{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T01:45:52Z","timestamp":1790819152261,"version":"4.1.0"},"reference-count":34,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,21]],"date-time":"2026-08-21T00:00:00Z","timestamp":1787270400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005632","name":"the National Centre for Research and Development","doi-asserted-by":"crossref","award":["LIDER15\/0052\/2024"],"award-info":[{"award-number":["LIDER15\/0052\/2024"]}],"id":[{"id":"10.13039\/501100005632","id-type":"DOI","asserted-by":"crossref"}]},{"award":["LIDER15\/0052\/2024"],"award-info":[{"award-number":["LIDER15\/0052\/2024"]}],"id":[{"id":"https:\/\/ror.org\/05pwfyy15","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Metal-plate-connected (MPC) joints govern the stiffness and load-bearing performance of many prefabricated timber roof trusses, yet their response to repeated moisture changes remains critical for serviceability and durability. This study evaluated five continuous C24 Norway spruce reference specimens and fifteen specimens joined with GNA20-MIT nail plates using sequential four-point-bending stiffness measurements and wetting\u2013drying conditioning. Test I was used as the initial stiffness stage, whereas Tests II and III followed successive 24 h water-immersion and 6-day natural-drying intervals; the specimens were subsequently tested to failure. The mean apparent modulus of elasticity of the MPC specimens decreased from 1.39 to 1.22 GPa (approximately 12%), but a Friedman repeated-measures test did not show a statistically significant stage effect (\u03c72(2) = 4.13, p = 0.127). Because the same specimens were repeatedly loaded, and no unexposed MPC control group was included, this change cannot be attributed exclusively to moisture cycling. In the primary analysis retaining all 15 MPC specimens, the mean apparent bending strength of the connected elements was 16.92 MPa, compared with 34.14 MPa for the structurally different continuous reference specimens; excluding M7 yielded 17.87 MPa only as a sensitivity analysis. Failure of the connected specimens was progressive and dominated by plate slip and partial spike withdrawal, whereas solid specimens failed more abruptly in bending. The results therefore support attention to connection flexibility and serviceability under variable environmental and loading histories, while further controlled testing is required to isolate the specific contribution of moisture cycling.<\/jats:p>","DOI":"10.3390\/ma19163542","type":"journal-article","created":{"date-parts":[[2026,8,21]],"date-time":"2026-08-21T08:14:01Z","timestamp":1787300041000},"page":"3542","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Strength of Wooden Truss Connections with Nail Plates Under Cyclic Humidity Changes"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4867-195X","authenticated-orcid":false,"given":"Marek","family":"Wieruszewski","sequence":"first","affiliation":[{"name":"Department of Mechanical Wood Technology, Pozna\u0144 University of Life Sciences, 60-637 Pozna\u0144, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Adam","family":"Czerwi\u0144ski","sequence":"additional","affiliation":[{"name":"Department of Mechanical Wood Technology, Pozna\u0144 University of Life Sciences, 60-637 Pozna\u0144, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0022-8534","authenticated-orcid":false,"given":"Agnieszka Katarzyna","family":"Wdowiak-Postulak","sequence":"additional","affiliation":[{"name":"Department of Materials Strength and Structural Diagnostics, Kielce University of Technology, 25-314 Kielce, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9832-9274","authenticated-orcid":false,"given":"Maciej","family":"Jarz\u0119bski","sequence":"additional","affiliation":[{"name":"Department of Physics and Biophysics, Faculty of Food Science and Nutrition, Pozna\u0144 University of Life Sciences, Wojska Polskiego 38\/42, 60-637 Pozna\u0144, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Adrian","family":"Troci\u0144ski","sequence":"additional","affiliation":[{"name":"Department of Mechanical Wood Technology, Pozna\u0144 University of Life Sciences, 60-637 Pozna\u0144, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,21]]},"reference":[{"key":"ref_1","unstructured":"Blass, H.J., and Sandhaas, C. (2017). Timber Engineering\u2014Principles for Design, KIT Scientific Publishing."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1007\/s43452-025-01123-8","article-title":"Investigations on structural-sized GLT beams reinforced with steel and FRP composite bars\u2014Experimental tests and non-linear numerical approach","volume":"25","author":"Kawecki","year":"2025","journal-title":"Arch. Civ. Mech. Eng."},{"key":"ref_3","unstructured":"Piazza, M., Tomasi, R., and Modena, R. (2005). Strutture in Legno: Materiale, Calcolo e Progetto Secondo le Nuove Normative Europee, Hoepli."},{"key":"ref_4","unstructured":"(2008). Eurocode 5\u2014Design of Timber Structures\u2014Part 1\u20131: General\u2014Common Rules and Rules for Buildings (Standard No. EN 1995-1-1:2004+A1:2008)."},{"key":"ref_5","unstructured":"(2022). National Design Standard for Metal Plate Connected Wood Truss Construction (Standard No. ANSI\/TPI 1-2022)."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"105056","DOI":"10.1016\/j.jobe.2022.105056","article-title":"Review on research progress of metal-plate-connected wood joints","volume":"59","author":"Ling","year":"2022","journal-title":"J. Build. Eng."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1520\/JTE11774","article-title":"Small-scale modeling of metal-plate-connected wood truss joints","volume":"33","author":"Gupta","year":"2005","journal-title":"J. Test. Eval."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"622","DOI":"10.1139\/l93-079","article-title":"Strength and stiffness of glulam trusses with punched metal plated joints","volume":"20","author":"Karacabeyli","year":"1993","journal-title":"Can. J. Civ. Eng."