Links

SPITAK TRAGEDY SHOULD NOT HAPPEN AGAIN
(On the assessment of the Spitak Earthquake)

Editors: E. Khachyan (Chairman), T. Margaryan, S. Karapetyan, G. Azizyan

Preface
Introduction
Section 1. Main Engineering-and-Seismological Parameters and Social-and-Economic
Consequences of the Earthquake

1.1. Main parameters of the Spitak earthquake occurred on December 7, 1988 (E. Khachyan)
1.2. Geotechnical consequence of the earthquake (R. Haroutyunyan)
1.3. Social-and-economic consequences of the earthquake (A. Alexanyan, S. Kotolikyan, R. Balayan)
1.4. International solidarity and aid for the earthquake zone rehabilitation (A. Alexanyan, S. Kotolikyan, R. Balayan)

Section 2. Engineering Analysis of the Earthquake Consequences, Drawbacks of the Codes and Design Solutions

2.1. Basic constructive solutions for buildings and structures erected in the earthquake zone (G.
Azizyan)
2.2. On main drawbacks in the technology of manufacturing and assembling of concrete and
reinforced concrete structures occurred during construction in the earthquake zone (V. Grigoryan)
2.3. Buildings with masonry bearing walls (T. Margaryan, L. Davidyan)
2.4. Buildings with reinforced concrete bearing structures (R. Badalyan)
2.5. Transport, energy and hydrotechnical constructions (G. Shestopyorov, R. Azoyan, A.
Avetisyan, A. Sargsyan)
2.6. Architectural monuments (S. Shahinyan)

 

Section 3. Basic Concepts of Rehabilitation and Reinforcement of Buildings and Structures Damaged and Being UnderExploitation. On the Main Drawbacks Occurred during Construction in the Earthquake Zone

3.1. The New National Codes for earthquake resistant construction (E. Khachyan)
3.2. Basic concepts of rehabilitation and reinforcement of damaged and exploiting buildings (T.
Margaryan, G. Azizyan)
3.3. On the certification (passport) system for buildings and structures (V. Hambartsumyan, V.
Arzumanyan, H. Aghalaryan, V. Stepanyan, A. Mkhikyan)
3.4. Ways for development of the construction materials and construction industry taking account of the experience of the Spitak earthquake in Armenia (M. Badalyan, P. Ter-Petrosyan, M. M. Badalyan, N. Chilingaryan, A. Asiryan)
3.5. New experience in application of contemporary seismic protection systems in reinforcement of new constructions and buildings under exploitation (M. Melkumyan)
3.6. The new system of normative-and-regulating documents of the Republic of Armenia in the
field of construction (T. Margaryan, S. Karapetyan)
3.7. The state system for urban development activity regulation (S. Tovmasyan, A. Manukyan,
A. Margaryan, V. Novikov)

Appendix A. Extracts from the “Opinion about quality of design and construction of residential public buildings in the northern regions of the Armenian SSR, causes of their destruction and improvements in design and construction in regions with high seismic activity” of the State Commission.

Appendix B. The list of the normative-and-regulating documents published in the connection with the December 7, 1988 earthquake consequences’ elimination and improvement of seismic resistant construction.

SUMMARY

Section 1
On December 7, 1988 in the northern regions of the Republic of Armenia a destructive earthquake, which later on was called the Spitak earthquake, had occurred. As a result of this earthquake thousands of constructions were damaged and collapsed, which led to tens of thousand people’s martyrdom.

