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Background Prognostic assessments of the mortality of critically ill patients are frequently performed in daily clinical practice and provide prognostic guidance in treatment decisions. In contrast to several sophisticated tools, prognostic estimations made by healthcare providers are always available and accessible, are performed daily, and might have an additive value to guide clinical decision-making. The aim of this study was to evaluate the accuracy of students’, nurses’, and physicians’ estimations and the association of their combined estimations with in-hospital mortality and 6-month follow-up. Methods The Simple Observational Critical Care Studies is a prospective observational single-center study in a tertiary teaching hospital in the Netherlands. All patients acutely admitted to the intensive care unit were included. Within 3 h of admission to the intensive care unit, a medical or nursing student, a nurse, and a physician independently predicted in-hospital and 6-month mortality. Logistic regression was used to assess the associations between predictions and the actual outcome; the area under the receiver operating characteristics (AUROC) was calculated to estimate the discriminative accuracy of the students, nurses, and physicians. Results In 827 out of 1,010 patients, in-hospital mortality rates were predicted to be 11%, 15%, and 17% by medical students, nurses, and physicians, respectively. The estimations of students, nurses, and physicians were all associated with in-hospital mortality (OR 5.8, 95% CI [3.7, 9.2], OR 4.7, 95% CI [3.0, 7.3], and OR 7.7 95% CI [4.7, 12.8], respectively). Discriminative accuracy was moderate for all students, nurses, and physicians (between 0.58 and 0.68). When more estimations were of non-survival, the odds of non-survival increased (OR 2.4 95% CI [1.9, 3.1]) per additional estimate, AUROC 0.70 (0.65, 0.76). For 6-month mortality predictions, similar results were observed. Conclusions Based on the initial examination, students, nurses, and physicians can only moderately predict in-hospital and 6-month mortality in critically ill patients. Combined estimations led to more accurate predictions and may serve as an example of the benefit of multidisciplinary clinical care and future research efforts.

This paper presents a proof of concept for monitoring masonry structures using two different types of markers which are not easily noticeable by human eye but exhibit high reflection when subjected to NIR (near-infrared) wavelength of light. The first type is a retroreflective marker covered by a special tape that is opaque in visible light but translucent in NIR, while the second marker is a paint produced from infrared reflective pigments. The reflection of these markers is captured by a special camera-flash combination and processed using image processing algorithms. A series of experiments were conducted to verify their potential to monitor crack development. It is shown that the difference between the actual crack width and the measured was satisfactorily small. Besides that, the painted markers perform better than the tape markers both in terms of accuracy and precision, while their accuracy could be in the range of 0.05 mm which verifies its potential to be used for measuring cracks in masonry walls or plastered and painted masonry surfaces. The proposed method can be particularly useful for heritage structures, and especially for acute problems like foundation settlement. Another advantage of the method is that it has been designed to be used by non-technical people, so that citizen involvement is also possible in collecting data from the field.

Energy dissipative steel cushions (EDSCs) are simple units that can be used to join structural members. They can absorb a substantial amount of seismic energy due to their geometric shapes and the ductile behavior of mild steel. Large deformation capability and stable hysteretic behavior were obtained in monotonic and cyclic tests of EDSCs in the framework of the SAFECLADDING project. Discrete numerical modeling strategies were applied to reproduce the experimental results. The first and second models comprise two-dimensional shell elements and one-dimensional flexural frame elements, respectively. The uncertain points in the preparation of the models included the mesh density, representation of the material properties, and interaction between contacting surfaces. A zero-length nonlinear link element was used in the third attempt in the numerical modeling. Parameters are recommended for the Ramberg-Osgood and bilinear models. The obtained results indicate that all of the numerical models can reproduce the response, and the stiffness, strength, and unloading and reloading curves were fitted accurately. Commission of the European Communities; FP7 Project "SAFECLADDING: "Improved Fastening Systems of Cladding Wall Panels of Precast Buildings in Seismic Zones", Research for SME Associations [314122] This research was conducted under the framework of the FP7 Project "SAFECLADDING: "Improved Fastening Systems of Cladding Wall Panels of Precast Buildings in Seismic Zones", Research for SME Associations, Grant Agreement Number 314122, which was coordinated by Dr. Alessio Rinoldi from BIBM, Belgium. The financial support provided by the Commission of the European Communities through this Project is greatly appreciated. The experimental study was conducted at the Structural and Earthquake Engineering Laboratory of Istanbul Technical University (STEELab). The support from laboratory staff and graduate students is gratefully acknowledged. Publisher's Version

