Proceedings of the 7th International Conference on Earthquake Engineering and Seismology

The earthquake (Mw 6.9) that occurred in the northern part of Samos Island and Doğanbey-İzmir offshore in the Aegean Sea at 14:51 local time on October 30, 2020 was felt in İzmir, Samos Island and many surrounding cities. Considering the earthquake intensity map, contrary to what is expected, the highest impact occurred in Bayraklı district, which is 70 km away from the epicenter, and caused not only severe structural damage but also fatalities in the region. When the structural damages are evaluated, determining the local soil properties has an important place in the studies to predict the effects of a possible earthquake. In this study, it is not only aimed to analyze the earthquake and ambient noise data obtained from the accelerometer and velocity stations but also to compare the results obtained by using HVSR method utilizing different softwares. Furthermore, response spectra were obtained for different local soil classes by using the data of the same stations and they are given in comparison with the design spectra included in the earthquake code. As a result of the study, it has been observed that the results obtained by the HVSR method are in good correlation with the soil effects in the region and the consequential structural damages. These examples illustrate HVSRpy’s commitment to exactly reproduce the results of GEOPSY, wherever the processing parameters and functionality of HVSRpy and GEOPSY overlap. This was done to allow users to check HVSRpy and to encourage standardization in HVSR processing.

Seismic design regulations stipulate the strong-column-weak-beam approach to preclude column yielding during earthquakes. These codes also prescribe the minimums required to withstand seismic demands. However, it is possible to design structures beyond the minimum requirements. This study investigates how longitudinal reinforcement ratio limits influence column-to-beam flexural strength ratios (CBSR), examining the performance of frames with different CBSRs using ground motion records from the 2023 Türkiye earthquakes. Four frames were designed: two with the minimum and maximum possible reinforcement ratios at beams and columns, two with the minimum beam and maximum column reinforcement, and vice versa. The study reveals that the relative strength between the beams and columns significantly affects the extent and distribution of damage. When the beams are too weak compared to the columns, the damage intensifies. On the other hand, having a low overall strength also increases the damage potential. A crucial finding is that moment-frame systems, due to their relatively lower stiffness, faced high drift demands during the 2023 Türkiye earthquakes, leading to severe damage or collapse.

The most dominant type of damage in the February 2023 Kahramanmaras earthquakes was the failure of infills walls. This paper shows just part of the effects of these earthquakes on the infills and concequences on the building inventory and people. The data was collected during the reconaissance field mission one month after the earthquake. In all cities visited damage of the infilled RC frame structures was devastating. Poor behaviour and heavy damage due to the interaction of flexible frames with the stiff infill walls showed that traditional infills (mortar connection between frame and infill) are conceptually wrong system for the buildings in earthquake active areas. Beside heavy in-plane damage, inadequate connection between frames and infills led to the widespread out-of-plane collapse of infill walls. This has jeopardized people and escape routes during the earthquakes as well it produced significant economic loss. Many other earthqukes before showed that this is not acceptable anymore, but this one confirmed it. Therefore, this paper also proposes isolation of infill walls as a solution that can prevent such a devastating effects in future earthqaukes. Although isolation of infills is presribed in the codes it is not in use due to the fact that there are no simple and easy applicable solutions on the market. With the aim to fill this gap, a system presented here is developed. Its goal is to provide functional and easy applicable solution to the designers and construction companies and workers. Experimental tests on the full scale specimens of isolated infilled RC frames are shown, confirming the effectiveness of the isolation system. Infill walls with windows, doors and full walls are tested under various earthquake loading conditions. Furthermore, comparison with the traditional system was done, showing benefits and improvements brought by this system.

After the Kahramanmaraş-centered Mw7.8 and Mw7.6 earthquakes that hit 11 provinces of Türkiye severely on February 6, 2023, it was observed that there are serious problems in the seismic performance of residential buildings and especially the ones with reinforced concrete structural walls. The most important problems observed are the low wall index (the ratio of the total wall area to the floor plan area), i.e. insufficient amount of shear walls placed in the building to resist the earthquake loads in both directions, non-seismic detailing of the rebar lap splices and wall web reinforcement ends, which are only covered with concrete, the inadequacy of wall boundary element confinement reinforcement, unavailable crossties within boundaries and web of structural walls. A parametric study investigated the seismic deformation demands on rectangular wall members in frame-wall systems. The wall index was kept as a variable in frame-wall models, and its relation with the seismic demand at the base of the wall was investigated. 4, 8, and 12-story frame-wall models with wall indexes in the 0.2–2% range were analyzed using nonlinear time-history analysis and design spectrum-matched ground motion set. It was seen that wall boundary concrete compressive strains were much higher than the limits allowed in codes in frame-wall systems with low wall index in the range of 0.2–0.6% indicating to severe damage. It is proposed that in the design of dual systems where beams transfers moments and axial load on walls, the minimum value of the wall index should be greater than 0.6% to prevent excessive damage to wall members.

The southeastern region of Turkey was shaken by two major earthquakes with magnitudes Mw 7.7 and Mw 7.6 on the same day of February 6th, 2023, resulting in extreme destruction and loss of the lives of more than 50,000 people. Among thousands of collapsed buildings, some of the buildings that survived during the first mainshock of Mw 7.7 collapsed or severely damaged after the second mainshock of Mw 7.6 or also after the occurrence of some lower-magnitude aftershocks. This study aims to assess the impact of this earthquake sequence on seismic performance of typical reinforced concrete (RC) building frames, which is the common structural system for residential buildings in Turkey. For this purpose, an analytical study is performed by investigating the seismic response of a 5-story RC building frame with code-conforming and non-code-conforming design features. Nonlinear time-history analyses of the structural models of these frames are conducted in finite element analysis platform OpenSees under the ground motion sequences recorded at five different seismic recording stations in the region. Seismic demand parameter of maximum inter-story drift ratios resulting from each seismic event in a sequence are computed and the influence of stiffness degradation on seismic demands and performance of the frames are assessed for sequential earthquakes. The outcomes of this study are believed to be useful for revealing damage accumulation during such earthquake sequences and the importance of providing adequate reserve capacity for better seismic performances of buildings.