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1016\/S0950-0618(00)00015-5","article-title":"Punched metal plate timber fasteners under fatigue loading","volume":"14","author":"Karadelis","year":"2000","journal-title":"Constr. Build. Mater."},{"key":"ref_10","unstructured":"Groom, L.H. (1995). Effect of Moisture Cycling on Mechanical Response of Metal-Plate Connector Joints, USDA Forest Service. Research Paper SO-291."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"748","DOI":"10.1061\/(ASCE)CF.1943-5509.0000271","article-title":"Performance of metal-plated wood joints exposed to periods of soaking moisture","volume":"26","author":"Mtenga","year":"2012","journal-title":"J. Perform. Constr. Facil."},{"key":"ref_12","unstructured":"(2016). Structural Timber\u2014Strength Classes (Standard No. EN 338:2016)."},{"key":"ref_13","unstructured":"(2008). Timber Structures\u2014Connectors\u2014Requirements (Standard No. BS EN 14545:2008)."},{"key":"ref_14","unstructured":"MiTek Industries (2026, July 14). GNA20 Metal Connector Plate\u2014Technical and Product Information. Available online: https:\/\/www.mitek.pl\/."},{"key":"ref_15","unstructured":"(2012). Timber Structures\u2014Structural Timber and Glued Laminated Timber\u2014Determination of Some Physical and Mechanical Properties (Standard No. EN 408:2010+A1:2012)."},{"key":"ref_16","unstructured":"(1963). Physical and Mechanical Properties of Wood\u2014Determination of the Modulus of Elasticity in Static Bending (Standard No. PN-63\/D-04117)."},{"key":"ref_17","unstructured":"(1977). Wood\u2014Determination of Static Bending Strength (Standard No. PN-77\/D-04103)."},{"key":"ref_18","unstructured":"(2011). Structural Timber\u2014Determination of Characteristic Values of Mechanical Properties and Density (Standard No. PN-EN 384:2011)."},{"key":"ref_19","unstructured":"(2000). Wood Preservatives\u2014Accelerated Ageing of Treated Wood Prior to Biological Testing\u2014Leaching Procedure (Standard No. PN-EN 84:2000)."},{"key":"ref_20","unstructured":"(1993). Wood Preservatives\u2014Accelerated Ageing of Protected Wood Prior to Biological Testing\u2014Evaporative Ageing Procedure (Standard No. PN-EN 73:1993)."},{"key":"ref_21","unstructured":"(2004). Moisture Content of Sawn Timber\u2014Part 2: Determination of Moisture Content by Electrical Resistance Method (Standard No. PN-EN 13183-2:2004)."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1520\/JTE12676J","article-title":"Testing and evaluation of metal-plate-connected wood truss joints","volume":"24","author":"Vatovec","year":"1996","journal-title":"J. Test. Eval."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1061\/(ASCE)0733-9445(2006)132:3(409)","article-title":"Finite-element modeling of timber joints with punched metal plate fasteners","volume":"132","author":"Ellegaard","year":"2006","journal-title":"J. Struct. Eng."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1011","DOI":"10.13031\/2013.28695","article-title":"Analysis of metal-plate-connected timber trusses with semi-rigid joints","volume":"35","author":"Gupta","year":"1992","journal-title":"Trans. ASAE"},{"key":"ref_25","first-page":"55","article-title":"Lumber connection performance under cyclic moisture conditions","volume":"45","author":"Falk","year":"1995","journal-title":"For. Prod. J."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1971","DOI":"10.1061\/(ASCE)0733-9445(1990)116:7(1971)","article-title":"Destructive Testing of Metal-Plate-Connected Wood Truss Joints","volume":"116","author":"Gupta","year":"1990","journal-title":"J. Struct. Eng."},{"key":"ref_27","unstructured":"Larsen, H.J. (2002, January 16\u201319). Design of Timber Structures with Metal Plate Connections under Humidity Variations. Proceedings of the CIB-W18 Meeting 35, Kyoto, Japan."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Madsen, B. (2000). Behavior of Timber Connections, Timber Engineering Ltd.","DOI":"10.1139\/l01-016"},{"key":"ref_29","unstructured":"Yasumura, M., and Kawai, N. (1998, January 17\u201320). Estimating Seismic Performance of Wood-Framed Structures. Proceedings of the 5th World Conference on Timber Engineering (WCTE 1998), Montreux, Switzerland."},{"key":"ref_30","unstructured":"Smith, I., Landis, E., and Gong, M. (2003). Fracture and Fatigue in Wood, John Wiley & Sons."},{"key":"ref_31","unstructured":"Fr\u00fchwald, E., and Hansson, E. (2008). Serviceability of Timber Structures in Variable Climate Conditions, Lund University."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1016\/j.conbuildmat.2015.05.089","article-title":"Analysis and strengthening of carpentry joints","volume":"97","author":"Branco","year":"2015","journal-title":"Constr. Build. Mater."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Matwiej, \u0141., Wiaderek, K., Jarecki, W., Orlikowski, D., and Wieruszewski, M. (2025). Modelling upholstered furniture frames using the finite element method. Appl. Sci., 15.","DOI":"10.3390\/app15020926"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Matwiej, \u0141., Wieruszewski, M., Wiaderek, K., and Pa\u0142ubicki, B. (2022). Elements of designing upholstered furniture sandwich frames using finite element method. Materials, 15.","DOI":"10.3390\/ma15176084"}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/16\/3542\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T04:11:49Z","timestamp":1787458309000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/16\/3542"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,21]]},"references-count":34,"journal-issue":{"issue":"16","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["ma19163542"],"URL":"https:\/\/doi.org\/10.3390\/ma19163542","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,21]]}}}