The earthquake had stricken at 11:41:24 AM local time, on December 7, 1988. The geographical coordinates of the earthquake epicenter are 40.99° E and 44.2° N. The depth of the earthquake center was 11 km, its magnitude according to surface waves was Ms=6.8, and according to vertical components it was Ms=7.0. Energy released during the earthquake was 11×1014 J. As the result of the earthquake 38-km-long cracks appeared on the earth surface. The movement was of a right strike-slip character. The vertical displacement of the earth surface had reached up to 2 m, and the horizontal one – up to 0.55 m (Fig. 1.5, 1.6, and 1.6a). The earthquake had many aftershocks, the most powerful of them occurred 4 min 20 sec after the main shock and had the magnitude of Ms=6.2. The records of ground accelerations during the earthquake taken in Ghukasyan (0.20g), in Yerevan (0.06g) and in the site of the Armenian Nuclear Power Plant (0.03g) are shown in Figs. 1.8, 1.9 and 1.10. The earthquake intensity, according to estimate of experts and the data of CBM seismographs located in Gyumri, Yerevan and Stepanavan reached the level of X in Spitak, IX in Gyumri, VII-IX in Stepanavan, VI in Yerevan, and V in Ararat, according to MSK-64 scale. The earthquake caused big changes and displacements on the earth surface (Figs. 1.2.2, 1.23 and 1.2.4). The largest displacement (about 2 m) appeared in the vicinity of Geghasar at the altitude of 1950 m. The circular gap with a diameter of 3 to 4 m appeared in the vicinity of the Geghasar village. Significant soil dilution appeared near the Nalband village, which caused heavy damages to a 230-m-long section of the railway (Fig. 1.2.8). The highway was also damaged by 40 to 50-cm-wide cracks (Fig. 1.2.9).

The earthquake had damaged mostly Spitak (100%), Gyumri (75%) and Vanadzor (25%). The level of damages in villages was about 34 %. Large destructions in Gyumri were partially caused by unfavourable ground conditions, especially in the case of 9-storey buildings of the 111 series.

About 40% of the republic’s territory with the population of about 1 million, was damage by the earthquake. 25,000 people had fallen a pray to the earthquake, 19,000 had been injured, and more than 500,000 had been left homeless. Twenty one towns and regional centers were collapsed either partially or totally, 20 5 of residential buildings, hundreds of schools and children care institutions, more than 2,000 objects of public health, culture, trade and public utilities were either destroyed or heavily damaged. The earthquake damaged more than 9 million sq. m of dwelling area, 4.7 sq. m of which were totally collapsed or subject to demolition because of heavy damages. 230 industrial, 80 processing and 300 collective farm objects and 244 cattle-breading farms were destroyed either totally or partially. The total damage caused by the earthquake was more than 13 billion roubles. The earthquake had influenced the people’s psychology negatively. It revealed serious drawbacks in the field of seismic protection in the Republic.

The Spitak earthquake had risen a broad response all around the world. Thousands of persons, physicians, rescuers, art and culture workers, deputies of parliaments, ministers, leaders of countries and governments from every corner of the world offered a hand of help to the Armenian people. As the aid Armenia had received a large amount of transfusion blood, foodstuff, clothes, medical equipment and medicines, etc. Mr. N. E. Rizhkov, the USSR Prime Minister, headed the whole organizing work on the aid. Immediately after the earthquake the representatives of Georgia offered their help to Armenia. Citizens of France, Greece, the UK, Canada, Austria, Italy, Algeria, Yugoslavia, Poland and the USA participated actively in the rescue operations. Thanks to their self-sacrificing work lives of thousand people were saved. Inestimably large volume of work was carried out by thousands of pilots from various countries. The scale of medical aid were incomparable. 417 doctors from 17 countries arrived to the earthquake zone. 10,000 people were hospitalized during the first 3 days and 6,000 doctors helped them. Works carried out by I. I. Chazov, P. I. Chernyaev, K. I. Kozubey, I. V. Tophan, O. Godushauri (USSR), N. Khancze (Vietnam), Miki Vineri (Israel), and many others in medical help to the earthquake victims were inestimable. 40,000 people from the earthquake zone were evacuated to Georgia, the Crimea, Stavropol and Kuban Territories. Thousands of children and injured persons received medical help in hospitals of the USA, Italy, France and Germany. Dozens of first necessity objects and industrial enterprises were rehabilitated during the first days after the earthquake with the help of specialists from various countries. The program of great rehabilitation works began to be implemented since the beginning of 1989. It was foreseen to put into operation 5.3 million sq. m of dwelling area, to construct many schools and hospitals during 2 years. All the Union Republics were involved into this work (Table 1.4.1). The total sum of donations from private persons from the former USSR, which were directed to the earthquake zone rehabilitation, amounted about 1.4 billion roubles. The sum of material aid from foreign countries amounted 500 million USD, that of the financial aid – 8-million USD, and the aid from the Armenian Diaspora was 50 million USD. The USA Congress additionally allocated 10 million USD to Armenia. The UK, France, the USA, Italy, Germany, Austria, Switzerland, Czech Republic and other more than 20 countries (Table 1.4.2) carried out works of large volume on construction and rehabilitation. These works included construction of 346,000 sq. m of dwelling area, schools for 4,722 places, children care institutions for 1,480 places, hospitals for 2,015 places, 71 polyclinics, etc. The following persons were outstanding due to their activity and private means donation to help the Armenian people such as G. Bush, R. Reagan, G. Baker, R. Dole, G. Dokmegian, A. Hammer, D. Peterson (USA), I. Rau, L. Shpat (GDR), P. Zakarian (Denmark), D. Galerman (Israel), Mother Theresa (India), A. Khashemi (Iran) and many others: artists, musicians, doctors, scientists, clergy, public figures, parliamentarians, and pupils. The Armenian people expresses its gratitude to all the countries, organizations and persons who provided their material, financial and moral assistance in that hard days of the earthquake and the following years.

