Opcije pristupačnosti Pristupačnost
Seismic behaviour of multi-storey buildings

Enhancing the resilience of the built environment is an important challenge around the globe. As far as the seismic hazard is concerned, significant results have been achieved in the last decades. Recent events have highlighted that social, economic and environmental consequences in urban areas hit by earthquakes are still very high. The need of taking into proper account the damage mitigation together with the collapse prevention in seismic engineering is one of the goals of future development of structural engineering.

If sustainably sourced, timber is undoubtedly one of the most environmentally-friendly materials currently available, being a natural carbon sink and truly renewable. This has made timber a popular material among sustainability champions and protagonists of green construction. If sustainably sourced, using timber can have an additional positive environmental impact because trees absorb carbon dioxide through photosynthesis and lock it away as carbon, thus removing it from the atmosphere. In addition, the manufacture of wood products requires less fossil fuel than non-wood alternative building materials such as concrete, metals, or plastics.

The EU forest-based industries constitute one of Europe's largest industrial sectors, accounting for around 10% of European manufacturing industry's total value of production, value-added and employment. They provide employment and income for some 2.6 million people directly all over the EU, in particular in remote areas. The EU major objectives in relation to forestry are increasing  the  use  of  sustainably-produced wood,  as  environmentally-friendly  and  climate  neutral  sources of  materials  and  energy. The European Environment Agency is driving a more integrated approach to employment strategies that support the development of skills, jobs and training related to the needs of the green technology industry including timber – Croatia can greatly benefit from this. 47% of Croatian land territory is covered by forests and there is a huge potential for new industries and development of new skills and jobs regarding the usage of timber not only in furniture sector but also in construction sector. Clear market opportunities are visible regarding the tradition of timber in Croatia, position and access to the key centers of excellence in Europe (Austria, Germany, Italy). One of materials of future is cross-laminated timber (CLT).

In the 20 years since its invention, CLT has become a widely used construction material. CLT is comparable and, in some aspects superior, to concrete or steel. CLT possesses numerous advantages as a construction material, including its superior structural and environmental performance, as well as the speed and efficiency with which CLT buildings can be erected. Research and building code development have proven that timber components, assemblies and entire structures are capable of meeting or exceeding the most demanding earthquake and seismic design requirements. Wood products and systems give designers and engineers a readily available and robust selection of code-approved building materials that can help commercial and residential buildings and other infrastructure better withstand seismic events.

The seismic performance of a URM building is largely determined by the quality of the connections between the external URM walls and the flexibility of the internal timber diaphragm. These connections often consist of steel anchors, which are also used to restrain features such as parapets. The brittle nature of the URM walls means that, if they are overloaded, they will collapse, and the support for the floors and roof is lost. Securing parapets and façades to the main building fabric will significantly improve the seismic performance of these features but is not a substitute for strengthening of the overall structure of a URM building. However, securing techniques can significantly improve the seismic performance of these features. Various method for improvement of these kind of structures exists. Fiber reinforced polymer (FRP) materials offer viable solutions to solve or lessen the effects of overloading. FRP  materials  in  the  form  of  laminates  and rods  are  available  for  the  strengthening  of  masonry elements.  Commonly three types of fibers are used, carbon, glass and aramid.  The use of laminates involves the application (i.e. external adhesion) of fiber sheets by manual lay-up to the  surface of the  member  being  strengthened. Investigations have shown that for walls subjected to in-plane loads, the shear capacity  of the walls was notably   enhanced when strengthened with FRP laminates. Present knowledge in the field of masonry structures lacks comprehensive state-of-the-art techniques and procedures. In addition, guidelines and norms for retrofitting of such structures are still in development. In this project focus will be set on strengthening existing masonry structures with FRP and/or CLT.

Current design approaches in building codes around the world, e.g., Eurocode (EC8), NBCC, ASCE-7 follow force-based design methods. At the moment just a few norms exists for existing structures and future development in seismic research is pointed a lot in this direction. Nevertheless, timber as a structural material is very little represented in the norms, i.e. EC8 have only four pages related to timber structures. The revision process of the structural Eurocodes and therefore of EC8 began in 2015 and the final updated version is expected to be released around 2020.

This project aims at elaborating a new and comprehensive scientific and technical framework for the analysis, design and risk mitigation of structures under earthquakes.