Evaluating the Role of Mechanical Connections and Reinforcements in Modular Timber Beam Behaviour

  • Mohd Rizuwan Mamat Faculty of Civil Engineering, Universiti Teknologi MARA, Shah Alam, Selangor, MALAYSIA and Forest Research Institute Malaysia (FRIM), Kepong, Selangor, MALAYSIA
  • Mohd Hisbany Mohd Hashim Faculty of Civil Engineering, Universiti Teknologi MARA, Shah Alam, Selangor, MALAYSIA and 3R: Rehabilitation, Repair and Retrofitting Group, Faculty of Civil Engineering, Universiti Teknologi MARA, Shah Alam, Selangor, MALAYSIA
  • Noorsuhada Md Nor Faculty of Civil Engineering, Universiti Teknologi MARA, Permatang Pauh, Pulau Pinang, MALAYSIA and Material and Structural Integrity Research Group, Civil Engineering Studies, Universiti Teknologi MARA, Permatang Pauh, Pulau Pinang, MALAYSIA
DOI: https://doi.org/10.22146/jcef.21594
Keywords: Modular timber beams;, Chopped Strand Mat, Stiffness degradation, Timber-bolt connections, Segmented beam behaviour

Abstract

Modular timber construction faces critical challenges in connection performance, with mechanical joints representing the weakest structural elements in segmented systems, particularly for rapid-deployment infrastructure applications such as temporary forest bridges. This research addresses the fundamental knowledge gap regarding the combined effects of mechanical connections and reinforcement strategies on modular timber beam structural behavior. The study investigates modular timber beam flexural performance through experimental evaluation of steel U-shaped connectors and Chopped Strand Mat (CSM) reinforcement applied to the tension zones, examining how beam segmentation affects structural integrity. Ten I-section modular timber beams with lattice-web configuration underwent three-point bending tests using a Shimadzu AG-IS 100 kN Universal Testing Machine at 6.6 mm/min loading rate, with specimens spanning 3.0 meters supported at 2.7-meter intervals. Test specimens featured varying segmentation patterns (0.6m, 0.75m, 1.0m, and 1.5m segment lengths) connected via U-shaped steel connectors and bolts, with selected beams receiving 5mm thick CSM reinforcement at the bottom flanges. Mechanical properties including modulus of elasticity (MOE), modulus of rupture (MOR), and flexural stiffness were systematically measured to quantify reinforcement and segmentation effects on joint behavior and structural continuity. Results demonstrate that CSM reinforcement provides substantial performance improvements, with ETR136 achieving a 49% increase in ultimate load capacity (29,397 N vs 19,709 N for ETN131) and superior ductility characteristics. However, segmentation introduces significant structural vulnerabilities, with five-segment beams (ETN50.65) showing a 49.5% capacity reduction compared to continuous specimens. The research reveals that while CSM reinforcement effectively delays crack initiation and reduces peak tensile strain by an average of 31%, mechanical joints remain critical failure points due to stress concentrations at the timber-bolt interfaces. The three-segment configuration emerges as optimal for balancing structural performance with practical modularity requirements. These findings provide essential design guidance for modular timber systems in rapid-deployment applications, emphasizing the need for optimized connection strategies and hybrid reinforcement techniques to enhance the structural integrity and durability of segmented timber infrastructure.

References

ASTM International (2021a), ‘D0198-21a standard test methods of static tests of lumber in structural sizes’. PA: ASTM International. URL: https://doi.org/10.1520/d0198-21a

ASTM International (2021b), ‘D5652-21 standard test methods for single-bolt connections in wood and wood-based products’. PA: ASTM International. URL: https://doi.org/10.1520/d5652-21

Boafo, F. E., Kim, J.-H. and Kim, J.-T. (2016), ‘Performance of Modular Prefabricated Architecture: Case Study-Based Review and Future Pathways’, Sustainability 8(6), 558. URL:https://doi.org/10.3390/su8060558

