胶缝缺陷对木梁承载能力的影响
|
摘要
采用兴安落叶松板材、水基聚氨酯胶粘剂,分5层板胶合,制作含有不同胶缝缺陷率的3组胶合木梁试件,胶缝缺陷设置在梁的跨中。通过静力弯曲破坏试验,测试构件应力、变形及极限承载力。试验表明,胶合木梁弯曲破坏属于脆性破坏,存在受拉区外侧木纤维被拉断及胶缝缺陷处破坏两种正常破坏形态。胶缝缺陷使得木梁抗弯刚度和承载能力均降低,胶缝缺陷率2%、4%的木梁相对胶合完好的构件,极限承载能力分别降低8. 8%、13. 5%;正常使用承载能力分别降低11. 3%、14. 7%。承载能力降低幅度与胶缝缺陷率不完全成比例关系,是由于内层胶缝缺陷比外层胶缝缺陷对木梁抗弯能力影响小的原因,这表明木梁抗弯承载能力不仅与胶缝缺陷率有关,还与缺陷的位置有关。
In this paper,employing Xingan larch plank and water-based polyurethane adhesive,three groups of five-layer glulam beams were manufactured and each has different rate of glue line defects,the glue line defect is located in the midspan of the beam. The strain,deformation and ultimate bearing capacity of the components are tested by static bending destructive test. Tests showed that the bending failure of glulam beam belongs to brittle failure,there are two kinds of normal failure modes,which are the lateral wood fiber of the tensile zone is broken and the glue line defect is damaged. The flexural stiffness and bearing capacity of glulam beam will be reduced by glue line defects. Compared with an intact beam,the ultimate bearing capacity of glulam beams with a ratio of 2% and 4% glue line defect was reduced by 8. 8% and 13. 5% respectively; and the bearing capacity of normal working was reduced by 11. 3% and 14. 7% respectively. Defects in inner glue seam have less effect on the bending resistance ability of the glulam beam than external,so that the reduction of bearing capacity is not proportional to the rate of glue line defects completely. This indicates that the bending resistance ability of the glulam beam is not only related to the defect rate,but also to the location of the defects.
In this paper,employing Xingan larch plank and water-based polyurethane adhesive,three groups of five-layer glulam beams were manufactured and each has different rate of glue line defects,the glue line defect is located in the midspan of the beam. The strain,deformation and ultimate bearing capacity of the components are tested by static bending destructive test. Tests showed that the bending failure of glulam beam belongs to brittle failure,there are two kinds of normal failure modes,which are the lateral wood fiber of the tensile zone is broken and the glue line defect is damaged. The flexural stiffness and bearing capacity of glulam beam will be reduced by glue line defects. Compared with an intact beam,the ultimate bearing capacity of glulam beams with a ratio of 2% and 4% glue line defect was reduced by 8. 8% and 13. 5% respectively; and the bearing capacity of normal working was reduced by 11. 3% and 14. 7% respectively. Defects in inner glue seam have less effect on the bending resistance ability of the glulam beam than external,so that the reduction of bearing capacity is not proportional to the rate of glue line defects completely. This indicates that the bending resistance ability of the glulam beam is not only related to the defect rate,but also to the location of the defects.
引文
[1] Markus Knorz,Stefan Torno,Jan-Willem van de Kuilen. Bonding quality of industrially produced cross-laminated timber(CLT)as determined in delamination tests[J]. Construction and Building Materials,2017,133. 219-225.
[2] Feng Xu,Xiping Wang,Marko Teder,Yunfei Liu. Acoustic impact testing and waveform analysis for damage detection in glued laminated timber[J]. Holzforschung,2017,71(10). 801-811.
[3] P Dietsch,T Tannert. Assessing the integrity of glued-laminated timber elements[J]. Construction and Building Materials,2015:1259-1270.
[4] B. Franke,F. Scharmacher,and A. Müller. Assessment of the Glue-Line Quality in Glued L aminated Timber Structures[J].Materials and Joints in Timber Structures,Volume 9 of the series RILEM Bookseries,2014:395-403.
[5]王解军,黄佳,陈晓,等. PSD-V-A综合判别法在胶合木胶缝缺陷测试中的应用研究[J].中南林业科技大学学报,2016,36(6):65-69.
[6]关明杰,雍宬,王路.背面裂隙对杨木胶合界面力学性能的影响[J].南京林业大学学报(自然科学版),2014,38(5):15-19.
[7]王人杰,徐涛,陈木兰.胶合搭接连接的界面应力[J].南京航空航天大学学报,1998,30(5):538-544.
[8]邓凡臣,柴亚南,林国伟,等.复合材料加筋单元初始分层损伤参数影响分析[J].科学技术与工程,2012,12(5):1020-1024.
[9]张阿盈,邓凡尘,于飞,等.长桁与蒙皮脱粘对复合材料加筋板承载能力影响分析[J].强度与环境,2014,41(3):44-50.
