J. Daniel Dolan

Development of Nailed Wood Joint Element in ABAQUS

Testing showed that the hysteretic behavior of nailed wood joints governs the response of many wood systems when subjected to lateral loadings. Unfortunately, commercially available software does not have the appropriate hysteretic element for a nailed wood joint, and the accuracy and versatility of the previously developed nail joint elements are not satisfactory. A general hysteretic model, Bouc-Wen-Barer-Wen, was modified to represent the hysteretic behavior of a nailed joint, in which the hysteretic constitutive law is characterized by a series of ordinary differential equations. It can produce versatile and smoothly varying hysteresis curves, is nonlinear, history dependent, and includes stiffness and strength degradation, and pinching. Based on the test data, the suitable parameters for different joint configurations can be estimated through genetic algorithms. This model was embedded in commercially available software, ABAQUS/Standard (Version 6.5), as a user-defined element which accounted for the coupling property of the nail joint action. A detailed shear wall was modeled and analyzed, and the results agreed well with the test data.

Development of a Wood-Frame Shear Wall Model in ABAQUS

After modifications, the Bouc-Wen-Barber-Wen (BWBN) model was used in simulating the hysteretic behavior of wood light-frame shear walls. A complete shear wall model is composed of boundary framing members and two-diagonal modified BWBN hysteretic springs. The parameters of the springs can be estimated based on the shear wall test data or detailed shear wall simulation results. To verify the accuracy and efficiency of this shear wall model, a two-story residential building was simulated and a three-dimensional dynamic analysis was conducted on it. The resultant structural responses agreed with the test results well.

Performance of Log Shear Walls Subjected to Monotonic and Reverse-Cyclic Loading

Low-rise buildings are typically designed with shear walls and horizontal diaphragms to resist lateral load during windstorms and earthquakes. Although seismic performance and lateral load resistance behavior are generally well-understood for light-frame wood construction, this is not true for log construction. Research is needed to characterize log shear wall behavior subject to racking loads, and to develop recommendations for designing log walls to resist lateral loads from seismic or wind events. Monotonic and reverse-cyclic tests were conducted on log shear walls with 1:1, 2:1, and 4:1 aspect ratios. These walls showed higher resistance than conventional light-frame shear walls and similar hysteretic behavior to concrete and masonry shear walls. Log walls withstood large in-plane displacements without significant load reduction using lateral bracing typical of that used for light-frame wall testing; however, the test procedure would be improved by providing full-wall support to resist out-of-plane displacements of log shear walls. Design recommendations were developed based on the experiments reported herein.

Experimental Investigation of Self-Centering Cross-Laminated Timber Walls

AbstractMass timber is an attractive and sustainable alternative structural engineering material to concrete and steel. Despite successful midrise to high-rise timber building projects around the w...

Deck and Porch Floor Lateral Loading by Occupants

AbstractTwo deck floors, with different lateral stiffnesses, were constructed to measure lateral loads generated by occupants that are needed for design of residential or commercial exterior deck-type floors. Load was measured with two load cells attached at each end of the ledger representing the attachment to the building. The decks were supported on rollers, simulating minimal lateral resistance from columns. Occupants performed two different types of dynamic actions, in two orthogonal directions, at occupancy live load levels of 0.48, 0.96, 1.44, and 1.92 kPa (10, 20, 30, and 40 psf). The first loading cyclic was a side-to-side swaying motion that could result from a deliberate synchronized movement such as dancing. The second was an impulse-type load, which simulated horseplay-type activities. The difference in stiffness between the two decks resulted in a significant change in the human–structure interaction. Significant inertial effects were observed when the flexible deck was loaded parallel to th...

Lateral Load Path and Capacity of Exterior Decks

AbstractExterior decks must be designed to resist all applicable load cases. Vertical (gravity) loads are well defined, but less is known about designing decks for lateral loading. The focus of this study was to better understand the ultimate strength and load paths of two common deck constructions subjected to monotonic lateral loading. A portion of a conventional light-frame wood-floor diaphragm was built, to which the decks were attached. One deck was constructed with a lateral hold-down tension connector and the other deck had no hold-down tension connector. The lateral resistance and load path of each deck were investigated by applying a monotonic force through the centroid of the deck surface. The ledger board was connected to the house rim board with lag screws. Forces in each lag screw and hold-down connecting the deck to the diaphragm were recorded. Preliminary tests revealed a weakness in the deck joist–to–deck ledger connection; this was resolved by using joist hangers that featured a perpendic...

Potential Use of Deformed Shank Nails as a Solution to Annoying Vibrations in Wood Floor Systems

Abstract In the United States, modern designs of wood floor systems rarely directly account for annoying floor vibration criteria, because it is not a required design criterion in the International...