Flexural and creep strengthening for wood/PVC composite members using flat bar strips

Abstract

This paper presents the flexural and creep performances of the strengthened wood/poly(vinyl chloride) (WPVC) composite members by using various types of flat bar strips adhered to the tension side. The WPVC composite member used was produced by an industrial-scale twin-screw extruder using the weight ratio of the wood to PVC compound of 1:1. High carbon steel (HCS) flat bar was selected a suitable material for the strengthening of WPVC composite members because of its high tensile stress, thin and light weight. For tension failure control, the flexural properties of strengthened WPVC composite member were improved with thickness and number of HCS strip used. By using one strip of HCS with 0.5 mm thickness adhered in tension side of WPVC composite member, the ultimate loads increased significantly up to 64% and 101% under flat-wise and edge-wise loading directions, respectively. Moreover, the strengthening of WPVC by using the HCS flat bar could reduce significantly the creep behavior, especially in edge-wise direction. Due to the same sustained load, the creep displacements of the strengthening WPVC composite members reduced significantly for 48% under flat-wise direction, and 11% under edge-wise loading direction. The creep displacement per sustained load and fraction deflection was found to reduce significantly by the HCS strengthening method.