen, J.L., et al. (2012). Splitting of timber beams loaded perpendicular to grain by connections – combined effect of edge and end distance. Construction and Building Materials, 35.

[58] Jensen, J.L. (2003). Splitting strength of beams loaded by connections. CIB-W18, Paper 36-7-8.

[59] Jensen, J.L., et al. (2015). Brittle failures in timber beams loaded perpendicular to grain by connections. J. Mater. Civ. Eng., 27.

[60] Jensen, J.L., Quenneville, P. (2011). Fracture mechanics analysis of row shear failure in dowelled timber connections. Materials and Structures, 44(1), 351-360.

[61] Jensen, J.L. (2005). Quasi-non-linear fracture mechanics analysis of splitting failure of single dowel joints. Journal of Wood Science, 51(6), 559-565.

[62] Jensen, J.L. (2005). Splitting strength of beams loaded perpendicular to grain by dowel joints. Journal of Wood Science, 51(5), 480-485.

[63] DIN 1052 (2004). Design of timber structures.

[64] Fan, C.M. (1982). Working principle and calculation formula of bolted timber connections. Journal of Harbin Architectural Engineering Institute, (1), 18-36. (in Chinese)

[65] Fan, C.M., et al. (1985). Bearing capacity of bolted timber connections – suggestions for ISO design code. Journal of Harbin Architectural Engineering Institute, (2), 16-30. (in Chinese)

[66] Fan, C.M. (1986). Basic principles for deriving bolted connection formulae based on elastoplastic theory. Journal of Harbin Architectural Engineering Institute, (3), 137-141. (in Chinese)

[67] Xu, D.L., et al. (2009). Experimental study on bearing capacity of wood-steel-filled-plate bolted connections. Journal of Nanjing Tech University (Natural Sci.), 31(1), 87-91. (in Chinese)

[68] Xu, D.L., et al. (2009). Experimental study on wood-steel-splint bolted connections. Jiangsu Construction, 127(3), 18-20. (in Chinese)

[69] Xu, D.L., et al. (2011). Experimental study on mechanical properties of glulam-to-glulam bolted connections. Journal of Building Structures, 32(7), 93-100. (in Chinese)

[70] Xu, D.L., et al. (2011). Experimental study on mechanical properties of glulam with external steel plates and multiple bolted connections. Journal of Nanjing Tech University (Natural Sci.), 33(5), 29-35. (in Chinese)

[71] Zhu, E.C., et al. (2020). Calculation analysis and experimental study on bearing capacity of steel plate bolted timber connections. Journal of Building Structures, 41(1), 113-121. (in Chinese)

[72] Zhu, E.C., et al. (2016). Experimental study and design value determination of bolted timber connections. Journal of Building Structures, 37(4), 54-63. (in Chinese)

[73] Wang, Z.H., et al. (2020). Perpendicular-to-grain bearing performance of embedded steel plate-dowel connections in Japanese cedar. Scientia Silvae Sinicae, 56(7), 123-134. (in Chinese)

[74] Song, X.B., et al. (2018). Fracture-mechanics-based algorithm for perpendicular tensile capacity of bolted timber connections. Journal of Building Structures, 39(S2), 228-232. (in Chinese)

[75] Cui, Z.Y., et al. (2024). Mechanical performance of bamboo scrimber-steel-filled-plate bolted connections. Journal of Huazhong University of Science & Technology (Natural Sci.), 52(1), 141-148. (in Chinese)

[76] Li, X.Z., et al. (2012). Research status on bolted connection performance and influencing factors in modern timber structures. World Forestry Research, 25(4), 52-57. (in Chinese)