The devastating earthquakes in February 2023 in south-east Türkiye demonstrated that the Turkish built environment does not meet the needed performance. The frequency of earthquakes in Türkiye calls for urgent organization to upgrade the existing structures and avoid the repetition of deficient applications. Hence, it is necessary to identify the causes of the damage. The presented study concentrated on a subset of the existing inventory built under the governance of 1998 and later Turkish Earthquake Codes. Following the earthquakes in Kahramanmaraş, Türkiye, a reconnaissance study was conducted to understand the causes of the damage incurred. The extensive study covered all the major city and town centers, specifically concentrating on the 2- to 16-story reinforced concrete buildings. The first impression of the data gathered indicates significant detailing imperfections. Poor drift control, inferior layout preferences, and non-structural detailing issues are the other suspects. The observed damage and the current seismic regulation requirements will be critically discussed to form a basis for possible future improvements to the seismic code.

Starting with the 1999 Kocaeli Earthquake, seismic damage indices have been developed to quantify damage potential. The late Professor Mete Sozen played a significant role in this endeavor by introducing the Hassan Index, which is an indirect measure of the robustness of structures. Its calculation is straightforward, given the vertical structural element dimensions at ground level. Various earthquakes worldwide, from Taiwan to Chile, have provided opportunities to assess its effectiveness across diverse building practices and earthquake characteristics. Following the February 2023 Kahramanmaraş Earthquakes, a reconnaissance team was dispatched to gather field data to observe the damages through the lens of the Hassan Index. The study extended to cover all major city and town centers, studying around 250 reinforced concrete buildings with 2–16 stories. These buildings were all constructed after the 2000s. Hence, the data set sheds light on the performance of Turkish construction practices after the commencement of the 1998 Turkish Building code and the following earthquake regulations. By evaluating the newly gathered data alongside the existing dataset, a basis is established to consider the Hassan Index as a preliminary design index rather than solely as a seismic damage index.

The 2023 Kahramanmaraş earthquakes (Mw 7.7 Pazarcık and Mw 7.6 Elbistan) struck eleven cities in Türkiye within nine hours. Over 200,000 buildings collapsed or suffered severe damage, while an additional 500,000 had moderate or light damage. Following the earthquakes, the Ministry of Environment, Urbanization, and Climate Change of Türkiye conducted a rapid damage assessment survey over a broad region. The earthquakes were also recorded by a dense network of seismic stations. This study aims to investigate the relationship between the ground motion intensity measures and observed structural damage, utilizing the extensive damage assessment and ground motion data available for various locations in the affected region. Several intensity measures were employed, including effective peak ground acceleration (EPGA) and velocity (PGV), spectral accelerations and displacements for various periods (e.g. Sa0.3, Sa1, Sd0.3, Sd1). These measures were also compared with the design-basis ground motion values provided by the seismic design codes of Türkiye. Notably, the design-basis acceleration and displacement spectra, and code-predicted PGV values were mostly exceeded during the earthquakes, indicating their significance in assessing the damage. These two intensity measures also demonstrated stronger correlations with the observed structural damage compared to other measures. The comparisons with the design-basis values showed that the design spectra should be carefully scrutinized. The findings highlight the importance of a drift-based design approach, which can be based on the expected PGV, instead of a force-based design approach relying on the expected EPGA. Furthermore, this study emphasizes the importance of updating the predictions for PGV considering the consequences of the recent earthquakes.

The devastating earthquakes that struck Kahramanmaraş on February 6, 2023 impacted 11 cities and millions of people in Türkiye, leading to immediate demolition of over 270,000 buildings due to extensive damage or collapse. The aftermath left more than 2 million people facing accommodation issues, underscoring the urgent need to enhance residential building structural performance beyond the standard “life safety performance level”. This study, focusing on reinforced concrete structures, explores the correlation between structural performance and the structural systems of buildings. In the earthquake-affected region, around 90% of buildings utilize reinforced concrete (RC) structural systems. RC moment frames with or without shear walls dominate building construction in Turkey. Besides regular moment frames, wide-beam RC frames with thin slabs and one-way joists are also common. The current seismic design code allows these systems if adequate shear walls are provided, but it is observed that some recently constructed buildings violate this requirement. Both types of structural systems experienced damage during the earthquakes. A less frequent building type was shear-wall buildings, which rely solely on shear walls for lateral-load resistance. It was observed that the buildings with evenly distributed shear walls in both plan directions exhibited robust seismic performance if these wall amounts were sufficient compared to their height. Otherwise, these buildings suffered heavy structural damage. The findings of this study stress the need for a comprehensive assessment of structural systems to enhance earthquake performance and ensure the safety of lives and property in seismic regions.

