A "Damage distribution" based on the field observations made on the days between June 28 and July 3 1998 has been drawn on the MAP. The region where the damage of the earthquake were maximum, a kind of epicenter region, lies between the Aptioðlu Village in the southwest and the Büyük Mangit Village and Ceyhan City in the northeast. In this region Misis, Suluca and Geçitli Towns, Industrial Park of Adana are located. Another region indicated on the Map includes the area where damage to the minarets of the mosques was observed. Minarets are typical structures: their structural materials, heights and diameters are almost standard. Their similar characteristics and damage levels could be used to identify the intensity of the earthquake at that location. Minarets are high and slender structures and therefore have "long" periods of vibration. The soft alluvial ground of the Çukurova plain has a long natural period of vibration and the long periods of vibration of the minarets increase the probability of resonance to occur for these structures. Minarets within the earthquake felt zone exhibit various levels of damage. Besides, the regions where minarets were not effected can be distinguished.

This bridge of Adana-Gaziantep Highway is on the river Ceyhan (Picture-1). It is very close to Ceyhan City. Damage due to collision of bridge decks (Picture-2) and lateral displacement of the first and the last bridge deck on the lane towards Adana can be seen on (Picture-3) and (Picture-4) Damage on the beams connecting the bridge piers of the two throughways of the bridge are observed (Picture-5).

Approximately 1 km away from the western end of this bridge, parallel cracks of a few hundred meters long in the east-west direction and settlements are observed on the road fill (Picture-6). This part of the road fill is only 50-70 meters away from the Ceyhan river flowing westward. There is a sand and gravel quarry by the river at this point. Sand blows indicating liquefaction on the riverbanks at this point can be observed.

A viaduct on the Adana-Gaziantep Expressway again on the Ceyhan River located about 5-6 kilometers southwest of the bridge mentioned in the above paragraph were also effected from the earthquake. Collion of the bridge decks in the road direction as observed in the parapet walls of the bridge decks (Picture-7),(Picture-8),(Picture-9) and there is also evidence of strong shaking of the bridge piers and the decks perpendicular to the direction of the road (Pictures-10),(Picture-11) The teethes of metal at the joints of the decks were broken. The broken metal pieces were found as far 50 meters away from the point where decks meet.

This is an historical stone arch bridge and according to the Bridges Book of the General Directorate of Highways it had been constructed in IV Century AC (Picture-12). Total length is 132.70 meters and width is 6.50 meters. It has nine spans. The largest span is 11.00 meters. During the earthquake on the top of the bridge the crack seen on (Picture-13) occurred. Underneath the arch at this point a wide crack in the bridge axis also occurred. The width of the crack was about 5-10 cm. In the mid point of the bridge at the top of the arch a separation crack can be observed (Picture-14). In (Picture-15) a cracked piece of stone on the parapet wall of the bridge can be observed.

Filler walls of the reinforced concrete buildings of the region are made from lightweight concrete blocks. The compressive strengths of these blocks are very low. These filler walls usually failed in a way as shown in (Picture-16). While filler walls, within reinforced concrete frames, made from hollow clay bricks fail in well-pronounced X-shaped shear cracks‘ these walls made from hollow concrete blocks failed in shear with horizontal cracks.

Collapse of high gable walls were observed in the "old" parts of City, Residential block of the Hospital of the Social Insurance Establishment (Picture-17), Police Department (Picture-18), Telecommunication Building (Picture-19). (Picture-20) shows a collapsed parapet wall. External walls of the new municipal building which was under construction at the time of the earthquake fell down to the street. This building had eight stories with a story height of more than 4.00 meters and filler block joist floor system with shallow beams (Picture-21), (Picture-22). (Picture-23) shows the damage to an external filler wall not bounded by the frame system. Parts of gable wall, which fell down on a car in front of the entrance to the Telecom Building, killed a child sitting in the car (Picture-24).

All the columns on the second floor of the Tax Office Building failed in shear and bending. This building had been constructed by a private constructor and later purchased by the state. Low rise buildings (ground and first story) on both sides of this building provided lateral support and column failure occurred in the second floor (Picture-25).

Agricultural Bank Building on the same street, built in early 50’ies had frame and filler wall separation cracks and hinge formation at the ends of some of the reinforced concrete columns (Picture-26).

Details from two collapsed reinforced concrete residential buildings in Ceyhan would be given. Apartment houses of the Hasevler Housing Cooperative built in the Cumhuriyet Mahallesi, southern part of Ceyhan were either severely damaged or totally collapsed. The buildings had been completed three years ago. These five stories high buildings have joisted and filler concrete block filler floor system. Most of them collapsed vertically with total crushing of their ground floors without any considerable lateral movement (Picture-27). This mode of failure implies vertical load carrying structural elements with very low shear force carrying capacity. (Picture-28) shows the upper end of a column with shear failure: there are no closely spaces ties, concrete contains oversized pebbles 7-10 cm, and not surprisingly a large piece of "soil" and the shear crack goes through the soil.

