The New Face of the Academia

Abstract

To perform accurate seismic analyses of corroded reinforced concrete (RC) buildings, it is necessary to predict the bond-slip relationships to modify the moment-curvature relationships. In this study, empirical models were developed to predict the bond strength of corroded RC columns. Twenty-five RC columns were tested under combined cyclic lateral displacement excursions for three concrete strength levels—specifically, 9, 27, and 37 MPa (1305, 3915, and 5365 psi, respectively)—at two axial load ratios of 0.20 and 0.40 and at four corrosion levels. An accelerated corrosion method was applied to corrode the reinforcing bars embedded in the RC columns. The actual corrosion levels were determined by breaking the concrete and extracting all the longitudinal and transverse reinforcing bars from the RC columns. Three empirical models were developed. The first model was used to predict the development length of the corroded reinforcing bars. The second and third models were used to predict the bond strength and slip in the reinforcing bars as a function of the corrosion levels. The results indicated that previous models that predict the bond strength of corroded RC members were limited because of the theoretically considered development length of the noncorroded reinforcing bars.

Abstract

This study considers 4 experimental raw data and a survery of dataset. Stress-strain relationships of A1 and A2, R1 python file for distribution radar chart of Taguchi as a different variable data, and moment-curvature relationship of A1 were obtained. For the current study the fifth data of S1 was taken from a survey dataset of 500 responses. It is explained how the experimentally obtained raw data, code file of python and survery dataset are uploaded to the RDL platform.

Abstract

Earthquakes of magnitude Mw = 7.7 and Mw = 7.6 hit the city of Kahramanmaraş (Turkey) on 6 February 2023. These earthquakes caused serious damage in 11 provinces in Turkey resulting in over 50,000 deaths and huge economic losses with the collapse of thousands of buildings. Two consecutive devastating earthquakes have severely damaged the reinforced concrete building stock located in Malatya. There are many reasons reinforced concrete structures suffer damage under the influence of seismic loads. These reasons can be listed as material and section properties that do not comply with earthquake codes, workmanship defects, ground parameters that are not considered and design errors, as seen in field investigations after earthquakes in Turkey in the past. In this research, a field study was conducted on reinforced concrete buildings damaged after the earthquakes in Malatya province. The causes of structural damages in reinforced concrete buildings between 6–26 years of age were assessed in terms of design and material defects. The structural damages were mainly caused due to insufficient stirrups in structural members, short column, strong beam–weak column, failures of infill walls, soft story type collapse, poor concrete quality, and reinforcement corrosion. In addition to the field investigation, the spectrum relationships created using raw acceleration data obtained from DEMP (Disaster and Emergency Management Presidency) stations in Malatya province were compared with the design response spectra.

Abstract

This study aimed to investigate the precast reinforced concrete beam-to-column joints behaviors through the replaceable damper under cyclic loading. The precast concrete specimens have been embedded with steel reinforcement and specially shaped connectors. After the application of the replaceable damper under cyclic loading, the energy dissipation shaped very well and increased the bearing capacity of precast specimens. The precast concrete beam–to–column joints were designed and analyzed to compare with the traditional reinforced concrete (RC) specimen. The analysis result of the loading based on the controlled displacement method showed that the precast specimen model with a damper has more hysterical behavior than the traditional RC frame. Also, the specimen (PS-1) is passed the 2.7% chord rotation, which showed higher performance, than the traditional RC specimen. The efficiency of the PS-1 specimen with a special connection has been elaborated with the finite element method (FEM) and simulated by ABAQUS software.

Abstract

Ductile behavior is one of the most important earthquake indicators that must be possessed by structures. Because of the limited tensile strength of concrete, alternative materials such as structural nanosynthetic fibers as three-dimensional reinforcement bars have gained increasing popularity over several decades. However, the contribution of fibers to the development length of reinforcement bars has not been investigated. Therefore, an experimental study was conducted to investigate the effects of polypropylene fibers on the development lengths of reinforcement bars. Thirty-three reinforced concrete (RC) slabs at three different volume fractions of fibers of 0.0, 1.0 and 1.5 % at different embedment lengths of reinforcement bars were investigated under four-point flexural strength tests. Load-displacement curves, energy absorption capacities, ductility ratios and bond-slip relationships were obtained for different embedment lengths of reinforcement bars with three different amounts of fibers in RC concrete slabs. The test results revealed that the predominant effects of fibers on structural behavior pertained to the energy absorption capacities at plastic deformation. It was found that resisting more strains by reinforcement bars with the help of added polypropylene fibers resulted in the regaining of ductile behavior due to the reduced embedment lengths of the reinforcement bars.

