A probabilistically based hazard map of Albania expressed in terms of PGA for 475 years of return period following the spatially smoothed seismicity approach proposed by Frankel (1995) and developed by Slovenian researchers (Lapajne et al. 1997), is presented. Taking advantage of this development, an effort has been made to analyze the parameters of site-dependent acceleration response spectra parameters of the current seismic design code KTP-N.2-89 in Albania.
Authors:D. Lungu, A. Aldea, S. Demetriu, and I. Craifaleanu
According to the number of people lost in earthquakes during 20th century as well as in a single (March 4, 1977) earthquake during this century (1574 people, including 1424 in Bucharest), Romania can be ranked the 3rd country in Europe, after Italy and Turkey. Romania is followed by the former Yugoslavia and by the Greece (Bolt 1995, Coburn and Spence 1992). The World Bank loss estimation after the 1977 earthquake (Report No. P-2240-RO, 1978) indicates that from the total loss (2.05 Billion US) more than 2/3 was in Bucharest, where 32 tall buildings collapsed. Half of the total loss was accumulated from buildings damage. The 1977 direct loss and indirect consequences of loss mark probably the starting point of economical decay of Romania during the next decade. They also explain the present concern of civil engineers and Romanian Government for assessment and reduction of seismic risk in Romania. The World Map of Natural Hazards prepared by the Münich Re (1998) indicates for Bucharest: "Large city with Mexico-city effect". The map focuses the dangerous phenomenon of long (1.6 s) predominant period of soil vibration in Bucharest during strong Carpathians Vrancea earthquakes. The Bucharest and Lisbon are the only two European cities falling into Mexico-city category. International experts and organizations agreed that Bucharest is the capital city in Europe characterised by the highest seismic risk. The paper presents: 1. Codes and standards for design of earthquake resistance of structures (1940-2000) and the draft of the new seismic Romanian code P100; 2. The structure of existing building stock in Bucharest; 3. The most vulnerable to earthquake categories of buildings, located on the soft soil condition of Bucharest: -tall reinforced concrete buildings in central Bucharest built prior to 1940 and severely damaged by the past 1977 event;tall reinforced concrete buildings with soft ground-floor built in Bucharest prior to 1977. Hospitals buildings, university buildings and other buildings, classified as having a high risk of severe damage/collapse in case of a strong earthquake; Enlargement of the existing seismic networks of Romania by two recent projects of INCERC and State Inspectorate for Construction and of NCERR and Japan International Cooperation Agency. In the last 6 months in Romania, the two projects provided about 50 (18 in Bucharest) digital Kinemetrics instruments (K2 and ETNA): in free field condition, in deep boreholes as well as in tall buildings.
according to a pre-1970 designcode (ACI 1968) [ 2 ]. The buildings are of heights five, ten, and fifteen stories that represent low- and medium-rise buildings. The three buildings have the same floor plan that consists of five symmetrical bays in each
We applied deterministic and probabilistic methodologies for seismic hazard assessment at Tirana city, expressed in terms of horizontal peak ground acceleration (PGA). The deterministic evalues of PGA are determined according to the scenario
= 6.4 km and
= 6.0, while the probabilistic ones have been assessed applying the smoothed seismicity approach. The results that derive from the two methodologies show equal values of PGA for the selected site inside Tirana city and higher than the PGA values established by the official maps as well as the actual seismic coefficients that are being applied by the actually in force national design code KTP-N.2–89 for Tirana area.
Authors:Adriana Ioan, Aurel Stratan, and Dan Dubina
Eccentrically braced frames are widely used as lateral-force resisting system for multi-storey buildings located in seismic areas. Capacity design principles used in modern seismic design codes are deemed to constrain plastic deformations to dissipative elements only, which in eccentrically braced frames are represented by links. The aim of using these frames is to reduce the repair costs and downtime of a structure hit by an earthquake. This objective is to be attained through removable dissipative members (bolted links) and re-centering capability of the structure. Numerical studies are performed in order to investigate the practical feasibility of the replacement procedure; analyzing dual frames obtained by combining steel eccentrically braced frames with removable bolted links with moment resisting frames. Practical solutions regarding order in which bolted links need to be replaced are proposed, as well as the mounting of some temporary tie braces, for safety measures during the link removal procedure.
Authors:Andrei Crişan, Viorel Ungureanu, and Dan Dubina
The paper summarizes the results of experimental and numerical investigations, carried out at the CEMSIG Research Center (
) of ‘Politehnica’ University of Timisoara, on compression members of pallet racks. Members of two different cross-sections, with and without perforations, have been tested on the aim to calibrate a design approach to evaluate their ultimate strength and, on this basis, to check the buckling resistance of bar members accounting for distortional-global interaction. The lengths of upright specimens and testing procedure, for local and distortional buckling, were chosen according to European pallet rack design code provisions. Test on base materials and imperfection measurements have been also performed. In order to study the distortional-global interactive buckling, the ECBL method has been used. The paper presents the main results of these investigations.
Authors:A. Fundo, Duni Ll, Sh Kuka, E. Begu, and N. Kuka
A new probabilistic seismic hazard assessment for Albania is carried out using the smoothed gridded seismicity approach. Albania’s earthquake catalogue is already revised and expanded, covering a study area limited by 38 − 44.5°N Latitude and 18 − 24°E Longitude, and the time period from 58BC to 31/12/2008. The ground motion hazard map is presented over a 10 km grid in terms of peak ground acceleration for 10% probability of exceedance in 50 years, corresponding to 475-year return period. The reference site condition is firm rock, defined as having an average shear-wave velocity in the upper 30 m of the crust of 800 m/sec. It is the standard reference site condition used by the European seismic code (Eurocode 8) for seismic zonation and building codes. The main finding is that if this map is accepted as a reference indicator to establish a new regulatory national seismic zonation, design acceleration will be much higher than that applied in the current regulation. This implies that the competent authorities should take into consideration the obtained results to improve the existing design code in a more reliable and realistic basis in order to increase the safety level of constructions in the country.
Authors:Cristian Vulcu, Aurel Stratan, and Dan Dubina
Dual-steel structural systems, in which mild carbon steel is used in dissipative members while high strength steel is used in non-dissipative ‘elastic’ members, can be very reliable and cost efficient. Because present seismic design codes do not cover this specific configuration, a research project started with the aim to investigate and evaluate the seismic performance of dual-steel building frames. The frames are considered to be moment resisting frames, dual concentrically braced frames and dual eccentrically braced frames. The paper makes a short description of the research project and the experimental program to be performed at the ‘Politehnica’ University of Timisoara.A number of numerical simulations have been performed for the beam-to-column joints that will be tested with the aim to assess their behavior under monotonic as well as cyclic loading. The material model used in the numerical simulations was calibrated based on the results from tensile tests. The assumptions considered in the modeling of the specimens, the loading procedure, as well as the results from the numerical analysis are finally presented.
Authors:Norin Filip-Vacarescu, Aurel Stratan, and Dan Dubina
1998-1 2004 , Design provisions for earthquake resistance of structures: General rules — Seismic actions and general requirements for structures, CEN, EN1998-1-1.
P100-1/2006, Seismic designcode, Part I (in Roman)