On February 6th, 2023, East Anatolian Fault system in Turkiye caused a severe earthquake sequence with moment magnitudes (Mw) of 7.7 and 7.6 at the epicenter of Kahramanmaras, affecting 11 provinces and a significant portion of Turkey’s industrial community. A reconnaissance team was assembled in the days following the earthquake sequence to visit the industrial districts in the five provinces of the affected area: Adana, Osmaniye, Kahramanmaras, Gaziantep, Iskenderun, and Hatay. While the performance and functionality of 131 industrial buildings (59 precast reinforced concrete buildings) were inspected using the proposed data-collection protocols, several semi-structured interviews with industrial representatives were conducted to gather information on industrial buildings’ damage and functionality states. The inspections and interviews established that the earthquake sequence had a severe impact on industrial buildings, resulting in substantial financial losses and long-term business interruptions. Precast concrete industrial buildings built before 2000 were found to be particularly vulnerable. The connection failures between columns and beams were the most widespread damage cause. Empirical fragility curves connecting seismic demands to the performance (structural and non-structural) and functionality states of the inspected precast reinforced concrete industrial buildings were derived based on the post-earthquake damage data collected during the reconnaissance mission. The field observations and proposed fragility models will be a step towards resilient industrial buildings in Turkiye.

On February 6, 2023, at 04.17 and 13.24 local time in Turkey, two earthquakes with an instrumental magnitude (Mw) of 7.7 and 7.6 with epicenters in Pazarcık (Kahramanmaraş) and Elbistan (Kahramanmaraş) occurred 9 h apart. It caused great destruction, damage, and many casualties in Adıyaman and neighboring provinces. This study aims to compare the probabilistic earthquake hazard assessment (PSHA) with the scenario-based deterministic seismic hazard assessment (DSHA) for Adıyaman. The impact of both earthquakes on Adıyaman province was analyzed deterministically using OpenQuake software. Scenario-based analysis is performed by using the earthquake information such as magnitude, longitude, latitude, dip angle, and rake angle and Chiou and Youngs 2014 attenuation relationship, by taking into account the soil conditions in the region. Earthquake intensity distribution were evaluated. The intensity distribution on Adıyaman derived from scenario analysis is compared with PSHA results. Based on PSHA results for 475 and 2475 years return period ground motion level of approximately 0.6 g and 0.8 g PGA level is predicted, respectively at the center of the Adıyaman. PGA value at the center of the Adıyaman for the Pazarcık and Elbistan earthquakes are calculated as 0.8 g and 0.7 g respectively, through scenario analysis of both earthquakes. Site-specific scenario-based DSHA analysis is in good agreement with PSHA results from the ESHM20 model. The computational results from this study can help provide a reference for seismic hazard assessment around any region under any probable earthquake scenario. DSHA results will be used to compare observed damage and predicted damage around Adıyaman.

Vs30 is an important field parameter in determining the intensity of ground shaking and characterizing local soil conditions for estimating site effects to determine seismic hazards. Given the critical need for acquiring Vs30 values, particularly in a digital format and on a grid scale, a comprehensive study to estimate Vs30 all across Türkiye has become essential. Therefore, in this study, relationships between Vs30, geological and topographical data have been investigated, and empirical equations to estimate Vs30 values have been established. These relationships have been developed based on data obtained from the digital geological and digital topographic elevation maps (MERIT-DEM), and Vs30 measurements near the vicinity of strong ground motion stations all across Türkiye. Units in digital geological maps were initially regrouped into classes based on geological periods. The correlations between these classes and the Vs30 samples were interpreted to determine the limits of each class. Secondly, topographic parameters were calculated with 2D trend surface analysis methods to be used in Vs30 predictions. The topographical parameters were correlated with Vs30 utilizing the least-squares method, resulting in the generation of equations for estimating Vs30 for each geological category (R2: 0.601). In addition, the coefficients of the envelope curve corresponding to a given exceedance probability (p) for the worst-case scenario were determined using the quantile regression method. Consequently, digitized maps of the Vs30 estimations were produced in a raster format that can be queried in a GIS environment.

Earthquakes are natural events that cause damage to built environments by the instant seismic energy release. This energy is measured by instrumental devices to obtain the peak ground motion parameters such as Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV). Additional measurements based on the questionnaires after the earthquakes are required to identify the felt or macro seismic intensity levels. These measurements are crucial to identify the total effects of earthquakes over not only an area but also for the spatial distribution of ground motion parameters. For this purpose, it is important to study the multi-variable criteria correlations between ground motion parameters and Modified Mercalli Intensity (MMI) levels based on linear relationships of predictor variable couples. In this regard, the Multivariate Adaptive Regression Splines (MARS) Method and the Multiple Linear Regression Method are used. The entire dataset is composed of 69 earthquakes between 2005 and 2022 with 2171 ground motion parameters coupled with MMI levels. For MMI-based correlations, the MARS method is used to identify the non-linearities between predictor variables by piecewise linear functions, but for the Multiple Linear Regression Method, the least correlated variables of PGA-Epicentral Distance and PGV-Epicentral Distance are used to obtain the relationship between MMI and PGM parameters. The resulting equations obtained for the entire Türkiye database are performed to identify MMI maps of the 6th of February 2023, Kahramanmaraş Earthquakes, and these maps are used to check the accuracy of the results by the comparison of field survey-based MMI maps. Finally, the numerical MMI maps are found to be consistent with the field survey-based MMI maps.

