Test Setup Design and Cyclic Evaluation of Rocking CLT Wall and Floor Restoring Force Lateral System is a well-researched Engineering Thesis/Dissertation topic, it is to be used as a guide or framework for your Academic Research.
The introduction of the demand for mass timber buildings are with seismic hazard areas has called for new lateral systems. Lateral systems in mass timber building typically utilize a rocking shear wall with post-tensioned rods to provide system re-centering. These post-tensioned rods add axial load to the shear wall and potentially endure long term creep affects.
Mass Timber buildings consist of cross-laminated (CLT) shear walls and floor slabs along with glulam beams. The flexural capacity of the CLT floor slabs along with the dead load can provide an alternative source for the restoring force. This project developed a test setup to accommodate full-scale cyclic testing of this restoring force.
Cyclic testing included determining the influence of dead load on the system and the influence of ductile hold-downs. Hold-downs properties can be varied to alter the shape of the hysteretic curve and to allow re-centering. The hold-downs will serve as sacrificial fuses with the goal all yielding occurs to them while mass timber members remain elastic.
The demand for quick construction methods and utilizing more sustainable building materials can be met with mass timber, including the utilization of cross-laminated timber (CLT). The challenge is to develop building structural systems that also achieve high levels of performance under design level earthquake demands.
The focus of this project is on buildings with mass timber structural cores, which often contain stairs or elevators and are the primary lateral load resisting system for the building. Recent developments in rocking CLT shear walls have utilized steel rods to re-center the structure following a seismic event. For reasons of economy and for limiting material creep, this project is developing rocking core walls that utilize floor flexural stiffness and dead load rather than post
Rocking behavior along with ductile hold-downs allows for system re-centering and targeted damage to ductile fuses. The rocking wall has an elastic section of its hysterics with a stiffness change as the wall begins to rock as seen in Fig. 1. Ductile hold-down’s hysteric is a typical steel yielding behavior with an elastic and post-yield stiffness.
The combination of these two creates a flagging behavior of the system’s hysteretic behavior. Flagging depth can be defined as the percentage from the first yield to the return of the elastic stiffness line, this value is defined as beta (β) (Fig. 1). Rocking wall behavior and ductile behavior have a beta value of zero and one, respectively. This bounds all test results between zero and two, beta values of less than one are self-centering while values greater than one will have residual drifts.