Section 2.
The book presents construction solutions for dwelling and civil buildings constructed in the urban and rural areas of the (earthquake) disaster zone, as well as specific features and drawbacks of these solutions based on the Seismic Resistant Construction Codes requirements. Based on constructive solutions and applications, buildings are presented in the following basic groups: masonry and large-block buildings, frame panel buildings and large-panel buildings. At the same time, the constructive solutions widely used in the other regions of the Republic are analyzed as a separate group.

There are mentioned the typical technological drawbacks and violations, which were committed in construction and in manufacturing of prefabricated reinforced concrete structures. They are related to the constructions’ reinforcement and anti-seismic measure implementation. These drawbacks are analyzed based on the studies of quality of construction-and assembling work in the disaster zone, as well as in the other regions of the Republic. Those drawbacks and violations, that were committed in transportation of prefabricated reinforced concrete elements and structures and also during storage and assembling on construction sites, were analyzed as well. Of course, they impacted significantly seismic stability of buildings.

The behaviour of buildings and constructions with various constructive schemes during the earthquake is analyzed in this section.

Buildings with masonry bearing walls. One or two storeyed and multi-storeyed (3 to 5 storeyed) buildings with masonry bearing walls constituted a basis of urban and rural dwelling buildings in the disaster zone. From the viewpoint of building behaviour during the earthquake, the following classification can be made: disastrous – in Spitak and surrounding villages; destructive – in Leninakan (Gyumri); and heavy – in Kirovakan (Vanadzor) and Stepanavan. Damage extent, character and spreading were diversified depending on a number of factors such as constructive solutions of buildings, number of storeys, hydrogeological and geotectonic conditions, anti-seismic measures’ specific features and their efficiency, quality of construction-and-assembling works, etc. Particularly, the data presented here indicates that in case of other equal conditions the damage extent for masonry buildings essentially depends on accepted spatial-and-plan and constructive solutions. It is highlighted by the behaviour of dwelling buildings erected at various times. Besides the above mentioned and other factors, the following specific characteristics of the earthquake have played a destructive role in behaviour of buildings: high intensity of the earthquake compared to the normative ones; rather long duration; strong shocks’ repetitions; presence of vertical components, etc. The analysis of the
behaviour multi-storeyed buildings with masonry bearing walls during the earthquake demonstrated once again non-rational constructive-and-plan solutions for some typical buildings (Fig. 2.1). The main design drawbacks of typical buildings are the following:

