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Samos Earthquake caused the collapse of about fifty buildings in Izmir city center, resulting in over 120 fatalities. The response spectra of the ground motions at the soft soil sites in Izmir revealed that the spectral accelerations in the period range of 0.5-1.5 s are similar to the spectral accelerations defined by the response spectrum corresponding to the 72-year return period. Despite experiencing accelerations lower than those defined by the Turkish Code design spectrum (475-year return period), significant damage was observed due to the deficiencies of the building stock. Several factors such as soft story, lack of code-compliant transverse steel reinforcement, and low concrete strength have contributed to the devastating loss. Studies in the last two decades on deformation capacity estimation of RC columns showed that key parameters for collapse drift limits are the axial load ratio (i.e., axial force demand to capacity ratio) and transverse reinforcement amount. Most of the collapsed buildings in the past Turkish earthquakes had low concrete strength resulting in high column axial load ratios with limited drift capacity. In order to identify the collapse of vulnerable buildings, a simple procedure is proposed based on vertical and lateral pushover analysis results. The method relies on estimating the average axial load ratios of the most critical columns and their seismic drift demands. An axial load ratio-drift demand limit state model was developed to identify the buildings with high collapse risk. The model was validated with the damaged buildings in Izmir after the Samos earthquake to capture the buildings with poor performance even under service level earthquakes. The proposed model is practical as it only requires the floor plan and concrete compressive strength. It is found to be legitimately accurate to identify and prioritize the buildings prone to collapse.

Seismic performance of existing buildings constructed before modern seismic design codes is one of the important problems of earthquake prone countries. Increasing life and economic losses after strong earthquakes shows the necessity of seismic performance assessment studies and methods. Therefore, in this study assessment methods recommended by different seismic codes were investigated and probabilistically assessed by comparing the fragility curves of existing low- to mid-rise RC structures. Building performances were determined according to TEC-2007, TBEC-2018, EC8/3 and ASCE 41-17. Eight different occupied buildings, classified according to construction dates (old and new) and story numbers (3 to 6), were selected and investigated by using these codes. At first, building capacity curves and damage limits, defined by the different code methods, were determined via pushover analyses. Structures were then subjected to more than 300 real strong ground motion (GM) records employing nonlinear dynamic analysis and fragility curves were obtained. Static analysis results showed that strength, stiffness and deformation capacity of new buildings are significantly higher than old ones according to all seismic codes considered and it is observed that TBEC-2018 gives the most conservative capacity estimations with respect to others. Comparison of fragility curves indicated that damage probabilities of TBEC-2018 and EC8/3 are higher than other seismic codes and this situation is valid for all story number and building age classes. In most cases TBEC-2018 and TEC-2007 results represent the upper and lower bounds of damage probabilities. It was also found that building age is the most effective parameter that affect the fragilities of existing buildings. Distribution of fragility curves imply that different code methods can give significantly different damage estimations under identical seismic demand levels.

On January 24, 2020, a severe earthquake of magnitude Mw 6.8 hit the Sivrice district of Elazig province at 20:55 (17:55 GMT) local time. This earthquake caused significant damages, partial or total collapses in many buildings with 41 fatalities. A few days after the earthquake, our reconnaissance team visited city centers, districts and villages in the region and, then, carried out an investigation and assessments. The results and suggestions obtained after the earthquakes are very important in designing earthquake-resistant structures and reducing the casualties. This study aims to identify deficiencies and reveal the causes of damages by examining the failure mechanisms of structures. Firstly, the effect of the destructive seismic event is discussed and the historical earthquakes in the region are summarized. Then, strong ground motion data and the structural damages observed from different building types are evaluated. The damage patterns and failure mechanisms are analyzed and interpreted based on the Turkish Earthquake Codes.