Masonry structures comprise a significant portion of the historical building stock all over the world. Previous studies have clearly pointed out that unreinforced masonry buildings are vulnerable against extreme loading conditions, such as seismic actions. Therefore, strengthening is inevitable in most cases for historical masonry to withstand severe loads. In this paper, the efficiency of fabric reinforced cementitious matrix is investigated experimentally by using diagonal tension tests. Fourteen wallets with a nominal size of 750x750x235 mm were produced with using solid clay bricks and a low-strength mortar. The bricks were collected from the structural walls of an early-20th century building under restoration. The low-strength mortar represents the historical mortar commonly used in similar historical brick masonry buildings located in Istanbul, Turkey. By testing the specimens under monotonic diagonal compression loads, the effects of different types of plasters on the wallet surface, varying types of fibers used in textile reinforcement and anchors used for the connection between FRCM and substrate are investigated. Although the wallet samples have inherent shortcomings in representing overall component response accurately, still the qualitative findings are enlightening the effectiveness of the FRCM system by increasing shear strength, stiffness (shear modulus) and dissipated energy of the masonry wallets. The strengthened specimens were failed due to shear sliding along a bed joint and/or by a stair-shaped separation while the refence specimens were failed due to the splitting of the specimen into two parts in the stair-stepped shape and a slipping through a bed joint.

Masonry structures represent the highest proportion of building stock worldwide. Currently, the structural condition of such structures is predominantly manually inspected which is a laborious, costly and subjective process. With developments in computer vision, there is an opportunity to use digital images to automate the visual inspection process. The aim of this study is to examine deep learning techniques for crack detection on images from masonry walls. A dataset with photos from masonry structures is produced containing complex backgrounds and various crack types and sizes. Different deep learning networks are considered and by leveraging the effect of transfer learning crack detection on masonry surfaces is performed on patch level with 95.3% accuracy and on pixel level with 79.6% F1 score. This is the first implementation of deep learning for pixel-level crack segmentation on masonry surfaces. Codes, data and networks relevant to the herein study are available in: github.com/dimitrisdais/crack_detection_CNN_masonry .

During the 2015 Gorkha earthquake of 7.8 Mw that hit Kathmandu Valley, Nepal, numerous Nepalese Pagodas suffered extensive damage while others collapsed. Risk reduction strategies implemented in the region focused on disassembling historical structures and rebuilding them with modern material without in depth analysis of why they suffer damage and collapse. The aim of this paper is to evaluate the effectiveness of low-cost, low-intervention, reversible repair and strengthening options for the Nepalese Pagodas. As a case study, the Jaisedewal Temple, typical example of the Nepalese architectural style, was investigated. A nonlinear three-dimensional finite element model of the Jaisedewal Temple was developed and the seismic performance of the temple was assessed by undertaking linear, nonlinear static and nonlinear dynamic analyses. Also, different structural intervention options, suggested by local engineers and architects working in the restoration of temples in Nepal, were examined for their efficacy to withstand strong earthquake vibrations. Additionally, the seismic response of the exposed foundation that the Nepalese Pagodas are sitting on was investigated. From the results analysis, it was found that pushover analysis failed to capture the type of failure which highlights the necessity to perform time-history analysis to accurately evaluate the seismic response of the investigated temple. Also, stiffening the connections along the temple was found to enhance the seismic behaviour of the temple, while strengthening the plinth base was concluded to be insignificant. Outputs from this research could contribute towards the strategic planning and conservation of multi-tiered temples across Nepal and reduce their risk to future earthquake damage without seriously affecting their beautiful architectural heritage.

The seismic assessment of unreinforced masonry (URM) buildings with cavity walls is a relevant issue in many countries, such as in Central and Northern Europe, Australia, New Zealand, China and several other countries. A cavity wall consists of two separate parallel masonry walls (called leaves) connected by metal ties: an inner loadbearing wall and an outer veneer having mostly aesthetic and insulating functions. Cavity walls are particularly vulnerable structural elements. If the two leaves of the cavity wall are not properly connected, their out-of-plane strength may be significantly smaller than that of an equivalent solid wall with the same thickness. The research presented in this paper focuses on a mechanical model developed to predict the failure mode and the strength capacity of metal tie connections in masonry cavity walls. The model considers six possible failures, namely tie failure, cone break-out failure, pull-out failure, buckling failure, piercing failure and punching failure. Tie failure is a predictable quantity when the possible failure modes can be captured. The mechanical model for the ties has been validated against the outcomes of an experimental campaign conducted earlier by the authors. The mechanical model is able to capture the mean peak force and the failure mode obtained from the tests. The mechanical model can be easily adopted by practising engineers who aim to model the wall ties accurately in order to assess the strength and behaviour of the structures against earthquakes. Furthermore, the proposed mechanical model is used to extrapolate the experimental results to untested configurations, by performing parametric analyses on key parameters including a higher strength mortar of the calcium silicate brick masonry, a different cavity depth, a different tie embedment depth, and solid versus perforated clay bricks.

