Wood fiber-reinforced recycled plastic composites (WRPCs) manufactured from sawdust and post-consumer high density polyethylene (HDPE) were studied in this article. The thermal, flexural properties and impact strength of the manufactured WRPCs were determined according to the relevant standard specifications. Effects of mix ratio, wood fiber length, type, and content of coupling agent on the mechanical properties of WRPCs were investigated. The fracture surfaces of WRPCs after impact test were examined and the fracture mechanism of WRPCs due to impact was also analyzed in this article. The results indicated that incorporation of wood fibers resulted in higher melting and slower crystallization rate of WRPCs. A linear relationship between cooling rate and crystallization rate was observed. With the increasing of the wood fiber weight fraction, the flexural strength of WRPCs increases. The longer the wood fiber length, the less the flexural strength of WRPCs under the conditions of this study. The Charpy impact strength decreases with the increasing of wood fibers content in WRPCs. It appears that the optimum compatibilizer content for wood and recycled HDPE mixing is 5% in weight fraction.
In an arch dam, adjacent monoliths separated by vertical contraction joints may move relative to each other during an earthquake, resulting in the gradual opening and closing and possible shear movement at the joint surfaces. This paper presents the formulation of a joint constitutive model for a zero-thickness joint element that can simulate both the opening and closing and shear sliding behaviour, as well as the non-linear shear key e ects of the joint. The proposed joint element has been implemented in the concrete arch dam ÿnite element analysis program ADAP-88. The response of a typical arch dam subjected to earthquake ground motion is presented to demonstrate the capability of the proposed joint model. Results from a parametric study carried out to study the sensitivity of the response to the joint properties are discussed. The joint parameters considered in the parametric study include apparent cohesion, friction coe cient, and whether the joint has beveled or unbeveled shear key, or the joint is unrestrained in shear sliding. The analysis results show that joint opening and shear slippage at the contraction joints can have signiÿcant e ects on the response of an arch dam. ? 1998 John Wiley & Sons, Ltd.
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