Marco Lo Ricco | University of Wisconsin Milwaukee (original) (raw)
Address: Milwaukee, Wisconsin, United States
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Cross-Laminated Timber (CLT) garners international interest with increasingly taller wood structu... more Cross-Laminated Timber (CLT) garners international interest with increasingly taller wood structures built of robust, rigid panels. For seismic resilience of multistory platform construction, this study prototypes a CLT rocking wall system with an elliptical boundary profile. Curvilinear cuts to the load-bearing edges of a rectangular CLT panel produce smoother lateral response to earthquakes, with gravity-driven passive re-centering ability and reduced crushing damage at wall corners. Stiffness and ductility of the rocking wall can be tuned by proportioning the ellipse profile. Connections between the rocking wall and diaphragm can be designed to transfer shear and influence rocking behavior. This paper presents the design and full scale cyclic testing performance of a prototype CLT rocking wall with two different types of connections. Hysteresis plots of the test results and idealized analytical models show good agreement between design assumptions and actual properties of the pen...
While research of Cross-Laminated Timber (CLT) structures prioritizes force-based design for eart... more While research of Cross-Laminated Timber (CLT) structures prioritizes force-based design for earthquake hazards, this project navigates a complementary displacement-based route—charted by United States building code provisions for seismic isolation. Curvilinear cuts to the load-bearing edges of stock CLT panels enable walls to roll through pendulum motion. Elliptical geometry provides the mechanism to lift supported storeys, passively self-centre through oscillatory damping, and avert damage to the panel corners. Wider elliptical profiles reliably negate residual displacements, as a consequence of greater eccentricity between the contact forces. Panels shaped to lesser elliptical eccentricities, however, isolate superstructures more effectively by lengthening the rocking period as much as 1.5 seconds and adding greater than a metre of lateral displacement capacity. Physical models at 1/12 scale, computer simulations, and tests of the contact behaviour between CLT panel edges and bou...
Science
Description Turning wood into honeycombs Wood is an attractive material for structural applicatio... more Description Turning wood into honeycombs Wood is an attractive material for structural applications, but it usually works best as boards or sheets. Xiao et al. have developed a process for engineering hardwood that allows these sheets to be manipulated into complex structures (see the Perspective by Tajvidi and Gardner). The key is to manipulate the cell wall structure by shrinking and blasting open the fibers and vessels by drying and “water-shocking” them. This process creates a window wherein the wood can be manipulated without ripping or tearing. Honeycomb, corrugated, or other complex structures are locked in once the wood dries. —BG Closing and reopening the vessels and fibers in hardwood allows it to be molded into complex shapes. Wood is a sustainable structural material, but it cannot be easily shaped while maintaining its mechanical properties. We report a processing strategy that uses cell wall engineering to shape flat sheets of hardwood into versatile three-dimensional (3D) structures. After breaking down wood’s lignin component and closing the vessels and fibers by evaporating water, we partially re-swell the wood in a rapid water-shock process that selectively opens the vessels. This forms a distinct wrinkled cell wall structure that allows the material to be folded and molded into desired shapes. The resulting 3D-molded wood is six times stronger than the starting wood and comparable to widely used lightweight materials such as aluminum alloys. This approach widens wood’s potential as a structural material, with lower environmental impact for buildings and transportation applications.
Cross-Laminated Timber (CLT) garners international interest with increasingly taller wood structu... more Cross-Laminated Timber (CLT) garners international interest with increasingly taller wood structures built of robust, rigid panels. For seismic resilience of multistory platform construction, this study prototypes a CLT rocking wall system with an elliptical boundary profile. Curvilinear cuts to the load-bearing edges of a rectangular CLT panel produce smoother lateral response to earthquakes, with gravity-driven passive re-centering ability and reduced crushing damage at wall corners. Stiffness and ductility of the rocking wall can be tuned by proportioning the ellipse profile. Connections between the rocking wall and diaphragm can be designed to transfer shear and influence rocking behavior. This paper presents the design and full scale cyclic testing performance of a prototype CLT rocking wall with two different types of connections. Hysteresis plots of the test results and idealized analytical models show good agreement between design assumptions and actual properties of the pen...
While research of Cross-Laminated Timber (CLT) structures prioritizes force-based design for eart... more While research of Cross-Laminated Timber (CLT) structures prioritizes force-based design for earthquake hazards, this project navigates a complementary displacement-based route—charted by United States building code provisions for seismic isolation. Curvilinear cuts to the load-bearing edges of stock CLT panels enable walls to roll through pendulum motion. Elliptical geometry provides the mechanism to lift supported storeys, passively self-centre through oscillatory damping, and avert damage to the panel corners. Wider elliptical profiles reliably negate residual displacements, as a consequence of greater eccentricity between the contact forces. Panels shaped to lesser elliptical eccentricities, however, isolate superstructures more effectively by lengthening the rocking period as much as 1.5 seconds and adding greater than a metre of lateral displacement capacity. Physical models at 1/12 scale, computer simulations, and tests of the contact behaviour between CLT panel edges and bou...
Science
Description Turning wood into honeycombs Wood is an attractive material for structural applicatio... more Description Turning wood into honeycombs Wood is an attractive material for structural applications, but it usually works best as boards or sheets. Xiao et al. have developed a process for engineering hardwood that allows these sheets to be manipulated into complex structures (see the Perspective by Tajvidi and Gardner). The key is to manipulate the cell wall structure by shrinking and blasting open the fibers and vessels by drying and “water-shocking” them. This process creates a window wherein the wood can be manipulated without ripping or tearing. Honeycomb, corrugated, or other complex structures are locked in once the wood dries. —BG Closing and reopening the vessels and fibers in hardwood allows it to be molded into complex shapes. Wood is a sustainable structural material, but it cannot be easily shaped while maintaining its mechanical properties. We report a processing strategy that uses cell wall engineering to shape flat sheets of hardwood into versatile three-dimensional (3D) structures. After breaking down wood’s lignin component and closing the vessels and fibers by evaporating water, we partially re-swell the wood in a rapid water-shock process that selectively opens the vessels. This forms a distinct wrinkled cell wall structure that allows the material to be folded and molded into desired shapes. The resulting 3D-molded wood is six times stronger than the starting wood and comparable to widely used lightweight materials such as aluminum alloys. This approach widens wood’s potential as a structural material, with lower environmental impact for buildings and transportation applications.