Abstract:The paper presents an analysis and a subsequent refurbishment of significant buildings in Slovakia. The analysis focuses on the load-bearing timber roof-structures. There are three sacral objects and one long-span sporting hall presented. The paper tries to introduce the background of difficult refurbishment process. Before the refurbishment, a thorough process of investigation is required. This process includes four basic steps. General information about the load-bearing structure is obtained from the geodetic survey that foregoes the process of diagnostic inspection. The diagnostic survey focuses on the defects of the structure, their degree and possible origin. Modern methods of computer modelling help to understand the structural operation and help to find reserves of carrying capacity. Structural analysis should take into account all detected defects and the joint types, which can influence the transfer of forces. The refurbishment project is usually a brief, but clear summary for fulfilling the needs of Monument Board and building process. All the steps require knowledge from different fields and require professional approach.

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Consideration the semi-rigid behaviour of connections is an essential part of the modern way of the design of timber load-bearing structures. The computational models using the finite element method allow us to easily replace the use hinge operation with the appropriate stiffnesses of connections in the design. Taking the stiffness of the joint into consideration can have a significant influence on the load distribution and on the stiffness of the object as a whole. The paper contains the calculation process of the stiffness of selected connections. The mentioned stiffnesses could be used in modelling of timber load-bearing structures.

The paper presents results of exceptional experimentation, which focuses on the long-term loading of timber beams. The uniqueness of the research is given by real dimensions of samples and by the term of loading over one year. In the frame of investigation four currently often used timber girders had been investigated. The aim was to observe the time dependence of deflections over time. According to deflection curves the approximations for simulating the final deflection at the end of structure’s lifetime had been defined. The obtained creep coefficients were compared with the values listed in the valid standards.

Timber beams subjected to long - term loadingWood is a significant structural material, which is often used for timber bearing structures. Elements of timber structures must especially satisfy safety requirements, which are expressed by the ultimate limit states in the established standards. The structure must also satisfy the serviceability limit states. Local and global deformations make it impossible for the structure to serve the purpose it was designed for. It is important to take the deflections and their possible increase into account in the design to provide a structure which can be used during the whole period of service. Based on earlier examinations, it is known that a timber element over the course of long-term loading shows creep behavior. The structure of wood is able to adapt to the conditions of the surrounding environment. The properties of wood are especially affected by the relative humidity of the air and then by the type, intensity and duration of the loading. The most important factors affecting the serviceability of timber structures are volume changes caused by humidity and additional deflections caused by the effects of long-term loading. These phenomena emphasize the importance of serviceability limit states for timber structures. The paper deals with a long-term experimental investigation of timber girders that are currently often used. The aim was to obtain the deflection curves and mark the time dependence and the final deflections. The paper will also define the approximations for simulating the time-dependent deflections and obtain the creep coefficients for calculating the final deflections of the girders investigated.