In recent years, the number of human-induced earthquakes in Groningen, a large gas field in the north of the Netherlands, has increased. The majority of the buildings are built by using unreinforced masonry (URM), most of which consists of cavity (i.e. two-leaf) walls, and were not designed to withstand earthquakes. Efforts to define, test and standardize the metal ties, which do play an important role, are valuable also from the wider construction industry point of view. The presented study exhibits findings on the behavior of the metal tie connections between the masonry leaves often used in Dutch construction practice, but also elsewhere around the world. An experimental campaign has been carried out at Delft University of Technology to provide a complete characterization of the axial behavior of traditional connections in cavity walls. A large number of variations was considered in this research: two embedment lengths, four pre-compression levels, two different tie geometries, and five different testing protocols, including monotonic and cyclic loading. The experimental results showed that the capacity of the connection was strongly influenced by the embedment length and the geometry of the tie, whereas the applied pre-compression and the loading rate did not have a significant influence.

Background The FI-35 is a valid multidimensional Chinese frailty assessment instrument. Like other scales, functional measures rely on the information the total score provides. Our research aimed to analyze the contribution of each item. Methods Descriptive statistics were used to summarize the sample characteristics. The expected item score (EIS) was used to determine how the items contribute to the generic measure of frailty. Results This study showed that most of the EIS curves increased across the entire range of frailty levels, and most of the items discriminate relatively well over the entire frailty range. Items differentially contributed to the total frailty score and differentially discriminated between frailty levels. Conclusions Although nearly all items monotonically increased with frailty levels, there were large differences between items in their ability to differentiate between persons being either weakly, moderately or highly frail.

The assessment of the out-of-plane response of unreinforced masonry (URM) buildings with cavity walls has been a popular topic in regions such as Central and Northern Europe, Australia, New Zealand, China and several other countries. Cavity walls are particularly vulnerable as the out-of-plane capacity of each individual leaf is significantly smaller than the one of a solid wall. In the Netherlands, cavity walls are characterized by an inner load-bearing leaf of calcium silicate bricks, and by an outer veneer of clay bricks that has only aesthetic and insulation functions. The two leaves are typically connected by means of metallic ties. This paper utilizes the results of an experimental campaign conducted by the authors to calibrate a hysteretic model that represents the axial cyclic response of cavity wall tie connections. The proposed numerical model uses zero-length elements implemented in OpenSees with the Pinching4 constitutive model to account for the compression-tension cyclic behaviour of the ties. The numerical model is able to capture important aspects of the tie response such as the strength degradation, the unloading stiffness degradation and the pinching behaviour. The numerical modelling approach in this paper can be easily adopted by practitioner engineers who aim to model the wall ties more accurately when assessing the structures against earthquakes.

The seismic assessment of unreinforced masonry (URM) buildings with cavity walls is of high relevance in regions such as in Central and Northern Europe, Australia, New Zealand and China because of the characteristics of the masonry building stock. A cavity wall consists of two separate parallel walls usually connected by metal ties. Cavity walls are particularly vulnerable to earthquakes, as the out-of-plane capacity of each individual leaf is significantly smaller than the one of an equivalent solid wall. This paper presents the results of an experimental campaign conducted by the authors on metal wall tie connections and proposes a mechanical model to predict the cyclic behaviour of these connections. The model has been calibrated by us- ing the experimental results in terms of observed failure modes and force-displacement responses. Results are also presented in statistical format.

KNAW – minisymposium ‘Aardbevingsbestendige woningen’ 24 maart 2020 Ondanks absentie van het symposium door de Corona crisis is dit boekje samengesteld voor digitale verzending en het drukken van een papieren versie.

This paper aims to quantify the evolution of damage in masonry walls under induced seismicity. A damage index equation, which is a function of the evolution of shear slippage and opening of the mortar joints, as well as of the drift ratio of masonry walls, was proposed herein. Initially, a dataset of experimental tests from in-plane quasi-static and cyclic tests on masonry walls was considered. The experimentally obtained crack patterns were investigated and their correlation with damage propagation was studied. Using a software based on the Distinct Element Method, a numerical model was developed and validated against full-scale experimental tests obtained from the literature. Wall panels representing common typologies of house façades of unreinforced masonry buildings in Northern Europe i.e. near the Groningen gas field in the Netherlands, were numerically investigated. The accumulated damage within the seismic response of the masonry walls was investigated by means of representative harmonic load excitations and an incremental dynamic analysis based on induced seismicity records from Groningen region. The ability of this index to capture different damage situations is demonstrated. The proposed methodology could also be applied to quantify damage and accumulation in masonry during strong earthquakes and aftershocks too. The work presented in this paper is supported by the – Seismic Monitoring, Design and Strengthening For thE GrOningen Region, Project number: RAAK.MKB09.021.

