Fracture Mechanism And Analysis Of Rod Glued Into Structural Glued Laminated Bamboo

Engineering bamboo products are such materials with Chinese characteristics and have avast application prospect. Especially in recent years, wood and other traditional buildingmaterials are in the case of shortage, developing new engineering bamboo products are of greatimportance. Also, in bamboo structures, the connection method is always one of the difficultproblems to be solved.This study provides a method for manufacturing a new engineering bambooproducts–structural glued laminated bamboo. This paper focus on the pull-out strength ofthread steel rods glued into structural glued laminated bamboo, the experimental results havecertain instruction significance to solve the connection problems in bamboo-based materials.This paper studies the design and manufacture process of preparing a new engineeringbamboo products-Structural glued laminated bamboo referring to design and manufacturestandards related to glulam and the physical and mechanical properties of structural gluedlaminated bamboo were also studied. The experimental results showed that the strength andmodulus of structural glued laminated bamboo meet the design requirements.The influence of geometrical parameters, such as edge distances, rod diameter andembedded length on pull-out strength were studied. The main failure modes were also analyzed.The results showed that:(1)The edge distance has no effect on failure load but has effect onfailure mode. when the edge distance was too small, It would result in structuralglued laminated bamboo being crack, accordingly, the failure load was decreased;(2) Theslenderness ratio has significant effects on pull-out strength. With the increasing of theslenderness ratio, the pull-out strength was also increased. When the slenderness ratio reaches acertain value, there exists a critical embedded depth. The yielding of the rod was occurredwhen the embedded length reaches the critical depth;(3)Three failure modes were observed in this study. There are splitting failure, a shear failure along the rod and yielding of the rod.These failure modes are similar to glulam glued-in rods.The shear stress distribution was revealed and the pull-out strength of structural gluedlaminated bamboo prediction equation was also established based on Jensen theory. Thistheory was built on the shear lag model created by Volkersen. The stress analysis method andlinear elastic fracture mechanics were used to analyses pull-out strength of structural gluedlaminated bamboo. The results showed that:(1) the distribution of tensile shear stressis notuniform along the embedded length. In pull-pull loading mode, the shear stress was big at bothends and small in the middle;(2) linear elastic fracture mechanics could be used to analysespull-out strength of structural glued laminated bamboo. The fracture energy is an importantparameter in glued in rod connection.Fracture toughness of glued in rod system was menstruated by means of compliancemethod based on Griffith and Irwin fracture theory. This method provides a new way forpredicting the pull-out strength of thread steel rods glued into structural glued laminatedbamboo.This study demonstrates the applicability of glued in rod in glulam relevant theory andmodels on structural glued laminated bamboo. The experimental values were compared withdifferent design values calculated from rod glued into glulam design models. The resultsshowed that there are no essential differences between rod glued into the glulam and structuralglued laminated bamboo. Glued-in rod technique is applicable to structural glued laminatedbamboo. The results showed that values calculated from design modes given by GIRODprogram have excellent correlation withexperimental values in thread steel rod glued intostructural glued laminated bamboo.