Investigation Of Structrual Behaviour Of I-joists And Shearwalls Utilizing Small-diameter Timber

Wood is a green,environmentally friendly and renewable natural resource.It has a unique position in the field of architecture since ancient times.From the primitive shack built in ancient times to various timber structure buildings designed by standardization,timber structure has always been accompanied by the development of human civilization.Timber structure also has the advantages of convenient construction,sound insulation and heat insulation,comfortable living,energy saving and environmental protection,among which light wood frame construction is widely used in foreign countries,but light wood frame construction is difficult to be popularized in China because of its high construction cost due to the import dependence of dimension lumbers,wall panels,metal connectors,etc.In this paper,small-diameter timber built-up stud and small-diameter timber I-joists are processed by sawing,wood screw connection and other conventional(low threshold)technical means through rational design.Through experimental research,the purpose of replacing the dimension lumbers in light wood frame construction is achieved.It not only makes rational use of local natural resources,but also reduces the construction cost,which is more conducive to the promotion of light wood frame construction in China.Twenty-four small-diameter timber composite shear walls were fabricated,which were divided into monotonic loading and reciprocating loading.Twelve small-diameter timber shear walls were tested under monotonic loading and 12 small-diameter timber shear walls were tested under reciprocating loading.The load-displacement curves of the shear walls were obtained by monotonic loading.The hysteretic curves of shear walls are obtained by loading,and the skeleton curves of shear walls are sorted out.The bearing capacity,deformation characteristics and failure phenomena of shear walls under monotonic and reciprocating loads are studied.The effects of different wall panels,the change of spacing between wall stud,type of end-wall studs on the mechanical properties of shear walls are studied.Analysis of the wind and seismic performance of shear walls is carried out in terms of shear strength,shear stiffness,yield displacement,yield load and ductility.Twenty small-diameter timber I-joists were fabricated.The webs of ten of them were made of structural plywood,another webs of I-joists were OSB boards,and two of them constitute one specimen for three-point loading.The load-displacement curves and failure modes of the I-joists were obtained through experiments.The bearing capacity and deflection of the I-joists were calculated.Compared with the experimental values,a flange joint and a web joint were proposed.The design method of the I-joists are given.