Abstract

Ce travail s' inscrit dans le cadre de l'analyse du discours et se conçoit selon une approche énonciative qui consiste à déterminer et à décrire les relations qui se tissent entre le discours du locuteur (le journaliste dans notre cas) et les différents éléments qui constituant le cadre énonciatif ainsi que les unités linguistiques appelées souvent les marques de l'énonciation. Deux stratégies discursives distinctes peuvent être adoptées par le journaliste énonciateur: soit un effacement énonciatif qui consiste à gommer toute trace de la présence du journaliste dans son discours; soit un engagement énonciatif dans lequel l'énonciateur prend en charge la responsabilité de ses dires. Notre étude constitue donc un croisement entre le domaine des sciences de l'information et celui de la linguistique. Elle est axée sur la question du positionnement énonciatif dans le discours journalistique. En effet, ce travail se propose d'étudier la subjectivité dans le dossier qui s' intitule: Boycott, les raisons d'un ras-le-bol, publié le 04 mai 2018 par l'hebdomadaire marocain TelQuel.

Abstract

This paper aims to develop a practical artificial neural network (ANN) model for predicting the punching shear strength (PSS) of two-way reinforced concrete slabs. In this regard, a total of 218 test results collected from the literature were used to develop the ANN models. Accordingly, the slab thickness, the width of the column section, the effective depth of the slab, the reinforcement ratio, the compressive strength of concrete, and the yield strength of reinforcement were considered as input variables. Meanwhile, the PSS was considered as the output variable. Several ANN models were developed, but the best model with the highest coefficient of determination (R2) and the smallest root mean square errors was retained. The performance of the best ANN model was compared with multiple linear regression and existing design code equations. The comparative results showed that the proposed ANN model was provided the most accurate prediction of PSS of two-way reinforced concrete slabs. The parametric study was carried out using the proposed ANN model to assess the effect of each input parameter on the PSS of two-way reinforced concrete slabs. Finally, a graphical user interface was developed to apply for practical design of PSS of two-way reinforced concrete slabs.

Abstract

This paper aims to develop a practical artificial neural network tool for predicting the axial compression capacity of circular concrete-filled steel tube columns with ultra-high-strength concrete. For this purpose, a nonlinear finite element analysis of circular concrete-filled steel tube columns with ultra-high-strength concrete was conducted and verified with experiments in the literature. Accordingly, a database of 768 finite element models was generated to use for developing the artificial neural network models. In this regard, the column length, the diameter of steel tube, the thickness of steel tube, yield and ultimate strength of steel tube, and compressive strength of concrete were considered as the input variables while the axial compression capacity was considered as an output variable. The performance of the proposed artificial neural network model was compared with the current structural design codes including AS/NZS 5100.6, Eurocode 4, AISC, and GB 50936. The comparative study indicated that the proposed artificial neural network model achieved a superior prediction compared to others. Ultimately, a graphical user interface tool was developed based on the proposed artificial neural network model to predict the axial compression capacity of circular concrete-filled steel tube columns with ultra-high-strength concrete for practical engineering design.

Abstract

Turkey is a country that is vulnerable to earthquakes and has experienced many major earthquakes that completely destroyed or caused significant damage to numerous historic structures. Today, using computer software, it is important to numerically model and analyze historic structures that need significant restoration and strengthening, to evaluate them from a perspective of seismic resistance, and to reinforce them without altering their originality. In this study, a finite element model of the historic Tigris Bridge on the Tigris River was created. First, the stresses and deformation caused by its own weight were determined. Subsequently, dynamic analyses were performed in the time domain using past earthquake ground motion records. Displacement and stress values obtained for each earthquake record in these time domain analysis were compared to each other to evaluate the seismic behavior of the bridge comparatively. The seismic performance of the bridge was determined on the basis of the “Guidelines on the Management of Earthquake Risks for Historic Structures” published by the Directorate General of Religious Foun-dations in Turkey.