Seismograms from 71 ground motion stations within 100 km of the fault rupture were used to investigate the durational variability observed during the February 6, 2023, M7.8 Türkiye-Kahramanmaraş-Pazarcık earthquake. The duration parameters estimated from the recordings and predicted by Tafreshi and Bora (Bull Earthq Eng 21:4139–4166, 2023) and Cetin et al. (Soil Dyn Earthq Eng 143, 2021) models were compared. The results showed significant differences between the duration parameters estimated from the recordings and the predictive equations for the cities of Hatay and Malatya. Hatay, located on forward directivity and fault rupture paths, experienced shorter duration and higher intensity levels. Kahramanmaraş, Adana, Osmaniye, Diyarbakır, and Elazığ cities experienced slightly longer significant durations than predicted. The overall mean residuals for stations on the Anatolian and Arabian plate sides of the fault rupture plane were estimated as −0.02 ± 0.54 and 0.37 ± 0.33, respectively. Residuals increased slightly with increasing rupture distances, more pronounced for significant duration. Site conditions did not significantly affect durational variability. A stronger dependency of inter-event residuals on azimuth angle θ was estimated, with residuals negative for θ < 5 degrees and positive for θ beyond 5 degrees. This observation confirmed the effects of directivity and/or rupture propagation velocity on the duration of seismic shaking during the Kahramanmaraş-Pazarcık event.

This paper draws attention to apparent discord between spectra from actual recordings at a number of stations of the national strong motion network of Turkey with the design spectra for the same location and site characteristics. We find that, for deep basins with Site Class D or E profiles, the design spectrum seems not to recognize consistently the constant velocity and longer period demand. If this conjecture is true, it may foreshadow unsafe designs for the building stock in Turkey in similar environments. The recently recorded strong ground motion records from the 06 February 2023, M 7.7 and M 7.5 Kahramanmaraş, earthquakes support the conjecture of this study and provide evidence for a need to revise the corner periods of the design spectrum in the Regulation.

In this study, an adaptive modal pushover analysis procedure (VMPA-A) is implemented in the 20-story Los Angeles SAC Steel building. The method considers the changes in the dynamic characteristics and bi-directional ground motion effects simultaneously with the help of the hybrid-spectrum concept. Two different approaches are used to calculate displacement demands for each mode. The first one is equal displacement rule and the second is performing nonlinear time history analyses (NTHA) to modal single degree of freedom systems (SDOF). VMPA-A procedure is implemented by using a MATLAB-based computer program, DOC3D. The building is modeled with both SAP2000 and DOC3D programs. Cross-checks are done between two programs by performing eigenvalue and pushover analyses. As an accepted “exact solution”, NTHAs are used to check the accuracy of the VMPA-A procedure. Fourteen ground motion records, which were selected from the PEER NGA-West2 Database, are used in NTHAs by using SAP2000. The response parameters of storey shears, storey displacements, storey drifts, and column and beam curvatures are discussed by comparing the results of VMPA-A with nonlinear time history analyses. Good estimates are observed for storey displacements, storey shears, and storey drifts. Although the second approach in the calculation of displacement demands gives closer results to NTHA, the obtained demand parameters from the equal displacement rule are conservative. Storey drift and beam curvature distributions seem to be in a similar trend. Larger values for lower stories and smaller values for the upper stories are obtained with respect to the average of NTHAs. However, beam curvature distribution can not be predicted by VMPA-A, especially for the upper stories of the building. The column curvature results are in good agreement with NTHA results.

A common lateral force resisting system for cold-formed steel (CFS) structures in seismic areas consists of Shear Walls Panel (SWP) sheathed with trapezoidal steel sheets. Under lateral load, the global response and several failure modes have been manifesting and are still attracting designers’ and researchers’ attention. The present work put forward a sufficiently detailed numerical analysis of the global response of CFS-SWP with trapezoidal steel sheathing. A Finite Element (FE) modeling is developed using the ABAQUS software, taking into account material and geometrical nonlinearities, as well as assembled sheathing-to-framing connections. Monotonic pushover loading is imposed on the CFS-SWP and general static nonlinear analyses are performed. The results of the FE modeling are validated with available experimental data, and a good agreement is achieved, namely: nonlinear strength-displacements response, ultimate shear strength and corresponding displacements, and initial stiffness. Moreover, the shear strength capacity of the trapezoidal SWP with different lengths, out of the AISI S400-15 configurations is evaluated through a parametric study and presented to engineers and designers. In addition, the developed FE modeling can be used to simulate and evaluate the shear strength of steel trapezoidal CFS shear wall panels with other mechanical and geometrics characteristics.

In Turkey, with seismic risk mitigation programs, structural strengthening and reconstruction of existing building-type structures have been brought into consideration, the need to scan and prioritize structures in facilities, districts or cities has arisen. In order to prioritize the structures in the region of interest, to prepare a disaster plan and to estimate the economic impacts of a possible earthquake; examining building plans, developing three-dimensional mathematical modeling and performing non-linear push-over analysis are required. As the amount of work involved, the demand for technical personnel and the cost of application are excessive for conducting screening studies, new statistical methods have been introduced throughout the world. In the United States, with the goal of estimating the economic impacts of the big California earthquake, studies in this field accelerated with ATC-13 in 1985 and advanced further with Hazus methodology by 1997. In this study, statistical building capacity curves of the Hazus-MH4.2 (2020) methodology, were used and the nonlinear building capacity curve parameters of concrete moment-frame type structures built according to different design levels, the most common building types in Turkey, were calculated with Hazus methodology. In addition, 3D mathematical models of these structures were created and nonlinear pushover analyzes were performed. Building capacity curve parameters calculated from the nonlinear push-over analysis and Hazus methodology were then compared and interpreted. Lastly, in light of the results obtained, whether the current Hazes methodology is fit for concrete moment frame type structures built according to Pre-Code, Low-Code, Moderate-Code, and High-Code in Turkey was discussed.

