Simulated Response of Degrading Hysteretic Joints With Slack Behavior

A novel, general, numerical model is described that is capable of predicting the load-displacement relationship up to and at failure of multiple-bolt joints in timber of various configurations. The model is not tied to a single input function and bolt holes are permitted to be drilled oversize resulting in a slack system. The model consists of five parts. A new mathematical hysteresis model describes the stiffness of the individual bolt at each time step increment and accounts for non-linear and slack behavior; a mechanically-based structural stiffness model explains the interaction of one bolt with another bolt within a joint; an analytically-based failure model computes the stresses at each time step and initiates failure if crack length equals fastener spacing; a stochastic routine accounts for material property variation; and a heuristic optimization routine estimates the parameters needed. The core model is a modified array of differential equations whose solution describes accurate hysteresis shapes for slack systems. Hysteresis parameter identification is carried out by a genetic algorithm routine that searches for the best-fit parameters following evolutionary principles (survival of the fittest). The structural model is a linear spring model. Failure is predicted based on a newly developed 'Displaced-Volume-Method' in conjunction with beam on elastic foundation theory, elastic theory, and a modified Tsai-Wu Failure criterion. The devised computer model enhances the understanding of the mechanics of multiple-bolt joints in timber, and yields valid predictions of joint response of two-member multiple-bolt joints. This research represents a significant step towards the simulation of structural wood components.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Wood Science and Forest Products

Department dc:contributor.department

Wood Science and Forest Products

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2001

Author dc:creator

• Heine, Christian P.

Chair dc:contributor.committeechair

• Dolan, James Daniel

Committee members dc:contributor.committeemember

• Plaut, Raymond H.
• Singh, Mahendra P.
• Woeste, Frank E.
• Loferski, Joseph R.

• brittle failure
• hysteresis model
• slack systems
• genetic algorithm
• multiple bolts
• dynamic

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-08092001-100756

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/28576