This paper aims to quantify the cumulative damage of unreinforced masonry (URM) subjected to induced seismicity. A numerical model based on discrete element method (DEM) has been develop and was able to represented masonry wall panels with and without openings; which are common typologies of domestic houses in the Groningen gas field in the Netherlands. Within DEM, masonry units were represented as a series of discrete blocks bonded together with zero-thickness interfaces, representing mortar, which can open and close according to the stresses applied on them. Initially, the numerical model has been validated against the experimental data reported in the literature. It was assumed that the bricks would exhibit linear stress-strain behaviour and that opening and slip along the mortar joints would be the predominant failure mechanism. Then, accumulated damage within the seismic response of the masonry walls investigated by means of harmonic load excitations representative of the acceleration time histories recorded during induced seismicity events that occurred in Groningen, the Netherlands.

Groningen gas field is the largest on-land gas resource in the world and is being exploited since 1963. There are damaging earthquakes, the largest of which was 3.6 magnitude. The recursive induced earthquakes are often blamed for triggering the structural damages in thousands of houses in the area. A damage claim procedure takes place after each significantly felt earthquake. The liability of the exploiting company is related to the damages and the engineering firms and experts are asked to correlate the claimed damages with a past earthquake. Structures in the region present high vulnerabilities to the lateral forces, soil properties are quite unfavourable for seismic resistance, and structural damages are present even without earthquakes. This situation creates a dispute area where one can claim that most structures in the region were already damaged because of the fact that the soil is soft, the ground water table oscillates, and structures are vulnerable to external conditions anyhow and deteriorate in time, which can be the main cause of such structural damages. This ambiguity of damage vs earthquake correlation is one of the main sources of the public unrest in the area up until today. This study presents the perspective of people in the region in terms of liveability and the social acceptance of earthquakes in their lives. An attempt has been made to translate these social effects and expectations into structural performance metrics for ordinary houses in the region. A new seismic design and assessment approach, called Comfort Level Earthquake (CLE) has been proposed.

Groningen gas field, which is being exploited for more than five decades, has been experiencing shallow and small magnitude earthquakes that cause limited structural damage to the building inventory in the region. These earthquakes are recorded in a relatively small area with multiple recording networks, which constitute a dense strong ground motion sensor grid, providing valuable insight into the characteristics of the motions produced by some 2500+ small faults at 3 km depth. The particularities of the Groningen soil, as well as the high seismic vulnerability of the structural inventory, render the Groningen earthquake problem complex, although the magnitudes experienced so far did not exceed 3.6ML. This paper is an attempt to compare the Groningen earthquake records to records from other induced seismicity and natural seismic events with similar characteristics in terms of magnitude, epicentral distance and depth, for identifying systematic differences in terms of component-to-component variability. In order to achieve that, a total of 1831 recording suites (i.e. couples of horizontal components) are used. 201 of these are Groningen records, 1112 are from other induced seismicity events to geothermal, waste water injection and hydraulic fracturing activities, while 517 are from natural earthquakes. The high polarity of the Groningen records, that is previously reported in the literature and represented as component-to-component variability in risk models, is the main focus of this paper. The component-to-component variability constitutes an important step when implementing ground motion models (GMMs) in risk assessment studies. In this study, in agreement with previous research, the component-to-component variances show that the Groningen induced seismicity events present stronger polarity than the other records used for comparison. The other induced seismicity recordings also show high component-to-component variances as compared to the natural events records, but the main difference is that their variances start decreasing in medium-to-long (i.e. above 0.6 s) periods while the variances steadily increase in the case of Groningen records. Furthermore, it is also observed that the component-to-component variances increase considerably when the rotated-to-max-PGA angle, explained in the paper, is used for defining the two horizontal components instead of using components as-recorded or rotated perpendicular to the station back azimuth. A modification to the component-to-component variance model of Groningen GMM v5 has also been proposed in this study for taking into account the orientation of the structural plan directions in respect to the ground motion component directions.