Chen, J., Wang, H., Yu, Y., Liu, Y. and Jiang, D. (2020), ‘Loosening of Bolted Connections under Transverse Loading in Timber Structures’, Forests 11(8), 816. URL:https://doi.org/10.3390/f11080816

Franke, S., Franke, B. and Harte, A. M. (2015), ‘Failure modes and reinforcement techniques for timber beams-State of the art’, Construction and Building Materials 97, 2–13. URL: https://doi.org/10.1016/j.conbuildmat.2015.06.021

Hu, Y., Wei, Y., Chen, S., Yan, Y. and Zhang, W. (2021), ‘Experimental Study on Timber−Lightweight Concrete Composite Beams with Ductile Bolt Connectors’, Materials 14(10), 2632. URL: https://doi.org/10.3390/ma14102632

Huang, H., Chang, W. and Chen, K. (2019), ‘Study of SMA-dowelled timber connection reinforced by densified veneer wood under cyclic loading’, MATEC Web of Conferences 275, 1015. URL: https://doi.org/10.1051/matecconf/201927501015

Karagiannis, V., Málaga-Chuquitaype, C. and Elghazouli, A. Y. (2016), ‘Behaviour of hybrid timber beamto-tubular steel column moment connections’, Engineering Structures 131, 243. URL: https://doi.org/10.1016/j.engstruct.2016.11.006

KrĆŸan, M., Pazlar, T. and Ber, B. (2023), ‘Composite Beams Made of Waste Wood-Particle Boards, Fastened to Solid Timber Frame by Dowel-Type Fasteners’, Materials 16(6), 2426. URL: https://doi.org/10.3390/ma16062426

Lee, S.-S., Park, K.-S., Jung, J.-S. and Lee, K.-S. (2020),‘Evaluation of the Structural Performance of a Novel Methodology for Connecting Modular Units Using Straight and Cross-Shaped Connector Plates in Modular Buildings’, Applied Sciences 10(22), 8186. URL: https://doi.org/10.3390/app10228186

Liu, Y. and Xiong, H. (2018), ‘Lateral performance of a semi-rigid timber frame structure: theoretical analysis and experimental study’, Journal of Wood Science 64(5), 591. URL: https://doi.org/10.1007/s10086-018-1727-7

Lokaj, A., Dobeơ, P. and Sucharda, O. (2020), ‘Effects of Loaded End Distance and Moisture Content on the Behavior of Bolted Connections in Squared and Round Timber Subjected to Tension Parallel to the Grain’, Materials 13(23), 5525. URL: https://doi.org/10.3390/ma13235525

Mamat, M. R., Hashim, M. H. M. and Nor, N. M. (2025),‘Reassessing Tension Side Reinforcement in Modular Timber Beams: Insights from Experimental ModalAnalysis in Forest Bridge Systems’, Jurnal Kejuruteraan 37(3), 1131–1144. URL: https://doi.org/10.17576/jkukm-2025-37(3)-05

Manalo, A. and Mutsuyoshi, H. (2011), ‘Behavior of fiber-reinforced composite beams with mechanical joints’, Journal of Composite Materials 46(4), 483. URL: https://doi.org/10.1177/0021998311418263

Mirski, R., KuliƄski, M., Dziurka, D., Thomas, M. and Antonowicz, R. (2021), ‘Strength Properties of Structural Glulam Elements from Pine (Pinus sylvestris L.) Timber Reinforced in the Tensile Zone with Steel and Basalt Rods’, Materials 14(10), 2574. URL: https://doi.org/10.3390/ma14102574

Okunrounmu, O., Salem, O. and Hadjisophocleous, G. (2022), ‘Fire performance of hybrid mass timber beamend connections with perpendicular-to-wood grain reinforcement’, Journal of Structural Fire Engineering 13(4), 433. URL: https://doi.org/10.1108/jsfe-06-2021-0036

