Seismic and Structural Analyses of the Eastern Anatolian Region (Turkey) Using Different Probabilities of Exceedance

Seismic hazard analysis of the earthquake-prone Eastern Anatolian Region (Turkey) has become more important due to its growing strategic importance as a global energy corridor. Most of the cities in that region have experienced the loss of life and property due to significant earthquakes. Thus, in this study, we attempted to estimate the seismic hazard in that region. Seismic moment variations were obtained using different types of earthquake magnitudes such as Mw, Ms, and Mb. The earthquake parameters were also determined for all provincial centers using the earthquake ground motion levels with some probabilities of exceedance. The spectral acceleration coefficients were compared based on the current and previous seismic design codes of the country. Additionally, structural analyses were performed using different earthquake ground motion levels for the Bingöl province, which has the highest peak ground acceleration values for a sample reinforced concrete building. The highest seismic moment variations were found between the Van and Hakkari provinces. The findings also showed that the peak ground acceleration values varied between 0.2–0.7 g for earthquakes, with a repetition period of 475 years. A comparison of the probabilistic seismic hazard curves of the Bingöl province with the well-known attenuation relationships showed that the current seismic design code indicates a higher earthquake risk than most of the others.

A comparative study on the structural performance of an RC building based on updated seismic design codes: case of Turkey

The destructive earthquakes and structural damages reveal the importance of the rules of earthquake-resistant structural design. The need of update and renewal of these rules periodically become inevitable as a result of scientific developments, innovations in construction technologies and building materials. Turkey which is an extremely region in terms of seismicity was adapted to these changes through time. The last five seismic design codes (1968, 1975, 1998, 2007 and 2018) were taken into account within the scope of this study. The differences in dimension and material grades of structural elements such as columns as beams have been compared in detail for each code. Three different analysis types have been performed for a 4-story reinforced-concrete model such as eigenvalue, pushover and dynamic time-history via the minimum conditions for these elements in each code. The natural vibration period of the building was obtained with empirical formulas stipulated in different codes for the sample RC building, additionally. The size and the type of the materials used in beams and columns within the last five codes have been changed. We see that the changes in these two important parameters which affect the behavior of buildings during an earthquake, enhance the performance of the building. It has been revealed that changes and renewals in seismic design codes are a necessity and gain. It has been clearly revealed that each amended code increases the stiffness and enhance the seismic capacity of a structure. Each updated seismic design code is aimed to complete the deficiency of the previous one. The results revealed that there are changes to be made to increase the seismic capacity of the structure at the point of reducing earthquake damage.

Research on determining the aseismic performance level of reinforced concrete building

In seismic design based on performance, seismic performance level is determined based on failure state of the building and seismic design objective is set according to the importance of the buildings. In many countries, they calculate the seismic reaction of the buildings with the use of structural design programs to check the aseismic performance through the nonlinear static analysis method. In this paper, we established seismic performance levels and aseismic design objective to design on the basis of design objective according to the three levels in Seismic Design Code of Building, DPR Korea, 2010.

Rapid power outage estimation for typical electric power systems in Turkey

Electric power systems have critical importance in the sustainability of social life and economy. The past and recent earthquakes showed clearly that these systems have high vulnerability due to earthquakes. In this study, the typical electric power systems which are commonly preferred and located at five different sites in high seismic zone of Turkey, Marmara region, have been examined. In the first part of the study, the earthquake hazard for Marmara region has been accomplished. The earthquake hazard curves at five different sites for two different earthquake levels, and two different site conditions as soft and stiff site classes according to the Turkish Building Seismic Design Code 2018 have been obtained. The seismic vulnerability assessment of substation and distribution circuits for two different design states, namely anchored and unanchored, achieved by the fragility functions. The probability of power outage durations have been evaluated based on the restoration curves. It has been observed that the results obtained within the scope of the study are highly consistent with post-earthquake studies in the literature. The proposed methodology through the power outage graphics enable a quick preliminary evaluation of the power outage based on the current design status and location for any electric power systems in the Marmara region.

Torsion-based layout optimization of shear walls using multi-objective water cycle algorithm

In shear wall-based buildings, locating the shear wall in plan has an important role in the resistance of seismic loading. In this article, the minimum torsion is considered as one of the main goals for optimal layout of shear walls, unlike the common method that accepts a certain torsion limit. The method presented is in accordance with the principles of design codes with emphasis on reaching the least possible torsion effect. By using a multi-objective function, based on the Pareto solutions, the torsion function behaves against the cost of a structure subjected to constraints of flexural strength, shear strength, and drift. This approach has the ability to layout shear walls in irregular plans and those which have high architectural limits. Also, it can fulfill the main goal of a structural engineer in order to satisfy the requirements of an architectural plan and obtain its minimum torsion effect as well. This method has been applied to various types of regular and irregular plans according to the classification of seismic design codes. Results show that besides minimizing the cost, the torsion effect reaches the minimum possible value considered by the seismic design code, as compared with other methods.

