Thesis
Temperature and time dependent behaviors of a wood-polypropylene composite
Washington State University
Master of Science (MS), Washington State University
2006
Handle:
https://hdl.handle.net/2376/542
Abstract
Wood-plastic composites (WPCs) are poised to become a viable alternative to traditional civil engineering building materials in select structurally-demanding capacities. The main impediment to utilizing these materials as structural members is the lack of performance data in adverse conditions. The two conditions investigated in this study are: the static performance in tension and compression at elevated temperatures and the long-term creep behavior in tension and compression of a polypropylene-pine WPC at a full allowable design stress via accelerated testing. The first interest for this study was the static tensile and compressive strength, stiffness, and straining behaviors at elevated temperatures. Inverse relationships for ultimate strength and stiffness were found, while a direct relationship for maximum strain was observed. An analysis to determine the nonlinear constitutive relations was conducted; showing appropriate stress strain behavior for tension and compression can be interpolated for any likely temperature service condition. Furthermore, a method to assess and implement design reduction factors consistent with timber design methodologies is recommended based upon the performance of the specimens at different temperature levels. The second focus of this work was to evaluate the creep performance of this formulation and to assess the validity of using temperature as the accelerant for an accelerated testing procedure (TTSP). The short-term creep behavior is modeled using Findley's power law. Appropriate short-term creep parameters were determined from the model parameter trends. The short-term tests are then combined to generate master curves in tension and compression for a maximum allowable design load case of 40% of ultimate load at 21.1°C. The predictive capability of these master curves was 5.7-years in tension and 2.7-years in compression. Temperature was proven to be a more efficient variable for generation of accelerated test data than previous studies which used stress.
Metrics
6 File views/ downloads
30 Record Views
Details
- Title
- Temperature and time dependent behaviors of a wood-polypropylene composite
- Creators
- Andrew Joseph Schildmeyer
- Contributors
- Michael P. Wolcott (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525136201842
- Language
- English
- Resource Type
- Thesis