To protect Chinese ancient building

by theoretical calculation and finite element simulation

the cause of sinkage and the strengthening method of tenon-mortise joint of the face beam in the 3rd part of Taihe Palace in the Forbidden City were studied.Two strengthening methods were considered

by which the calculation diagrams and the finite element models for the beam were built and the static analysis was carried out.Based on the analysis results

displacement and stress distributions of the face beam before strengthening were obtained.Based on the laws of cultural relics protection

two strengthening methods were discussed and the more suitable one was selected.Results show that the main cause of sinkage of the face beam tenon relates closely to the over great values of bending

tension and shear stresses at the tenon-mortise joint position.The method that strengthens tenon-mortise joint by additional columns under the face beam may bring adverse effects to the substructure

However

the method of using steel-wood composite system to strengthen the joint is more suitable

which meets the demand of cultural relics protection.