On the Use of Finite Element Method and LEFM to Assess Bearing Capacity of Historic Notched Timber Beams at Arbitrary Location

Abstract

As notched beams are often and commonly found in historic structures, the assessment of potential bearing capacity is of utmost importance. In practice a few equations are found in the standards dealing with the problem, nevertheless, common use is only on tension side near the ends of the beams. To fill the gap and also allow for computing the critical force of arbitrary notched beam under arbitrary loads the authors use energy-based approach along with FEM. The idea is based on simple virtual crack closure technique and calculation of the work consumed by the crack to grow. Such a method is able to assess the bearing capacity of the whole beam. This procedure allows for a detailed analysis of the problem in real structure. The method described above is documented in the paper and a numerical model is constructed in ANSYS. The assessed values are compared to experimental work on real timber beams. Experimental work consisted of testing 9 beams (softwood; Norway spruce) with dimensions 0.2 × 0.25 × 5.9 m, a cut in the central part of the beam and 4-point bending load scenario. The numerical analysis is able to assess the critical load relatively well. Results are critically evaluated and drawbacks are discussed in-depth.