Rahman, M. J., Hasrul, M., Ashad, H., Yusuf, F. A. and Hasrul, N. R. (2024), ‘An Assessment Of Derelict Building Constructions Situated In Coastal Regions’, Journal of the Civil Engineering Forum 10(3), 229. URL: https://doi.org/10.22146/jcef.10433

Rebouças, A. S., Mehdipour, Z., Branco, J. M. and LourĂ©nço, P. B. (2022), ‘Ductile Moment-Resisting Timber Connections: A Review’, Buildings 12(2), 240. URL: https://doi.org/10.3390/buildings12020240

Schiro, G., Giongo, I., Sebastian, W., Riccadonna, D. and Piazza, M. (2018), ‘Testing of timber-to-timber screwconnections in hybrid configurations’, Construction and Building Materials 171, 170. URL: https://doi.org/10.1016/j.conbuildmat.2018.03.078

Shi, D., Xu, Y., Demartino, C., Xiao, Y. and Spencer, B. F. (2023), ‘Bio-based laminated truss structures with bolted steel connections: Experiment, modeling, and model-updating’, Earthquake Engineering & Structural Dynamics 53(2), 739. URL: https://doi.org/10.1002/eqe.4043

Shu, Z., Ning, B., Chen, J., Li, Z., He, M., Luo, J. and Dong, H. (2022), ‘Reinforced moment-resisting glulam bolted connection with coupled long steel rod with screwheads for modern timber frame structures’, Earthquake Engineering & Structural Dynamics 52(4), 845. URL: https://doi.org/10.1002/eqe.3789

Wang, G., Xian, B., Ma, F. and Fang, S. (2024), ‘Shear Performance of Prefabricated Steel Ultra-High-Performance Concrete (UHPC) Composite Beams under Combined Tensile and Shear Loads: Single Embedded Nut Bolts vs. Studs’, Buildings 14(8), 2425. URL: https://doi.org/10.3390/buildings14082425

Wang, Y., Xia, J., Ma, R., Xu, B. and Wang, T. (2019), ‘Experimental Study on the Flexural Behavior of an Innovative Modular Steel Building Connection with Installed Bolts in the Columns’, Applied Sciences 9(17), 3468. URL: https://doi.org/10.3390/app9173468

Wdowiak-Postulak, A. (2020), ‘Basalt Fibre Reinforcement of Bent Heterogeneous Glued Laminated Beams’, Materials 14(1), 51. URL: https://doi.org/10.3390/ma14010051

Wdowiak-Postulak, A., Gocál, J., Bahleda, F. and Prokop, J. (2023), ‘Load and Deformation Analysis in Experimental and Numerical Studies of Full-Size Wooden Beams Reinforced with Prestressed FRP and Steel Bars’, Applied Sciences 13(24), 13178. URL: https://doi.org/10.3390/app132413178

Wdowiak-Postulak, A., ƚwit, G. and Dziedzic-Jagocka, I. (2024), ‘Application of Composite Bars in Wooden, Full-Scale, Innovative Engineering Products—Experimental and Numerical Study’, Materials 17(3), 730. URL: https://doi.org/10.3390/ma17030730

Yang, R., Li, H., Lorenzo, R., Ashraf, M., Sun, Y. and Yuan, Q. (2020), ‘Mechanical behaviour of steel timber composite shear connections’, Construction and Building Materials 258, 119605. URL: https://doi.org/10.1016/j.conbuildmat.2020.11960522

Published
2025-09-16
How to Cite
Mamat, M. R., Mohd Hashim, M. H., & Md Nor, N. (2025). Evaluating the Role of Mechanical Connections and Reinforcements in Modular Timber Beam Behaviour. Journal of the Civil Engineering Forum, 12(1), 11-22. https://doi.org/10.22146/jcef.21594
Issue
Vol. 12 No. 1 (January 2026)
Section
Articles

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