Electric power is crucial during the aftermath of earthquakes to ensure the continuous operation of disaster management and emergency services. Furthermore, any disruption in electrical power can result in significant economic losses due to the downtime of critical facilities. Hence, it is of utmost importance to maintain the seismic safety of electrical power systems and their components. Seismic regulations and standards already exist for electrical power systems, particularly in the United States of America (USA) and Europe. Similarly, Turkey has recently developed a similar regulation set to take effect in 2024. This study focuses on the current practices related to assessing the seismic suitability of electrical equipment in power stations and implementing the regulations for seismic qualification of these systems. Among the various electrical equipment, circuit breaker has been chosen for case study. The seismic assessment of the selected high voltage equipment has been conducted according to the new regulation under the seismic hazard specifically defined for Turkey. The case study demonstrates a novel approach to assessing and categorizing the seismic response of high-voltage electrical equipment, offering insights into how circuit breakers are expected to behave when subjected to earthquake-induced forces.

In this comprehensive study, the seismic response of single-story asymmetric systems with three degrees of freedom is thoroughly evaluated. The structures under investigation exhibit diverse torsional characteristics, ranging from torsionally stiff to flexible systems. Classification of torsional characteristics relies on indicators such as modal participation factors and uncoupled frequency ratios. Nonlinear dynamic analyses are performed under bi-axial ground motion pairs. Major findings indicate that systems initially classified as torsionally flexible exhibit torsionally stiff nonlinear behavior characteristics in terms of displacement demand distribution. In the case of torsionally stiff systems, it is determined that nonlinear action does not substantially alter demand distribution. Torsionally stiff behavior remains essentially unchanged even in high levels of nonlinearity during the bi-axial response history analyses. The outcomes of the study not only yield essential insights into the seismic behavior of single-story asymmetric systems but also highlight the intricate influence of torsional characteristics on their dynamic response.

In earthquake engineering, the selection and scaling of earthquake records are indispensable for determining the performance of structures. In this study, two different methods were compared, and an interface was started to develop to implement the process in a user-friendly way. Two different scaling methods were compared to evaluate their effects on the seismic performance of the 5-story building by using the same dynamic characteristics of the structure. In the first method, the spectrum averages of all earthquake records were scaled to the design spectrum in the determined period range. All earthquake records were then multiplied by a single coefficient. In the second method, each earthquake record was scaled with the design spectrum in the determined period range, and different scaling coefficients were used for each earthquake record. The results pointed out significant differences in the displacement and relative story drift ratios of the structures due to the scaling methods used. In order to obtain more robust and generalizable results, repeated analyses should be conducted using different earthquake sets and multiple structures. The findings obtained as a result of the study have important implications for the performance-based design of reinforced concrete buildings in seismic zones, highlighting the need for more advanced and accurate scaling methods in seismic analysis. The development of computational tools, such as the Python application used in this study, may also play a crucial role in improving the efficiency and reliability of future seismic analyses.

The Forest of Steles at the Great South Gate is the first stele forest in Taiwan, with seven of the steles being first-class historical monuments. The building is a one-story RC structure composed of columns and rectangular beams. On September 18, 2022, a 6.8 magnitude earthquake occurred in Taiwan, causing significant cracks in the columns. Upon investigation, it was found that most of the cracks occurred at both ends of the columns. It was determined that the cause of the cracks was insufficient flexural capacity at the ends of the columns. In this project, the current capacity curve of the building was analyzed using the Taiwan Earthquake Assessment for Structures by Pushover Analysis (TEASPA3.0). The result showed that the Capacity to Demand Ratio (CDR) of the building was only 0.633, indicating the need for seismic retrofitting of the building. The retrofitting analysis was based on TEASPA3.0 and combined with the UHPC auxiliary analysis program developed by National Cheng Kung University to obtain the capacity curve after retrofitting. The CDR of the building after retrofitting was 1.104. Compared with traditional concrete, Ultra-High Performance Concrete (UHPC) has a flexural strength that is more than five times higher. Its mechanical properties can effectively reduce the strengthened section compared with the traditional methods, thus maintaining the original size of the column. This method is the first practical application of seismic retrofitting with UHPC in Taiwan.

Evaluation of existing structures under earthquake loads has an important place in the field of performance-based earthquake engineering. In this respect, linear and non-linear analysis methods can be used in the evaluation of existing structures. Analysis procedures and condition assessment methods for existing structures are thoroughly explained in the Turkish Building Earthquake Code (TBEC-2018). The linear elastic method, which is unique to TBEC-2018, is based on demand parameters of structural elements such as chord rotations and section curvatures. Plastic rotation demands can be calculated using the linear elastic force–deformation relationships and the seismic performance of the structure can be evaluated on the basis of these computed demands. In the scope of this study, the parameters which are used in the application of the linear elastic assessment method are studied. Seismic performance evaluation of an existing school building is carried out using the TBEC-2018 linear elastic assessment procedure. A retrofit project is prepared for the school building and its seismic performance is assessed, as well. Obtained results are then compared with those compiled from the nonlinear dynamic analyses. The comparative investigation reveals that the TBEC-2018 linear elastic assessment procedure is generally successful in estimating the global seismic response as well as individual member plastic rotation demands of the inspected school building.

This research explores the impact of ageing effects resulting from the corrosion of structural materials on fragility functions which are analytically derived for reinforced concrete moment-resisting frame buildings. These structures represent the predominant architectural typology in Türkiye. Initially, an examination is conducted on both in-situ and laboratory material testing results obtained from reinforced concrete buildings in Istanbul. These buildings were constructed between 1962 and 2004. The objective is to gain deeper insights into the extent of corrosion and its distribution within structural components. Subsequently, the degree of corrosion and its diverse manifestations are integrated into structural analyses. This is achieved by modifying the mechanical properties and constitutive models of materials using data acquired from literature-based experimental and numerical findings. To accomplish this, three-dimensional finite element models are developed for both low- and mid-rise buildings. These models adhere to the guidelines outlined in the 1975, 1997, and 2018 Turkish earthquake codes. The comprehensive analysis takes place within the OpenSees environment. The behavior of buildings in their original state and as they age is investigated using nonlinear dynamic analyses. These analyses subject the structures to strong ground motion accelerations which are chosen and scaled to accurately represent the seismic hazard level specific to Istanbul. In the process of deriving fragility functions, the study employs techniques such as multiple-stripe analysis and maximum likelihood estimation method. These methodologies contribute to a robust understanding of the vulnerability of the structures under consideration.