- Application of large concrete blocks together with masonry in the walls within one storey (almost for the height of a storey);
– Difference in the schemes of building’s middle and frontal sections’ constructive solutions, as well as absence of frontal bearing walls in the frontal sections, in case of deep balcony in this parts;
– Absence of internal longitudinal walls in the middle sections, in case of presence of large openings in external walls; reinforced concrete frame constructive solution for the first storey (a shop storey), which was most likely led to drastic reduction of building’s stiffness after the first strong shocks. It was transformed into a scheme with first “flexible storey”. Having inadequate resistance, the above scheme was destroyed and in some cases collapsed after the next horizontal seismic shock. About 90% of the dwelling constructions in Gyumri were l-to-2 storeyed dwelling buildings (their number was approximately 11,000 ones). A considerable part of these buildings were erected long ago and withstood the 1926 earthquake (its intensity in Gyumri was estimated as being 8). Some of these buildings were repaired after the 1926 earthquake, and some constructive measures for reinforcement were carried out, such as steel belts on the roof level. These buildings endured the Spitak earthquake impact quite satisfactorily (Fig. 2.18).

The quality of construction-and-assembling works in the buildings with masonry bearing walls was unsatisfactory. In many cases the brickwork did not meet the constructive-and-technological requirements (particularly, in the case of combined constructions) because of which the essentially monolithic character and bearing capacity were not preserved at due level (Fig. 5.10). Due to a low quality of works the actual resistive capacity of buildings to seismic forces was significantly lower than the designed ones.

Buildings with reinforced concrete bearing structures. Residential, public and industrial buildings with reinforced concrete bearing structures in mostly damaged towns had behaved differently during the earthquake. In Spitak (which was located closer to the epicentral zone) they were destroyed everywhere. Distortion of buildings in the town of Gyumri was also disastrous. Approximately 80% of buildings was either heavily damaged or collapsed. The number of damaged buildings in Vanadzor was significantly lesser (approximately 50% was damaged).

95 from 138 of 9-storeyed (including 12-storeyed) frame panel buildings of the 111 series were totally collapsed in Gyumry, and the remaining ones were in such condition that it was more expedient to demolish them. Only 5-storeyed buildings of the same series, which were designed for 9-intensity earthquake, remained standing, while in Vanadzor ninety six 9-storeyed buildings of the same series remained standing and some of them were damaged (these damages should be repaired). Overwhelming destruction of 9-storeyed panel frame buildings of the 111 series may be explained by a combination of the following unfavourable factors: considerable exceeding of the actual intensity over the designed one; spectral features of the earthquake forces; presence of excessive vertical forces; features of constructive-plan solutions of frame buildings; and, of course, low quality of construction-and-assembling works.

The presented analysis of constructive-and-plan solutions indicated that there were some vulnerable places. In particular, joints of column junctions to each other were vulnerable to shear forces appearing because of the earthquake shocks; despite they were organized in so called “zero” sections (Fig. 2.3.10). Both one-sectional and multi-sectional diaphragms were located non-symmetrically. The diaphragms’ panels were jointed to columns at 3 levels on the one side, and only at one level on the other side, which, of course, was insufficient. From the viewpoint of bar anchoring these solutions for diaphragm’s and linking panels’ joining were improper and the low quality of construction contributed greatly to their vulnerability. Joints of frame column junctions with girders (Fig. 2.3.14) were vulnerable due to both their constructive solutions and their location (they were located in maximum strain points, which contradicted to the Construction Codes requirements). Joints of hinged panels of outer walls and frame girders junctions (Fig. 2.3.15) were solved so that during seismic shocks the panels and the frame actually worked together increasing the stiffness.

Conditions of large-panel buildings erected in the disaster zone were of the other pattern. Sixteen 9-storeyed large-panel buildings constructed in Gyumri withstood the earthquake impact quite satisfactorily (Fig. 2.3.1). Based on large-panel building’s behaviour during the earthquake it may be assumed that the construction system of large-panel buildings user in the Republic, despite some drawbacks in designing and construction, displayed itself as a quite reliable and earthquake-resistant one.
The analysis of 10-and 16-storeyed buildings erected by the storey elevating method in Gyumri, as well as industrial frame one-storeyed and multi-storeyed buildings, which were constructed using the ИИC-04 series frame, due to rigid junctions of girders and columns, were more stable seismically compared to one-storeyed industrial frame buildings.