Recent earthquakes have shown that the seismic behavior of noncode‐conforming reinforced concrete buildings are in several cases strongly affected by the nonlinear response and possible failure of the beam‐column joints. Beam‐column joint inelasticity is typically due to either shear cracking and failure of the central concrete panel or bond‐slip of the longitudinal steel bars. This paper proposes a new Joint with Hinges macro‐element capable of simulating the most important sources of nonlinearities in the joints. It consists of a quadrilateral central panel whose rigid edges are connected to the beams’ and columns’ end nodes through nonlinear finite‐length interfaces that represent the plastic hinge zones. The central panel deforms in shear only. The joint macro‐element accounts for the nonlinear shear response of the central panel, for the bond‐slip of the longitudinal rebars crossing the joint and for the nonlinear shear and flexural behavior of the plastic hinge zones of the beams and columns connected to the joint. The resulting model of the reinforced concrete frame is the assembly of nonlinear Joint with Hinges macro‐elements connected by elastic frame elements. The proposed formulation is applied in this paper to plane frames. Validation studies with results from available experimental tests on beam‐column joint subassemblages show the proposed model capability to predict the hysteretic responses and the failure mechanisms of connections with unreinforced joints and different beam reinforcement ratios.

In this study, the effects of pounding on seismic behavior of mid-rise reinforced concrete (RC) adjacent buildings with insufficient separation distance were investigated. 5, 8, 10, 13 and 15-storey RC building models were created to represent mid-rise buildings. The nonlinear behavior properties of these models are reflected by plastic hinges defined at the column and beam ends. The buildings are modeled as a three dimensional (3D) column-beam frame system. Adjacent building models are derived, which are connected from floor to floor level using Kelvin contact elements. Total of 30 different adjacent building models were created with the use of buildings having different number of floors. The “0” m gaps reflect inadequate separation distance between adjacent buildings while the “5” m gap is used for the reference building without collision. In order to investigate the pounding effects between adjacent buildings, 22 real acceleration records compatible with TBEC-2018 were selected and scaled. Total of 660 3D nonlinear time history analyses were carried out and the roof displacement demands obtained from these analyses were compared for collision and without collision cases The outcomes of this study show that significant changes may occur in the building displacement demands due to the collision of the mid-rise RC neighboring buildings with insufficient seismic gap. Based on the findings obtained on significant number of adjacent building pairs with different period ratios, the displacement amplification factors (β) are proposed for the mid-rise RC buildings., Bu çalışmada, yetersiz derz mesafesine sahip orta yükseklikteki betonarme komşu binaların sismik etkiler altındaki çekiçleme davranışları incelenmiştir. Orta yükseklikteki binaların temsil edilebilmesi için 5, 8, 10, 13 ve 15 katlı betonarme bina modelleri oluşturulmuştur. Bu modellerin doğrusal elastik olmayan davranış özellikleri kolon ve kiriş uçlarına tanımlanan plastik mafsallar ile yansıtılmıştır. Doğrusal olmayan bina modelleri üç boyutlu (3B) kolonkiriş çerçeve sistemi olarak modellenmiştir. Kelvin birleşim elemanları kullanılarak döşemeden döşemeye bağlanan ikili bina modelleri türetilmiştir. Kat adetleri farklı olan binaların kullanımı ile birlikte toplam 30 adet farklı ikili model oluşturulmuştur. Çarpışmanın görülmediği ikili modellerde 5 m boşluk bırakılırken, çarpışmanın görüldüğü modellerde ise 0 m derz mesafesi seçilmiştir. Bu ikili binalar arasındaki çekiçleme etkilerinin araştırılabilmesi için TBDY-2018 ile uyumlu 22 adet gerçek ivme kaydı seçilerek ölçeklendirilmiştir. Ölçeklendirilen ivme kayıtları 30 adet ikili modele uygulanarak toplam 660 adet zaman tanım alanında dinamik analiz gerçekleştirilmiştir. Analizlerden elde edilen tepe deplasman talepleri, çarpışmalı ve çarpışmasız durumlar için kıyaslanmıştır. Çalışma sonucunda, komşu binaların çarpışması sonucu yapı taleplerinde ciddi değişimler görülmüştür. Komşu binaların periyot oranlarına bağlı olarak çekiçleme etkisi ile değişen yapı talepleri için deplasman büyütme faktörleri (β) önerilmiştir.