The majority of houses in the Groningen gas field region, the largest in Europe, consist of unreinforced masonry material. Because of their particular characteristics (cavity walls of different material, large openings, limited bearing walls in one direction, etc.) these houses are exceptionally vulnerable to shallow induced earthquakes, frequently occurring in the region during the last decade. Raised by the damage incurred in the Groningen buildings due to induced earthquakes, the question whether the small and sometimes invisible plastic deformations prior to a major earthquake affect the overall final response becomes of high importance as its answer is associated with legal liability and consequences due to the damage-claim procedures employed in the region. This paper presents, for the first time, evidence of cumulative damage from available experimental and numerical data reported in the literature. Furthermore, the available modelling tools are scrutinized in terms of their pros and cons in modelling cumulative damage in masonry. Results of full-scale shake-table tests, cyclic wall tests, complex 3D nonlinear time-history analyses, single degree of freedom (SDOF) analyses and finally wall element analyses under periodic dynamic loading have been used for better explaining the phenomenon. It was concluded that a user intervention is needed for most of the SDOF modelling tools if cumulative damage is to be modelled. Furthermore, the results of the cumulative damage in SDOF models are sensitive to the degradation parameters, which require calibration against experimental data. The overall results of numerical models, such as SDOF residual displacement or floor lateral displacements, may be misleading in understanding the damage accumulation. On the other hand, detailed discrete-element modelling is found to be computationally expensive but more consistent in terms of providing insights in real damage accumulation.

Fraeylemaborg is a noble house in an earthquake-stricken area of the Netherlands due to the induced seismicity events in the region. The structure is located in the middle of the town of Slochteren which gave its name to the largest gas field in the world upon its discovery in 1959. The gas extraction has caused small-magnitude shallow earthquakes during the last decade, damaging not only the residential inventory but also the historical structures in the area. The main building of Fraeylemaborg sits on an artificial island surrounded by water channels, rendering the problem of earthquake response even more complicated. A small part of the main structure on the island was built in the 14th century, while the construction of additional parts and morphological alterations had taken place until the 18th century. The structure has been subjected to several small magnitude earthquakes causing damages on the load bearing system. An extensive renovation and repair of damages took place in recent years, however the latest seismic events imposed again damage to the structure. This paper presents a project of monitoring, assessment and diagnosis of problems for the Fraeylemaborg, the most important “borg” of the region, underlining the particularities of the induced seismicity problem. The FE model has been calibrated by using ambient vibration tests. Combination of earthquake and soil settlement loads have been applied on the calibrated model. The paper develops scenarios that help in explaining the reasons behind the damages on this structure during the recent shallow and low-magnitude induced seismicity earthquakes.

Collapses of school or dormitory buildings experienced in recent earthquakes raise the issue of safety as a major challenge for decision makers. A school building is ‘just another structure’ technically speaking, however, the consequences of a collapse in an earthquake could lead to social reactions in the complex aftermath of a seismic tremor more than any other type of structure may possibly cause. In this paper a school building that collapsed during 2011 Tabanli, Van Earthquake in eastern Turkey, is analysed in order to identify the possible reasons that led to collapse. Apart from the inherent deficiencies of RC buildings built in Turkey in the 80's and 90's, its structural design exhibits a strikingly high asymmetry. In the analyses conducted, much attention has been given to the direction of the earthquake load and its coincidence with the bi-axial structural response parameters. The failure of the structure to comply with the 1975 Code, in vigor at the time of construction, has also been evaluated with respect to the structure’s collapse. Among the parameters that controlled the collapse, the high plan asymmetry and the coincidence of the vulnerable directions with the dominant shaking direction were critical, as well as the underestimation of the seismic hazard and the lateral design force level, specified by the then Turkish Earthquake Code.

The seismic performance of a two-story 2D frame and a five-story 3D frame–shear-wall structure founded on spread (isolated) footings is investigated. In addition to footings conventionally designed in accordance with “capacity-design” principles, substantially under-designed footings are also used. Such unconventional (“rocking”) footings may undergo severe cyclic uplifting while inducing large plastic deformations in the supporting soil during seismic shaking. It is shown that thanks to precisely such behaviour they help the structure survive with little damage, while experiencing controllable foundation deformations in the event of a really catastrophic seismic excitation. Potential exceptions are also mentioned along with methods of improvement.

Mild steel is relatively low-cost and easily accessible material to fabricate some structural members. It would be a significant advantage if seismic energy dissipaters that are used in structures constructed in the earthquake prone areas, could also be produced on site. In this paper, a promising seismic energy dissipater made of mild steel, so-called steel cushion (SC) is presented. It is provided experimental and analytical responses of SCs subjected to bi-axial loadings. SC rolls under the lateral loading that allows relocation of the plasticized cross-section. Henceforth, SC dissipates considerable amount of seismic energy. A series of tests were performed to achieve experimentally the behavior of SC subjected to longitudinal and transversal loading. Finite Element Models (FEMs) were also generated to reproduce the experimental backbone curves and to predict the bi-directional response properties for discrete transversal forces and plate thicknesses. Closed-form equations were derived to determine yield and ultimate forces and the corresponding displacements as well as location of the plasticized sections. The behavior of SC could either be projected by the FEMs with the exhibited parameters or by means of the proposed closed-form equations and the normalized design chart. The research presented herein was conducted in the framework of the FP7 project "SAFECLADDING: "Improved Fastening Systems of Cladding Wall Panels of Precast Buildings in Seismic Zones'' Research for SME Associations, Grant Agreement Number 314122, which was coordinated by Dr. Alessio Rinoldi from BIBM, Belgium. The financial support provided by the Commission of the European Communities through this project is greatly appreciated. The experimental study was conducted at the Structural and Earthquake Engineering Laboratory of Istanbul Technical University (STEELab). The supports of Laboratory staff and graduate students are gratefully acknowledged Publisher's Version

