Study On The Mechanism Of The Masonry-timber Historic Building Suffering Force

There are many historic buildings in Tianjin, so it is a long way to figure out how to protect those meaningful buildings well. The paper makes a good effort at the mechanism of the masonry-timber historic building suffering force, especially the dynamic characteristics. Dynamic characteristics calculation and test is done to find out the law of its variation, the factors that affect the variation and the methods of its calculation. The work done here is wished to do some help to the aspects of the numerical analysis and the reinforcement of the masonry-timber historic buildings.The wood floor is the main characteristic that tells the masonry-timber buildings from the concrete ones. It is discussed how the variations of its stiffness affect the natural frequencies. It is displayed that the stiffer floor can lower the natural frequencies of the building, enhance the resistance of the building to the contortion and improve the ability to suffering force as a whole of the building. The dynamic characteristics of a typical masonry-timber historic building with a timber roof truss and arch dome is calculated and tested. The results support that the arch dome can well transfer the horizontal loads, and the simulation of the roof is also discussed. The modal analysis of two classic masonry-timber historic buildings is carried out.The results show some regular patterns of its dynamic characteristics: the first and the second translational mode shapes didn't appear at the directions along the boundaries of the buildings as expected but at the directions that had a angle with the boundaries of the buildings; and it seems that relation exists among the natural frequencies in different directions.The elastic Time History Analysis is done to a typical masonry-timber historic building, while another model, which is almost as same as the calculated one except for its floor that is made by the concrete instead of the wood, is also done the same Time History Analysis. The two results are compared with as to find the different reactions of those two types of buildings under the same dynamic loads. At last, the errors are discussed when the natural frequencies of the historic masonry buildings are calculated by the lumped-mass method.