The collapsed building on Picture-29 has interesting features: while the left side of the building collapsed vertically, the right side ground floor with hollow concrete block filler wall did not. The horizontal shear crack in the wall indicates that this wall contributed to the shear force carrying capacity of the ground floor. As seen from (Picture-29), (Picture-30), (Picture-31) the collapsed portion of the building have a large span living room and kitchen with a filler block joist floor system and the floor joists and the shallow beams did not constitute a complete vertical and lateral load carrying frame: This part of the structure did not have a frame system.

(Picture-32) shows reinforced concrete buildings of another housing cooperative in Ceyhan collapsed in a similar fashion as the Hasevler Housing Cooperative apartment houses as mentioned in the previous paragraphs. The load carrying system is similar to the previous buildings. The center and the collapsed part of the building have the large span living rooms of the two adjacent apartments. Here with the joists of almost 8-10 meters span and shallow support beams of joists were unable to form even a vertical load-carrying frame (Picture-33). Vertical collapse of the building with the crushing of the ground floor and without a pronounced lateral displacement of the building again indicates a very low shear and vertical force carrying capacity of the ground floor. If the building had some lateral and vertical load carrying capacity the collapse had been with a amount of considerable lateral displacement with the floors of each story falling on top of each other with large lateral displacement of several meters. Shear failure of a column from another apartment house from the same housing cooperative is given in (Picture-34). The single tie crossing the crack parallel to the short side of the column did not provide sufficient shear force carrying capacity and shear failure was followed by compression failure. Collapse was prevented by the steel frame around the corrugated sheet shop cover and the concrete block filler wall whose top-level blocks were crushed.

Short column failure is observed at ground floor of the Ceyhan Flour Mill where shear walls of upper stories are transformed to columns and the band windows are located (Picture-35).

(Picture-36),(Picture-37),(Picture-38) and (Picture-39),(Picture-40) show shears failures in reinforced concrete columns. Shear failures in reinforced concrete columns are very frequently observed in Turkey due to both very low compressive strength of concrete and due to very sparsely spaced ties and torsion effects resulting from improper conception of structural system and filler walls. (Picture-41) shows cracking of the concrete cover where vertical bars were spliced.

Another feature of the June 27 1998 Adana-Ceyhan Earthquake is the presence of many prefabricated reinforced concrete structures within the maximum intensity region of the earthquake and the level of damage observed in some of these buildings which may spoil the name of reinforced concrete prefabricated structures (Picture-42) Air Compressor Factory Adana Industrial Park). Within the Adana Industrial Park located very close to Misis Town considerable number of factory buildings of prefabricated frame had severe damage and collapse. Another factory with the similar frame system, under construction, near Ceyhan City (Çoþkunlar Ltd. Co.) had all of its roof beams and girders collapsed (Picture-43). This prefabricated reinforced concrete frame system would be described briefly.

Large spans 10-15 meters and more, and high, 4.00 meters and higher, spaces requirements of factories and warehouses are usually met in the last 20-25 years in Turkey by prefabricated reinforced concrete frames. Today a large part of the productions of the companies producing prefabricated elements are used for the construction of large span halls with frame elements of columns, beams and girders and foundation boxes. Columns are placed into box foundations. Beam-column connections of frame elements are connected with various details. The connection details of the prefabricated reinforced concrete frame beam-column are as given in the FIGURE.

External insulation wall of a prefabricated frame building in the Adana Industrial Park separated from the building and the top 2.00 meter portion of external wall and the parapet wall fell down (Picture-44),(Picture-45). The prefabricated frame structure is covered by hollow clay tile wall with a height of 8.0-8.5 meters. There is an insulating layer of styropore material between the wall and the frame. There seems to be no connection between the wall and the frame. The thickness of the wall bricks with lateral perforation is 13.5 cm. While the parapet wall collapsed there was also separation of the external insulation wall at the corners of the building.

There are quite number of water towers in the earthquake region supported by reinforced concrete frames. Many of them had beam column joint damage at the level of the first story. A typical example is shown in (Picture-46), Geçitli water tower. Water towers in Mercimek village built in 1976 and Herekli Village water tower had similar damages. At the beam-column joint vertical bars are not connected by ties and the vertical bars deform outward and break the concrete cover. All the watertoweres in the region require close inspection and repair and strengthening.

Nejat BAYÜLKE , bayulke@deprem.gov.tr Earthquake Research Department -ANKARA

HTML file and picture arrangements made by Nur UMUTLU umutlu@deprem.gov.tr .