Seismic Design Optimization Method of Fire Hydrants

As per the revisions to the Korean Building Code and the Seismic Design Code for fire protection systems in accordance with the Common Applications of the Seismic Design Code by the Ministry of the Interior and Safety, earthquake load and structural safety of a non-structural element are considered as important parameters for a fire protection system. In Richter scale 5.0 or higher earthquake damage cases occurring in Gyeongju (2016) and Pohang (2017), walls and hydrant boxes were broken or deformed such that their doors could not be opened. Therefore, the breakage, deformation, and detachment of hydrants and internal devices without the seismic design caused malfunction and increased the fire risk. In this study, the earthquake load was calculated according to the seismic design regulation on the hydrant box and the structural stability was verified by 3D model review, structural analysis simulation, the structural member, and the anchorage for performance. Moreover, an optimized seismic design plan was proposed by analyzing and comparing the simulation result for the factors governing the seismic design performance of a fire hydrant box.

Experimental Study on the Behavior of Existing Reinforced Concrete Multi-Column Piers under Earthquake Loading

When a seismic force acts on bridges, the pier can be damaged by the horizontal inertia force of the superstructure. To prevent this failure, criteria for seismic reinforcement details have been developed in many design codes. However, in moderate seismicity regions, many existing bridges were constructed without considering seismic detail because the detailed seismic design code was only applied recently. These existing structures should be retrofitted by evaluating their seismic performance. Even if the seismic design criteria are not applied, it cannot be concluded that the structure does not have adequate seismic performance. In particular, the performance of a lap-spliced reinforcement bar at a construction joint applied by past practices cannot be easily evaluated analytically. Therefore, experimental tests on the bridge piers considering a non-seismic detail of existing structures need to be performed to evaluate the seismic performance. For this reason, six small scale specimens according to existing bridge piers were constructed and seismic performances were evaluated experimentally. The three types of reinforcement detail were adjusted, including a lap-splice for construction joints. Quasi-static loading tests were performed for three types of scale model with two-column piers in both the longitudinal and transverse directions. From the test results, the effect on the failure mechanism of the lap-splice and transverse reinforcement ratio were investigated. The difference in failure characteristics according to the loading direction was investigated by the location of plastic hinges. Finally, the seismic capacity related to the displacement ductility factor and the absorbed energy by hysteresis behavior for each test were obtained and discussed.

Observations from the 26th November 2019 Albania earthquake: the earthquake engineering field investigation team (EEFIT) mission

On the 26th of November 2019, an earthquake of moment magnitude 6.4 struck the northwest region of Albania as the result of thrust faulting near the convergent boundary of the Africa and Eurasia plates causing widespread damage to buildings in the city of Durrës and the surrounding areas. Based on the official data from the national authorities, the earthquake caused 51 casualties and 985 million-euro losses, corresponding to 7.5% of the 2018 gross domestic product. This paper summarises field observations made by the Earthquake Engineering Field Investigation Team (EEFIT) after the event. The paper presents an overview of the seismological aspects of the earthquake together with a brief overview of the damage, official loss statistics and the estimated macro- and socio-economic consequences of the event. In addition, it provides a summary of the observed damage to both recent and historical buildings as well as the description of several case studies to illustrate the characteristic damage patterns observed in the main structural typologies of the Albanian building stock. These observations try to identify possible links between the observed damage patterns and the deficiencies in construction practice and use of inappropriate retrofit techniques for historical assets. As many severe damages were observed on modern buildings, this also allows the identification of some gaps and possible areas of development of the current seismic design code. In the end, the lessons learned from the field survey are resumed.

Analytical Evaluation of MCE Collapse Performance of Seismically Base Isolated Buildings Located at Low-to-Moderate Seismicity Regions

The promising seismic response emerged by the concept of base isolation leads to increasing practical applications into buildings located at low-to-moderate seismicity regions. However, it is questionable that their collapse capacities can be ensured with reasonable reliability, although they would be designed according to a current seismic design code. This paper aims to investigate the collapse capacities of isolated buildings governed by the prescribed design criteria on the displacement and strength capacities of the employed isolation systems. In order to evaluate their collapse capacity under maximum considered earthquakes (MCEs), simplified numerical models are constructed for a larger number of nonlinear incremental dynamic analyses. The influential factors on the collapse probabilities of the prototype buildings are found out to specifically suggest the potential modifications of the design requirements. Although the MCE collapse probabilities of all isolated buildings are smaller than those expected for typical non-isolated buildings, these values are significantly different according to the degree of seismicity. The MCE collapse probabilities are dependent upon the governing collapse mechanism and the total system uncertainty. For the prototype buildings located at low-to-moderate seismicity regions, this study proposed the acceptable uncertainty to achieve a similar collapse performance to the corresponding buildings built at high seismicity regions.