Transport, energy and hydrotechnical structures. The behaivour of the railway subgrade, bridges, railway tunnels, transport power supply, communication and other buildings, as well as roads, including bridge structures located in the epicentral zone during the earthquake, were analyzed. Damages caused by the earthquake to energy structures located in the earthquake zone, particularly, to the buildings of the Kirovakan (Vanadzor) electric power plant were analyzed as well. There are also indicated damages caused to buildings of hydroelectric power plants, which were subject to 8-intensity earthquake.

In the disaster zone the objects of the northern and western electric networks were heavily damaged, and buildings of the Spitak district network were practically collapsed completely. The network objects of Gyumri and Vanadzor were damaged partially.

Architectural monuments. During the Spitak earthquake 73 architectural monuments from 151 ones located in the northern region of Armenia were damaged or destroyed (completely or partially). The Amenaprkich Church in Gyumri was one of them. 347 buildings were heavily damages, including the S. Astvatsatsin and S. Nshan churches in Gyumri. Practically all other architectural monuments were damaged partially.
The details concerning the behaviour of large monumental buildings in Gyumri (Leninakan) such as the Amenaprkich, S. Astvatsatsin and S. Nshan churches, architectural monuments on Aragats St., as well as the behaviour of tombstones in the cemetery are presented, and they point out that considerable damages were observed in the Leninakan cemetery, compares to the other towns.

Section 3
The above mentioned consequences caused by the earthquake indicate that there were serious drawbacks in the field of construction before the earthquake in Armenia, both in estimation of seismic hazard level in the territory of the Republic and in the field of designing and construction of buildings and structures.

The elaboration of the new National Codes for earthquake resistant construction was the most significant contribution in providing seismic safety after the earthquake. The new RACN II-2.02-94 Codes were worked out in 1991 – 1994; they substituted the former USSR SNIP II-7-81* and were entered into force since 1995. It is known that after the Spitak earthquake the whole territory of Armenia was defined as the 9-intensity earthquake region may be shifting from one extremity to another. The new Codes also include a new map of seismic zonation, according to which the territory of Armenia is divided into three zones, which are not so much differing from each other in the terms of intensity level. These zones, designated as Zones 1, 2 and 3, constitute 15, 50 and 35% of the whole territory of Armenia, respectively. The values of ground acceleration in these zones are accepted as 0.2g, 0.3g and 0.4g, correspondingly. According to the new Codes, soil is classified into four types with new K0 coefficient values being 0.8, 1.0, 1.0 and 1.4. Based on the geographical data of construction sites the new Codes provide designers with an opportunity to avoid the possibility of resonance conditions in buildings during earthquakes. The Codes contain a number of new provisions for definition of seismic forces. Particularly, there are considerable changes in dynamic coefficient ? (T), which in the contrast to the old one, lead to reduction of seismic forces during an earthquake in case of rigid structures and vice versa, their increase in case of flexible structures. The value of K1 coefficient characterizing a permissible level of damages is also changed considerably. It depends on building’s constructive solutions and construction materials used in bearing structures, due to which reliability of buildings is significantly increased in case of an earthquake. The Codes specify additional measures for increasing reliability of special purpose constructions when designing them. The Codes also specify methods for calculation of ground motion’s vertical component, rotational motions and “base-structure” interaction during earthquake. They contain the recommendations for estimation of damages to buildings, building rehabilitation or reinforcements. The reasons and substantiation of all these changes are given in the present book.