It is an important issue that earthquake characteristics and engineering intensity parameters can be determined quickly and practically to be used in earthquake engineering applications in the light of new developing technologies. Within this context, an increase is observed in software integration of engineering parameters. In this study, using Python software language, maximum acceleration (PGA), maximum velocity (PGV), and maximum displacement (PGD) values were calculated from time series records of strong ground motions of a certain earthquake; velocity-acceleration-displacement time series of records were produced; response spectra were visualized by comparing them with the design spectra defined in the Turkish Building Earthquake Code (TBDY-2018). Frequency contents of earthquake signals were also obtained (Fourier Amplitude—Frequency plots). It is aimed to provide ease of interpretation by visualizing the outputs obtained. With the help of the open-source software DARLA (ver1.0), which was developed within the scope of this study, it is intended to make a rapid assessment in the light of semi-automatically produced scientific data, in terms of earthquake engineering, specific to the region, from the moment the earthquake occurred.

Dual structural systems (moment resisting frame with RC structural walls) are common in mid and high-rise buildings due to their better performances in past earthquakes. The seismic behaviour of RC structural walls (commonly known as shear walls) having rectangular cross-sectional shapes has been studied extensively in past decades but the study on the behaviour of flanged RC walls is relatively limited. In this study, the seismic behaviour of flanged (T-shaped) RC walls and rectangular RC walls with different grades of reinforcement have been compared using nonlinear finite element analysis. The numerical simulations have been carried out using the software ABAQUS. The Concrete Damage Plasticity (CDP) model is employed as the constitutive model in the case of concrete. In the case of steel reinforcement bars, the experimental stress–strain curves of two types of rebar having theoretical yield values of 600 MPa (ductile) and 500 MPa (non-ductile) are used instead of any prescribed idealised model. It is observed that the yield drift for the RC wall built with high-strength (fy = 600 MPa) ductile reinforcement is significantly higher as compared to the wall with normal-strength (fy = 500 MPa) reinforcement. On the other hand, it is found that the influence of the different types of reinforcement on the ultimate drift of the RC wall depends on the nature of the corresponding failure mode.

This paper proposes an integrated framework, specifically calibrated and demonstrated for the Italian residential building stock, applicable to any other region or country, for regional-based prioritization of residential buildings for seismic and energy efficiency performance upgrading. The framework encompasses single and multi-sectoral indicators, estimated according to state-of-the-art engineering-based research, providing different prioritization patterns at national scale. The most recent building fragility models for Italy are selected and combined through a logic tree strategy. The space heating energy consumption and CO2 emissions are directly taken from a collection of all the Energy Performance Certificates (APE) of Italian buildings and building units, while national and European indices are used to account for socioeconomic aspects. The proposed framework and the prioritization patterns obtained in this work can support relevant stakeholders to foresee economic support and strategic financial planning for seismic strengthening and energy renovation interventions on existing buildings, including socioeconomic features, and favor funding in regions of higher needs.

Traditional masonry constructions are extremely vulnerable to seismic events, affecting the development of many countries around the world. The out-of-plane (OOP) seismic response of masonry walls is one of the most complex and ill-understood areas of seismic analysis. Post-earthquake observations have identified OOP collapse as one of the main failure modes in unreinforced masonry buildings (URM) and most of these occur due to inadequate design or construction. Furthermore, even though current seismic safety assessment codes emphasize the use of nonlinear analysis methods, most professionals still rely on linear-elastic analysis due to its simplicity. The present work contributes to the seismic safety assessment of the out-of-plane behavior of unreinforced masonry walls through a displacement-based approach, providing the capacity for different out-of-plane geometric indexes and its seismic response in different earthquake-prone regions in Europe. The analyses are conducted using a seismic probabilistic framework, considering the most common out-of-plane mechanisms, different material properties, various slenderness ratios, and a wide range of seismicity levels to cover the seismic hazard in Europe. The results presented can be useful for seismic safety assessment by providing simple relationships to compute the capacity and the seismic demand in compliance with the seismic action in the European standard.

Masonry structures are found in almost every region of our country, depending on the availability of construction materials. Behavior of wall-bearing masonry structures under horizontal loads, especially earthquakes, differs significantly from that of conventional reinforced concrete frame structures. Therefore, masonry structures are either included in seismic codes as an individual section or special regulations about this construction type are published. In this study, the previously enacted 1975, 1998, and 2007 codes, as well as the new seismic code, which came into force in 2019, have been compared and analyzed on a sample masonry building. Since the 2019 earthquake code did not have the concept of seismic zones, three different locations (Region 01, Region 02, and Region 03) are selected from seismic zones 1, 2, 3, and 4, based on previous earthquake codes, in order to make a comparison. Results from a masonry building sample built in Region 01 (Bingöl-Karlıova) show that the highest base shear force is calculated using the 2019 code for the first seismic zone. However, for Regions 02 (İzmir-Menemen) and 03 (Çanakkale-Biga), the highest base shear force is calculated by using the 2007 code for the same seismic zone. Similar results were obtained for other seismic zones. It is worth noting that the 1975 earthquake code produced the lowest values of design force among all the codes.

