Effective Strengthening of Timber Beams: Experimental Investigation

Abstract

This paper presents an experimental study on the strengthening of rectangular timber beams under monotonic loading. Both flexural and shear behavior of the specimens was studied. A total of five timber beam specimens with identical cross-sections were prepared. The first three specimens had a long span (3 m), whereas the remaining two had a short span (1 m). In order to obtain the benchmark parameters for flexural and shear behavior, one beam specimen from each span group was tested without adopting any strengthening measures. The long beam specimens were tested under four-point loading (for flexure) and the short ones under three-point loading (for shear). One of the long beam specimens was strengthened with mild steel plates bolted on the tension and compression sides. The last long beam specimen was strengthened with a carbon fiber reinforced polymer (CFRP) laminate adequately bonded on the tension side only. The other short beam specimen was strengthened with self-tapping screws in different detailing arrangements on the tension and compression sides to strengthen the specimen against horizontal shear. The performance assessment of all specimens was done on the basis of their peak load resisted, load versus midspan displacement, stiffness response, and failure mode. Last, the theoretical strengths of the specimens were quantified and were compared with the strengths obtained during the tests. It was observed that all strengthening measures adopted improved the targeted flexural and shear performance of the beam specimens. However, the performance improvement achieved was proportional to the cost involved for each strengthening measure adopted.