The basic provisions for rehabilitation reinforcement measures’ implementation in the earthquake zone after the earthquake, information on their volume and terms of implementation are given. The “Haypetnakhagits” (Armenian State Design) Institute worked out 34 standard designs for reinforcement of mass-scale series buildings, but these designs have not been implemented because of the social-and-economic and political changes occurred. During 1989 to 1993 only 14 building have been reinforced. In 1993 a new program for rehabilitation and reinforcement, which was more realistic than the previous one, was worked out. For building with the 1st and 2nd degrees of damages it was intended to rehabilitate them to the conditions they had before the earthquake. The provisions for reinforcement and rehabilitation of buildings with the 3rd and 4th degrees of damages were specified too. Advantages of the contemporary methods of rehabilitation and reinforcement and the fields of their applications were indicated as well.

In the connection to increasing of seismic hazard level in the territory of Armenia and acceptance of the new Codes concerning seismic resistant construction, the present level of seismic resistance of buildings and constructions under exploitation in the whole territory of Armenia is unsatisfactory. To this end the task of special studies, introduction of a certification (passport) system for specifying building’s technical conditions and the order and extent of further reinforcement is specified. Basic provisions for introduction of a certification system for buildings and constructions of various purposes, standard samples of certificates (passports) of certified buildings and constructions are also given.

The main problems of study and classification of construction material properties and construction elements manufacturing play an important role in providing seismic resistance of buildings. Reduction of construction elements’ weights is conditioned by improvements in manufacturing technologies and comprehensive investigations of construction material properties. The paper describes those modern technological innovations, which allow using local rocks, and, applying some additional materials, to obtain lighter construction and constructive-and-thermoinsulating materials and structures and buildings based on them. Particularly, a great part of this paper is devoted to the investigations of so called cement-free binding materials and physical-and-chemical processes in concrete based on them, as well as of strength and therotechnical properties of these concretes.

Recently, Armenia carried out positive experiments in providing seismic resistance for new constructed buildings and in increasing the level of seismic resistance for buildings under exploitation in the sphere of application of the modern methods for seismic protection (dynamic dampers, steel-and-rubber stratified “pads”, etc). Particularly, in Spitak there are two objects designed with application of steel-and-rubber pads – 4-storeyed monolith reinforced concrete apartment building. The seismic resistance of 9-storeyed buildings of the 111 series, which withstood the earthquake, is increased by application of so called “upper flexible storey” construction method (Fig. 3.5), while in two building the upper flexible storey method is implemented using steel-and-rubber pads (upper separated storey). For the first time 5-storeyed IA-450 series apartment building with masonry bearing walls, which is under exploitation, was isolated from the basement by means of steel-and-rubber pads. On the opinion of specialists the experience of these works will gain wider application in the future.

The analysis of the 1988 Spitak earthquake’s heavy consequences has shown that the basic provisions of normative-and -regulating documents in the field of construction shall be revised completely. During a short period of time passed after the earthquake a number of normative and regulating documents were worked out and applied (Appendix 2) in construction and rehabilitation of the earthquake zone. “The basic provisions of normative-and-technical documents system in the field of construction” and the first normative document of the Construction Codes System RACN 1-1.01-95 entitled “System of Norms and Standards in Construction. Basic Provisions”, where the contemporary legal and social-and-economic specific features of the Republic were taken into account, have been worked out and approved. A number of construction norms, national standards and other normative documents, which regulate seismic-resistant construction in the Republic, have been developed and approved.

Armenia actively participates in the work of the CIS intergovernmental scientific-and-technical committee, which is engaged in development of normative documents in the field of construction.

The National Assembly of the Republic of Armenia adopted the Law of the Republic of Armenia “On Urban Development”, and based on this law the state and regional authorities and local self-governing bodied established, by their corresponding activities and resolutions, the State System of Urban Development Activity Regulations, which covered expertise of designing, supervision f construction quality, licensing and legal aspects of construction production’s registration.

The development of a new system of normative-and-technical and regulating documents in the field of construction, studies aimed at improvement of construction materials manufacturing and construction technologies, creation of legal framework, expertise in designs, supervision of construction quality, and improvement of licensing procedures, works carried out currently to increase level of seismic resistance of buildings and structures under exploitation, create an opportunity to provide favourable conditions for urban development activity and give a hope to exclude the repetition of the Spitak disaster in the future.

Leave a Reply