TRADITIONAL TIMBER JOINERY: A MODERN ANALYSIS (MORTISE & TENON, SEMI-RIGID CONNECTIONS, FINITE ELEMENT-WOOD, KNEE BRACE EFFECTIVENESS)

Many thousands of heavy timber structures built years ago still exist today. In them, the individual members are connected with pegged, mortise and tenon joinery. A recent rebirth of this technique is seeing hundreds of new joinery-connected buildings being constructed each year. However, to date almost no structural analysis employing modern approaches has been performed on this complex, centuries-old technology. This dissertation undertakes that task.;The research reported here consists of two test programs each matched with computer analyses of joinery-connected structures. Testing was of full-size timber frame bents subjected to racking and gravity loads. Computer analysis of the bents employed a linear, plane-frame program which included a three-spring model of the mortise and tenon connections. The axial, shear, and moment spring constants for the connection model were obtained through tests on full-size, double-pegged, mortise and tenon connections. In addition, a finite element modeling of the connections matched the connection tests. The finite element model was also used to investigate the effects on connection behavior when certain details were varied.;The computer analysis of the bents agreed well with the bent tests. Except for the knee brace connections' axial modulus, connection stiffnesses had only secondary influence on the analytical results. The connection tests showed that the pegs and mortises failed before the tenons. Comparing the analytical connection forces under service loads with the connection test results indicates a minimum safety factor of three against connection failure. A significant finding of the finite element analysis was that increasing the peg diameter is the most effective way to increase the mortise and tenon connection's strength and stiffness.;This research represents an exploratory effort to apply modern structural analysis to traditionally connected heavy timber structures. Two important contributions are (1) a sensible procedure for analyzing such structures to determine if their design and construction are reliable and safe and (2) recommendations on how the methods can be improved and the objectives expanded in future research.