Theme T4, dedicated to "Civil Engineering Projects", covered a wide spectrum of various structures. Most of them require a specific approach in order to allow them to withstand seismic action.

This is why it was felt necessary to divide this theme into sub-themes dealing with particular types of structures. Obviously, buildings and bridges constitute clear-cut categories with specific requirements. But there are many other types of structures of which the behaviour under seismic loads should be deepened. This includes dams, tunnels, nuclear, hydraulic and thermal power plants, offshore platforms, large LNG tanks and more generally structures interacting with the soil. These structures were placed into a general sub-theme, named Special Structures.

The choice of papers to be presented orally during the sessions was difficult since numerous papers were received, dealing with Civil Engineering Projects. A severe selection was made, in order to give a sufficient time for each oral presentation and to avoid a quick and superficial browsing of their content. Of course, papers not presented orally were presented on posters and have their own merits, and proceedings should be also considered for full information.

Special structures

Dr. Kolias from Greece and Dr. Cherezy from France chaired this session. Two topics appeared to outnumber other subjects in the received papers: dams and tunnels with their interaction with soil. They were the main topics of this session with nine presentations.

Some statements were drawn from these papers:

• analysis of soil-structure composites, such as dams and tunnels or cut-and-cover built structures, should be performed in 3D;
• as emphasised by Dr. Darbre, "modelling must be adapted to physical reality and not to available computer programs".

Bridges

MM. R. Lacroix and D. Amir Mazaheri from France chaired this session. Nine authors examined the effect of seismic actions upon classical bridges and upon cable-stayed bridges and their piers. Some conclusions may be drawn from these papers:

1. RC bridges designed according to EC8 part 2 performed satisfactorily in pseudo-dynamic tests;
2. Seismic design of cables in cable-stayed bridges should still be deepened;
3. The behaviour of long multi-span bridges and their piers is not yet fully understood;
4. The importance of the effects of hydrodynamic added masses in submerged structures withstanding earthquakes should not be underestimated.

Buildings

Prof. J. Bouwkamp from Germany and Dr. M. Kahan, from France chaired this session. After a presentation of fifteen papers by M. Kahan, the session was first dedicated to the posters exhibition, and finally concluded by an open discussion among participants.

The papers were classified under six items: experimental works, analytical developments, comparison between analytical and experimental results, design, practical examples and retrofitting.

Conclusions

Very interesting contributions have been brought to this theme dedicated to "Civil Engineering Projects". I would like to put an emphasis on needs of civil engineers. It seems that there is a law according to which the more important the structure is, the more stringent the seismic actions are, whatever the seismic data concerning the site where the structure is going to be built is.

On the other hand, it becomes less and less acceptable that people living in buildings and small houses suffer from earthquakes.

Both issues mean that civil engineers will have to deal more and more with seismic design. We, specialists in this field, have to give them ways and means to do it in order to attain the required level of safety against seismic hazards.

Reported by L. Pliskin