This paper investigates the limits and efficacies of the Fiber Reinforced Polymer (FRP) material for strengthening mid-rise RC buildings against seismic actions. Turkey, the region of the highest seismic risk in Europe, is chosen as the case-study country, the building stock of which consists in its vast majority of mid-rise RC residential and/or commercial buildings. Strengthening with traditional methods is usually applied in most projects, as ordinary construction materials and no specialized workmanship are required. However, in cases of tight time constraints, architectural limitations, durability issues or higher demand for ductile performance, FRP material is often opted for since the most recent Turkish Earthquake Code allows engineers to employ this advanced-technology product to overcome issues of inadequate ductility or shear capacity of existing RC buildings. The paper compares strengthening of a characteristically typical mid-rise Turkish RC building by two methods, i.e., traditional column jacketing and FRP strengthening, evaluating their effectiveness with respect to the requirements of the Turkish Earthquake Code. The effect of FRP confinement is explicitly taken into account in the numerical model, unlike the common procedure followed according to which the demand on un-strengthened members is established and then mere section analyses are employed to meet the additional demands.

The lack of in-depth understanding of the seismic behavior and ductility of precast concrete structures makes it difficult to reach to ductility demand which could be exhibited during an earthquake. The limitations are mainly related to the beam-to-column connections as the main load transfer paths. Two distinct exterior beam–column connections made of normal-strength concrete are investigated experimentally. Both dry and wet type installment techniques are used in the industrial type joints while the residential type joints are wet connections. The specimens are subjected cyclic displacement reversals in order to obtain information on strength, stiffness and ductility characteristics of the connection details. The preliminary design of the joints has been updated during the tests based on the damages observed, thus a set of improved specimens have also been built and tested, and a relatively better performance is obtained expectedly. The industrial and residential types of connections showed stable load–displacement cycles with high energy dissipation up to structural drift of 2%, though a significant level of pinching and deterioration of the critical section have occurred at around 3% drift level. The tested specimens have been numerically modeled to calibrate the analytical tools, and a satisfactory approximation has been obtained between experimental and numerical results.

Coupling beams between shear walls are one of the key elements for energy dissipation in tall buildings. A representative mathematical model of coupling beam should represent flexure, shear and interface slip/extension mechanisms simultaneously. This goal can be achieved by using either detailed finite element models or by using macro models. This paper presents a review of various macro model alternatives for diagonally reinforced coupling beams in the literature. Three distinct methods have been reviewed in terms of their modeling techniques, the cyclic response overlap and the amount of cumulative plastic energy dissipated based on the results of previously performed tests. Through an analytical study, adequately accurate results can be captured by using macro models, although they are simpler in practice compared to sophisticated micro models. This study shows that, by modifying ultimate shear capacities where concrete material between diagonal bundles is adequately confined, it is possible to capture a more realistic result and a better approximation to the actual responses. It is also concluded that a simpler numerical model for diagonally reinforced coupling beams can be achieved by introducing linear part of slip/extension behavior into elastic part of the beam. It is observed, as a result of this study, that the ratio of effective stiffness to that of the gross cross-sectional one ranges from 0.04 to 0.14 in diagonally reinforced coupling beams depending on the aspect ratio and the beam strength parameters.

Existing unreinforced masonry buildings in seismically active regions are in urgent need of consolidation and preservation against seismic action to prevent damage and loss of financial resources. In this research, an experimental study of externally confined brick masonry piers, which are frequently preferred as load-bearing elements in historical buildings, was conducted. The confinement system included a combination of open-grid basalt textile and mortar. Eighteen masonry pier specimens were produced using solid bricks collected from a historical building constructed in approximately the 1930s and a local mortar with substandard mechanical characteristics to simulate mortar properties in existing heritage buildings. All the square/rectangular pier specimens were tested under concentric compressive loads. In general, confinement of the tested textile-reinforced mortar (TRM) improved the energy dissipation of the masonry piers significantly. A comparison was made between the experimental results and theoretical predictions using the available analytical models. The compressive strengths predicted by the models are satisfactory.