[10]舒小平.复合材料层板界面缺陷的有限元分析[J].工程力学,2005,22(5):120-125.
[11]杜海深,林建平,卢志国.胶层局部缺陷对胶接接头承载能力的影响研究[J].中国胶粘剂,2009,18(2):9-11.
[12] Ludomir J. Jankowski,Tomasz Nowak. Experimental Assessment of the Glued Laminated Timber Beams in 4-Point Bending Tests and Photoelastic Coating Technique[J]. Solid State Phenomena,2016,4140(240). 155-160.
[13] F. Gaspar,H. Cruz,A. Gomes. Modeling the influence of delamination on the mechanical performance of straight glued laminated timber beams[J]. Construction and Building Materials,98(2015):447-455.
[14]周海宾,刘晓娜,韩刘杨,等.胶黏剂和指接接头对胶合木性能的影响[J].建筑材料学报,2017,20(5):752-757.
[15]郭楠,张平阳,左煜,等.竹板增强胶合木梁受弯性能[J].吉林大学学报(工学版),2017,47(3):778-788.
[16] Gliovi,Stevanovi,Petrovi. Bending behaviour of glulam beams reinforced with carbon FRP plates[J]. Journal of Civil Engineering and Management,2015,21(7). 923-932.
[17]惠卓,秦卫红,李云杰,等.胶合木端板连接节点低周反复试验与承载力[J].同济大学学报(自然科学版),2017,45(12):1765-1772.
[18]王明谦,宋晓滨,顾祥林,等.胶合木梁柱螺栓-钢填板节点转动性能研究[J].建筑结构学报,2014,35(9):141-150.
[19]周佳乐,冯新,周先雁.落叶松胶合木力学性能试验研究[J].中南林业科技大学学报,2016,36(8):125-130.
[2] Feng Xu,Xiping Wang,Marko Teder,Yunfei Liu. Acoustic impact testing and waveform analysis for damage detection in glued laminated timber[J]. Holzforschung,2017,71(10). 801-811.
[3] P Dietsch,T Tannert. Assessing the integrity of glued-laminated timber elements[J]. Construction and Building Materials,2015:1259-1270.
[4] B. Franke,F. Scharmacher,and A. Müller. Assessment of the Glue-Line Quality in Glued L aminated Timber Structures[J].Materials and Joints in Timber Structures,Volume 9 of the series RILEM Bookseries,2014:395-403.
[5]王解军,黄佳,陈晓,等. PSD-V-A综合判别法在胶合木胶缝缺陷测试中的应用研究[J].中南林业科技大学学报,2016,36(6):65-69.
[6]关明杰,雍宬,王路.背面裂隙对杨木胶合界面力学性能的影响[J].南京林业大学学报(自然科学版),2014,38(5):15-19.
[7]王人杰,徐涛,陈木兰.胶合搭接连接的界面应力[J].南京航空航天大学学报,1998,30(5):538-544.
[8]邓凡臣,柴亚南,林国伟,等.复合材料加筋单元初始分层损伤参数影响分析[J].科学技术与工程,2012,12(5):1020-1024.
[9]张阿盈,邓凡尘,于飞,等.长桁与蒙皮脱粘对复合材料加筋板承载能力影响分析[J].强度与环境,2014,41(3):44-50.
[10]舒小平.复合材料层板界面缺陷的有限元分析[J].工程力学,2005,22(5):120-125.
[11]杜海深,林建平,卢志国.胶层局部缺陷对胶接接头承载能力的影响研究[J].中国胶粘剂,2009,18(2):9-11.
[12] Ludomir J. Jankowski,Tomasz Nowak. Experimental Assessment of the Glued Laminated Timber Beams in 4-Point Bending Tests and Photoelastic Coating Technique[J]. Solid State Phenomena,2016,4140(240). 155-160.
[13] F. Gaspar,H. Cruz,A. Gomes. Modeling the influence of delamination on the mechanical performance of straight glued laminated timber beams[J]. Construction and Building Materials,98(2015):447-455.
[14]周海宾,刘晓娜,韩刘杨,等.胶黏剂和指接接头对胶合木性能的影响[J].建筑材料学报,2017,20(5):752-757.
[15]郭楠,张平阳,左煜,等.竹板增强胶合木梁受弯性能[J].吉林大学学报(工学版),2017,47(3):778-788.
[16] Gliovi,Stevanovi,Petrovi. Bending behaviour of glulam beams reinforced with carbon FRP plates[J]. Journal of Civil Engineering and Management,2015,21(7). 923-932.
[17]惠卓,秦卫红,李云杰,等.胶合木端板连接节点低周反复试验与承载力[J].同济大学学报(自然科学版),2017,45(12):1765-1772.
[18]王明谦,宋晓滨,顾祥林,等.胶合木梁柱螺栓-钢填板节点转动性能研究[J].建筑结构学报,2014,35(9):141-150.
[19]周佳乐,冯新,周先雁.落叶松胶合木力学性能试验研究[J].中南林业科技大学学报,2016,36(8):125-130.