Nonlinear dynamic analysis is becoming increasingly common in practical engineering, especially in the seismic assessment and design of structural systems. The seismic design codes require selecting and scaling the earthquake ground motion data concerning a target response spectrum for the dynamic analyses. In the 2018 Turkish Building Earthquake Code, earthquake ground motions are selected considering the magnitude, distance to fault, shear wave velocity of soil (VS30), and fault types of ground motions. In this study, a new algorithm is evaluated for selecting the ground motion records by accounting for the ductility ratio of the structural systems. The evaluated algorithm considers the structural ductility along with the magnitude, distance to fault, VS30, and fault type in selecting the ground motion. Moreover, the efficiency of the ductility ratio algorithm and maximum inter-story drift in the SDOF system is compared by the ground motion record sets selected and scaled concerning Conditional Mean Spectrum (CMS) and Turkish Building Earthquake Code 2018 (TBEC-2018). The efficiency of matching the mean of the response spectra of the selected ground motion record sets with the target spectrum was examined by considering diverse structural ductility cases.

The seismic capacity and response of unreinforced infill walls have been ignored until realizing the importance of these members during many seismic events and their aftermaths. The performed study aims to obtain seismic behavior of infill walls in the out-of-plane direction. Fort this, an experimental study including 8 infill wall tests was conducted. The out-of-plane capacity of the unreinforced masonry infill walls with different opening sizes were investigated by using two different infill materials; clay brick blocks, and pumice concrete blocks. The presence and the size of the openings were chosen as the test parameters in addition to the infill materials. The infill walls with window opening, door opening and without opening were simulated by using a half-scaled RC frame. Additionally, lintels were used for each infill walls with opening. After conducting 8 unreinforced infill wall specimens which include 5 clay brick infill walls and 3 pumice concrete infill walls under out-of-plane loading it was noticed that the infill walls with the door openings had the least load carrying capacity while the window opening simulated infill walls have the highest load carrying capacity for both infill materials under out-of-plane loading. Moreover, it was observed that the construction direction of the clay brick blocks affects the load carrying capacity in the out of plane direction. Another observation is that the infill wall specimens with pumice concrete have higher load carrying capacity than the infill wall specimens with the traditional clay bricks for all kind of infill walls.

In engineering practice in Türkiye, there are three main codes employed for bridge design which are AASHTO LRFD Design Specifications for Bridge Design, Eurocodes and Turkish Earthquake Specification for Bridges. These codes have different seismic design criteria for the selection of ground motion records and design response spectra used in analysis. In this study, influence of ground motion scaling method on response of bridges is evaluated through linear time history analysis. For this purpose, three bridges representing short-, medium-, and long-period bridges are selected in Istanbul that lay near the Northern Anatolia Fault. Three scaling methods are employed to study the effect of scaling methods. The first method is to scale the ground motion records with one factor according to the mean spectrum of selected earthquakes. The second and third methods are to scale each ground motion record separately. No upper limits for the scale factors are introduced for the second method, while for the third method upper limit of 2 is assigned. Besides, to comprehend the importance of the selection of ground motion sets, three different sets, each having seven ground motion records, are formed. Analyses results like column moments and displacements under the selected and scaled ground motion sets are compared. The results indicated that the scaling methods and ground motion sets for the bridges having different fundamental periods do not have consistent results. It has been observed that, in general, the influence of ground motion set becomes insignificant as the period of the structure gets smaller. As a general conclusion, it appeared that no generalization can be made regarding the selection of a ground motion record set and scaling method for the studied bridges. It is suggested that various methods and ground motion sets should be employed to conduct a correct time history analysis and to meet the seismic demands of a specific structure.

In this study, design approaches used for the seismic design of non-structural components subjected to earthquakes are compared according to the Turkish Building Earthquake Code 2018 (TBEC 2018) and the ASCE/SEI 7-22 Minimum Design Loads for Buildings and Other Structures standard. In the scope of this study, a school building designed in accordance with TBEC 2018 has been modeled. After the analyses of the school building structure, seismic forces acting on an imaginary generator as an example non-structural component were determined using equivalent seismic load and nonlinear time history methods specified in TBEC 2018 and ASCE/SEI 7-22. A parametric study was conducted for this component, considering different floors, and all results were compared with tables and charts. In addition, raised floor shake table tests were conducted at the ITU Structural and Earthquake Engineering Laboratory. The design forces obtained from the relevant codes were compared with the experimental results to confirm their consistency.

In recent years, there has been a significant increase in the number of residential and commercial buildings. This significant increase requires much attention to the effects of earthquake loads on structural systems and the resistance of structures against seismic forces. Structural systems are subjected to large lateral displacement due to seismic effects. Reinforced concrete shear wall buildings that are a popular choice in many earthquakes prone countries resist large earthquake loads and support gravity loads and also prevent large lateral displacements. Reinforced concrete shear walls are widely used in these structural systems to provide appropriate strength and stiffness to resist lateral displacements caused by earthquake loads. Shear wall generally gives better response to earthquake loads when it is provided at an effective location of the building plan. Therefore, positioning of shear wall has evident influence on the overall behavior of the building. Main objective of this study is to examine the actual behavior of shear wall for different locations. For this purpose, nonlinear static analysis has been performed for three different positioning of RC shear wall designed according to Turkish Seismic Code (TSC-2018). The sample buildings have 8-storey with columns, beams, slabs, and RC shear walls. The RC shear walls have same length and width for three different cases, so the results are affected by the arrangement and positioning of RC shear walls only.