Precast concrete structures are preferred for facilities with large open areas due to easiness in construction. Such structures are typically composed of individual columns and long-span beams, and are quite flexible and of limited redundancy. In this paper, nonlinear dynamic analyses of a typical such structure are conducted using as excitation 54 ground motions recorded on top of a variety of soils (hard, soft, and liquefied soil sites). The results show that liquefaction-affected level-ground motions systematically impose a greater threat to precast-concrete structures in terms of seismic demand, even when low values of elastic spectral acceleration prevail, as opposed to soft-soil records and even more to hard-soil ones. Thus, elastic spectral acceleration appears to be an insufficient engineering demand parameter for design. Soil effects, the “signature” of which is born on ground motions, are first uncovered using wavelet analysis to detect the evolution of the energy and frequency content of the ground motion in the time domain. From this, the changes in effective (“dominant”) excitation period are noted, persuasively attributed to the nature of the soil, and finally correlated with the observed structural behavior.

Itch (pruritus) is a common multidimensional complaint after burn that can persist for months to years. A questionnaire able to investigate itch and its consequences is imperative for clinical and research purposes. The current study investigated the factor structure, internal consistency and construct validity of the Burns Itch Questionnaire (BIQ), a questionnaire particularly focusing on itch in the burns population. The BIQ was completed by 195 respondents at 3 months after burn. An exploratory factor analysis (EFA) was performed to investigate the factor structure. EFA showed the BIQ comprised three latent factors: itch severity, sleep interference and daily life interference. This was re-evaluated in a confirmatory factor analysis that yielded good fit indices after removing two items. The three subscales showed to have high internal consistency (.89) and were able to distinguish between patients with severe and less severe complaints. In conclusion, the BIQ showed to be useful in persons suffering from itch following burns.

The effect of infill panels on the response of RC frames subjected to seismic action is widely recognised and has been subject of numerous experimental investigations, while several attempts to model it analytically have been reported. In this paper, the implementation, within a fibre-based Finite Elements program, of an advanced double-strut nonlinear cyclic model for masonry panels is described. The accuracy of the model is first assessed through comparison with experimental results obtained from pseudo-dynamic tests of large or full-scale frame models. This is followed by a sensitivity study whereby the relative importance of each parameter necessary to calibrate the model is evaluated, so that guidance on the general employment of the latter can be given. Furthermore, a representative range of values for the geometrical and material properties of the infill panels has been also defined. 1.

Exposure data available to developers of earthquake loss models are often very crudely aggregated spatially, and in such cases very considerable effort can be required to refine the geographical resolution of the building stock inventory. The influence of the geographical resolution of the exposure data for the Sea of Marmara region in Turkey is explored using several different levels of spatial aggregation to estimate the losses due to a single earthquake scenario. The results show that the total damage over an urban area, expressed as a mean damage ratio (MDR), is rather insensitive to the spatial resolution of the exposure data if a sufficiently large number of ground-motion simulations are used. However, the variability of the MDR estimates does reduce as the spatial resolution becomes higher, reducing the number of simulations required, although there appears to be a law of diminishing returns in going to very high exposure data resolution. This is largely due to the inherent and irreducible spatial variability of ground motion, which suggests that if only mean MDR estimates are needed, the effort required to refine the spatial definition of exposure data is not justified.

Assessment of the seismic vulnerability of the building stock in the earthquake-prone Marmara region of Turkey is of growing importance since such information is needed for reliable estimation of the losses that possible future earthquakes are likely to induce. The outcome of such loss assessment exercises can be used in planning of urban/regional-scale earthquake protection strategies; this is a priority in Turkey, particularly following the destructive earthquakes of 1999. Considering the size of the building inventory, Istanbul and its surrounding area is a case for which it is not easy to determine the structural properties and characteristics of the building stock. In this paper, geometrical, functional and material properties of the building stock in the northern Marmara Region, particularly around Istanbul, have been investigated and evaluated for use in loss estimation models and other types of statistic- or probability-based studies. In order to do that, the existing reinforced concrete (RC) stock has been classified as 'compliant' or 'non-compliant' buildings, dual (frame-wall) or frame structures and emergent or embedded-beam systems. In addition to the statistical parameters such as mean values, standard deviations, etc., probability density functions and their goodness-of-fit have also been investigated for all types of parameters. Functionalities such as purpose of use and floor area properties have been defined. Concrete properties of existing and recently constructed buildings and also characteristics of 220 and 420 MPa types of steel have been documented. Finally, the financial effects of retrofitting operations and damage repair have been investigated. © 2007 Elsevier Ltd. All rights reserved.