Using ETABS software, this study analyzed 23 buildings to evaluate effects of mistakes during construction phase on buildings structural behavior. For modelling, two different loadings were assumed: 1) design loading and 2) loading due to the effects of mistakes in construction phase. Research results determined that considering traditional construction methods for buildings resulted in a significant increase in dead loads and consequently intensified the displacements and base-shears of buildings under seismic loads., {"references":["B. Ellirtgwood, \"Design and Construction Error Effects on Structural\nReliability\", Journal of Structural Engineering, J. Struct. Eng., 113(2),\n1987, 409–422.","A. Doğangün, Ö. Tuluk, R. Livaoğlu, R. Acar, \"Traditional\nwooden buildings and their damages during earthquakes in Turkey\",\nEngineering Failure Analysis, Volume 13, Issue 6, September\n2006, Pages 981-996.","M. Celikag, S. Naimi, \"Building Construction in North Cyprus:\nProblems and Alternatives Solutions\", Procedia Engineering, Volume\n14, 2011, Pages 2269-2275.","O. Kwon, C. Park, C. Lim, \"A defect management system for reinforced\nconcrete work utilizing BIM, image-matching and augmented reality\",\nAutomation in Construction, Volume 46, October 2014, Pages 74-81.","S. O. Ekolu, Y. Ballim, \"Technology transfer to minimize concrete\nconstruction failures\", Proceedings from the International Conference on\nAdvances in Engineering and Technology, 2006, Pages 91-98.","P. Love, R. Lopez, J. Kim, M. Kim, \"Probabilistic Assessment of Design\nError Costs\", Journal of Performance of Constructed Facilities, 28(3),\n(2014). 518-527.","B. Ellingwood, \"Acceptable risk bases for design of structures\",\nProgress in Structural Engineering and Materials, 3(2), 2001, 170-179.","A. Atkinson, \"The role of human error in construction\ndefects\", Structural Survey, 17(4), 1999, 231-236.","M. Stewart, \"Simulation of human error in reinforced concrete design\",\nResearch in Engineering Design, 4(1), 1992, 51-60."]}

Standard engineering procedures, such as adopting high return periods as reference events, are a simplified means of handling the complex and multivariate nature of snow avalanches. Furthermore, such methods do not explicitly take into account the elements at risk and/or possible budgetary constraints. In recent years, many authors from a variety of fields have tried to overcome these limitations with quantitative risk evaluations including cost-benefit analyses. Their proposals are based on different modelling assumptions, and often on different definitions for certain important concepts including scenarios, vulnerability relations and time effects. The first goal of this paper is to propose a state of the art, and to discuss the common points, advantages and drawbacks of the various proposals within a unified formal framework based on decision theory. Most of the applications already in use concern long term risk assessment in land use planning and traffic road regulation, but some potential also exists for short term problems including risk assessment to back-country skiing. In a second time, new extensions of a simple decisional model for the optimal design of an avalanche dam are proposed to illustrate the key point of the place of uncertainty in risk analyses. Finally, to stimulate further research efforts, other important outlooks including computational issues, multivariate optimal design and measures of risk alternative to the standard expected loss minimisation are discussed. (C) 2012 Elsevier B.V. rights reserved.

A parametric model for capacity curves and capacity spectra is proposed. The capacity curve is considered to be composed of a linear part and a nonlinear part. The normalized nonlinear part is modelled bymeans of a cumulative lognormal function. Instead, the cumulative Beta function can be used. Moreover, this new conceptualization of the capacity curves allows defining stiffness and energy functions relative to the total energy loss and stiffness degradation at the ultimate capacity point. Based on these functions, a new damage index is proposed and it is shown that this index, obtained from nonlinear static analysis, is compatible with the Park and Ang index obtained from dynamic analysis. This capacity based damage index allows setting up a fragility model. Specific reinforced concrete buildings are used to illustrate the adequacy of the capacity, damage and fragility models. The usefulness of the models here proposed is highlighted showing how the parametric model is representative for a family of capacity curves having the same normalized nonlinear part and how important variables can be tabulated as empirical functions of the two main parameters defining the capacity model. The availability of this new mathematical model may be a powerful tool for current earthquake engineering research, especially in seismic risk assessments at regional scale and in probabilistic approaches where massive computations are needed.