Buried steel pipelines crossing active fault zones are vulnerable to severe damage under strike-slip fault actions, hence proper understanding and estimation of their mechanical behavior under such geohazards is of paramount importance. This study presents a simplified semi-analytical–numerical response analysis approach for buries steel pipes making use of iterative solution method relying on the need of compatibility among the available and geometrically required pipeline deformation under the applied fault load to compute the pipe bending angle (θ). Simplified numerical analysis models capable of capturing the complex nature of the problem through the use of distributed plasticity models were used to determine the tensile strains (εT) on the pipe developing under the fault load simulated as incremental displacement. Curve fitting techniques were then used to determine the relationship between the bending angle (θ) and computed strains (εT). A series of analyses performed using the developed approach, considering three fault intersection angle (β) values (10°, 15°, and 30°) and three pipe diameter to wall thickness (D/t) ratios (58, 96, and 144) as design parameters, revealed the existence of exponential relationships between the angle θ and pipe tensile strains. Maximum strain values computed using the proposed method were lastly compared with results obtained through the solution of rigorious numerical models developed using ABAQUS FE analysis software to verify the accuracy of the method. A good overall agreement was determined to exist between the two solution approaches for all cases investigated.

Machine learning techniques have gained significant popularity within earthquake engineering for constructing predictive models to understand how structures will behave during seismic events. These models often employ complex methodologies to attain a high level of accuracy in decision-making. However, the comprehensibility of such predictive models is just as crucial as their accuracy. Engineers require insight into the model’s decision-making process to ensure its practicality. This research strives to simultaneously achieve both transparency and precision, introducing an intelligible classification model designed to forecast the potential seismic failure mode of reinforced concrete shear walls. To accomplish this, eight distinct machine learning methods are utilized where experimental failure modes of conventional shear walls were used and designated as outputs, whereas wall design parameters such as compressive strength of concrete, axial load ratio, etc. were used as the inputs (features). The findings reveal that the Decision Tree approach emerges as the most suitable classifier, effectively delivering both high classification accuracy and interpretability.

This paper aims to analyze the behavior of experimentally tested unreinforced masonry walls subjected to in-plane loading. Monotonic load analyses are conducted using FEM and AEM modeling approaches. The models presented here are based on the assumption of both unit and mortar joints modeled as solid elements, which behave nonlinearly. Therefore, the damages occur along the mortar and brick in the analyses. The FEM analysis is carried out by using LS-DYNA, and the AEM analysis is carried out by using ELS (Extreme Loading for Structures). Experimental studies of a masonry wall in-plane loading conditions are used for verification against numerical models. Analysis of the tests performed on masonry shear walls by Raijmakers and Vermeltfoort [1] within the CUR [2] project is carried out. The presented analyses methods can be applied to other unit and mortar compositions. Computational results from this study provide a monotonic load-deformation curve, which then is compared to the envelope of the horizontal load-deformation curves that are experimentally obtained. The agreement of each method with the experimental results, in terms of strength, stiffness and ductility, as well as the predicted damage mechanisms, are discussed.

Storage tanks are structures widely used in industrial facilities for storing products such as oil, petroleum, and chemical liquids. Ensuring the protection of flammable and hazardous materials in these tanks during events like earthquakes and tsunamis is of utmost importance. Otherwise, even a minor external impact can lead to leakage, spills, or overflow of the liquid, which can easily ignite and result in larger disasters such as fires and explosions. Numerous instances of such incidents have been witnessed worldwide during past earthquakes. Therefore, it is crucial to thoroughly analyse the seismic behaviour of these structures and carefully design them to be earthquake resistant. In this study, the behaviour of horizontal cylindrical liquid storage tanks under the effect of various earthquake records was examined, and calculations were performed for the anchors in the supporting saddles. Furthermore, the damage observed in vertical cylindrical storage tanks during the Kahramanmaras earthquakes on February 6, 2023, was investigated, and analytical studies using finite element modelling demonstrated the ability to simulate the observed damage. This outcome highlights the effectiveness of the conducted finite element analyses in obtaining results that closely resemble reality.

During the design phase of the structures, all calculations and processes can be carried out in accordance with the rules by expert engineers. There exist comprehensive structural codes which refer to the importance of adhering to the relevant standards for assuring concrete quality and, standards for concrete in turn, prescriptively define the rules for the high-quality concrete and its constituents. However, recent earthquakes have proved that when inspection during the construction phase and concrete production is ignored, the structure would not be earthquake resistant. In order to assure the quality of earthquake resistant structures, pre-testing and testing during the production phase should be implemented. Inspection sections for materials is an essential tool for the quality assessment of the constituents for concrete. Workmanship and equipment quality should be assessed during the full-scale trial tests. Effective specifications, quality and inspection test plans are required in the production phase. These will allow for quick responses and provide solutions by the engineers for the material related problems during the production phase.

Examining soil-structure interaction (SSI) stands as a crucial factor impacting a structure’s performance during an earthquake. The interplay between a building’s foundation and the underlying soil holds the potential to significantly influence its dynamic response. Neglecting SSI can result in overly cautious or impractical retrofitting designs. This research delves into the seismic retrofitting of 5 and 7-story 2D reinforced concrete (RC) frames employing the Resilient Slip Friction Joint (RSFJ), with a primary emphasis on addressing Soil-Structure Interaction and the seismic response under earthquake excitation resembling Pulse-like ground motions. The structural model is constructed using Finite Element Method (FEM) software, specifically OpenSeesPy, which incorporates SSI into the analysis. The study aims to shed light on the nonlinear dynamic behavior of buildings of varying heights, particularly 5 and 7 stories, when they undergo retrofitting with RSFJ, while taking into consideration the influence of SSI.