DBELA is a Displacement-Based Earthquake Loss Assessment methodology for urban areas which relates the displacement capacity of the building stock to the displacement demand from earthquake scenarios. The building stock is modeled as a random population of building classes with varying geometrical and material properties. The period of vibration of each building in the random population is calculated using a simplified equation based on the height of the building and building type, whilst the displacement capacity at different limit states is predicted using simple equations which are a function of the randomly simulated geometrical and material properties. The displacement capacity of each building is then compared to the displacement demand obtained, from an over-damped displacement spectrum, using its period of vibration; the proportion of buildings which exceed each damage state can thus be estimated. DBELA has been calibrated to the Turkish building stock following the collection of a large database of structural characteristics of buildings from the northern Marmara region. The probabilistic distributions for each of the structural characteristics (e.g. story height, steel properties etc.) have been defined using the aforementioned database. The methodology has then been applied to predict preliminary damage distributions and social losses for the Istanbul Metropolitan Municipality for a Mw 7.5 scenario earthquake.

A damage estimation exercise has been carried out using the building stock inventory and population database of the Istanbul Metropolitan Municipality and selected European earthquake loss estimation packages: KOERILOSS, SELENA, ESCENARIS, SIGE, and DBELA. The input ground-motions, common to all models, correspond to a “credible worst case scenario” involving the rupture of the four segments of the Main Marmara Fault closest to Istanbul in a Mw 7.5 earthquake. The aim of the exercise is to assess the applicability of the selected software packages to earthquake loss estimation in the context of rapid post-earthquake response in European urban centers. The results in terms of predicted building damage and social losses are critically compared amongst each other, as well as with the results of previous scenario-based earthquake loss assessments carried out for the study area. The key methodological aspects and data needs for European rapid post-earthquake loss estimation are thus identified.

Based on the soil data established previously by a team of researchers at the Technical University of Istanbul, a wave amplification study is conducted for the town of Avcılar, Istanbul, located at about 120 km west of the epicentre of the Kocaeli earthquake of August 17, 1999. It is determined, through the use of well known computer program SHAKE, that the three major predominant periods of the ground are, 1.60, 1.00 and 0.70 s. Thus, the reasons of extensive damage occurred to 5–8 storey high residential buildings in the region, may be attributed to both the long distance effects of the high period waves of the earthquake and soil amplification.

Deformation quantities such as strain, curvature and displacement are of paramount importance in seismic design within a performance-based procedure that aims to control the structural response at predefined levels of inelastic action. Given the importance of curvature expressions independent of strength for the design process, and for the particular case of T-shaped walls, the curvature trends at yield, serviceability and ultimate limit state are determined in graphical and analytical form. The comprehensive set of equations proposed in this work are strength independent and allow the reliable computation of limit-state curvatures, essential in a displacement-based design approach, and thus the realistic estimation of appropriate ductility factors in the design of T-shaped walls. Furthermore, results regarding the section properties of T-shaped walls, such as the elastic stiffness and the moment capacity for opposite directions of loading, offer additional information on T-shaped walls.

The Mw = 6.3 Christchurch earthquake was a surprising and unusual event which occurred in an unknown fault that had already been awakened by the September 2010 stronger earthquake, and it had a strong thrust component and a steeply dipping plane. This paper has attempted to identify quantifiable parameters that could provide better insight to seismologists and engineers who try to systematically investigate the reasons behind the structural and soil failures that occurred in the February shaking

Seismic risk assessment of two real RC multi-story buildings, located on similar soil profile in Kocaeli, is conducted in respect to code-based linear and nonlinear approaches, as well as to P25-v2 Method, a recently suggested method for risk evaluation and preliminary assessment of existing buildings against life-loss. Twenty-five different parameters and seven different collapse criteria are taken into consideration in the suggested P25-v2 Method, including soil and topographic conditions, earthquake demand, various structural irregularities, material and geometrical properties, and location of the buildings. After summarizing the different methodologies and describing the case study buildings, 3D linear-elastic and static nonlinear analyses are performed in parallel to the application of the P25 Method-v2. One of the two case study buildings totally collapsed during 1999 Kocaeli Earthquake, while the other survived with negligible damage, noting that both had legal construction and occupation permissions. SAP2000 and SeismoStruct software packages have been utilised for the analysis procedure to find out the damage states of the structural members at critical stories and to determine the performance levels of the case study buildings. The code-based performance levels and the final performance scores obtained by the preliminary assessment technique are compared in order to underline the existence of the correlation between the detailed procedure and the suggested preliminary assessment technique with the real damage state. Consequently, structural inadequacies, weak points of the buildings and failure reasons are also discussed in this paper.