Journal of Structural Engineering & Applied Mechanics
Hussien Alkasim Soalih
Several studies have been made on timber concrete composite shear connectors and most of these connectors are brittle at failure. Ductile shear connectors are not studied as extensively as ordinary shear connectors and the interest to study high ductility shear connectors increased in the past two decades. Recent literature references were chosen and reviewed on construction techniques of timber concrete composite shear connectors. A detailed summary of timber concrete composites, the mechanical properties of connectors, and types of connection systems are presented. Experimentally validated design guides available for timber concrete composite systems are presented and the potential for the development of new simplified connectors is discussed. Finally, recent applications of timber concrete composite connectors and possible areas of future research regarding the development of high ductility and energy dissipation capacity shear connectors are stated.
Sadık Can Girgin
İbrahim Serkan Mısır
Seismic performance evaluation of existing reinforced concrete buildings requires numerical approaches that reflect the damage modes that may arise from deficiencies in beam-column joints. In this study, the seismic performance of an existing reinforced concrete building with four stories was investigated by applying elastic and deformable beam-column joint models. The deformable beam-column joint model was verified using an exterior non-ductile beam-column joint test. The model included a rotational spring located at the joint with two connected nodes in a zero-length with rigid elements in the vicinity of frame elements. Moment- rotation relationships represent the joint behavior, and they were defined based on shear stresses and strains. After effective modeling of beam-column joints, it was aimed to obtain the cyclic behavior of the building model using non-linear time history analysis. For this purpose, scaled earthquake records were applied to the three-dimensional numerical model, and the results were compared in terms of inter-storey drift ratios, column and beam chord rotations, and base shear. It was determined that the exterior beam-column joints reached their strength and deformation capacity, while the beam and columns remained below their section deformation limits according to the Turkish Earthquake Code.
On November 21, 2021, a 5.1 magnitude earthquake occurred with its epicenter in Erzurum-Köprüköy. In the eastern part of our country, most of the building stock in rural areas and certain parts of city center is made up of masonry structures. Most of the masonry structures consist of rubble stone walls with very low tensile strength. These load bearing elements, which are exposed to out-of-plane and in-plane displacements due to earthquakes, can be easily damaged due to their low tensile strength and poor manufacturing. In this study, the damage mechanisms of the masonry structures in the villages of Alaca, Kayabaşı, Marifet, and Sarıtaş have been reported. As a result of field studies, damages are quite prevalent due to inadequate connections between load-bearing walls and roof. Additionally, the weak connection between the leaves of load-bearing walls and lack of connection in the junctions of the walls have contributed to the damages. he observed damages can be generally classified as the quality of workmanship/construction, inadequate material characteristics, weak load bearing walls, lack of proper connections, failure of unconfined or high gable walls, heavy earth roof. Many of the damaged structures have not adhered to regulatory recommendations and are buildings that did not receive engineering services.
Suleyman Istemihan Cosgun
Historical masonry structures with aesthetic aspects play an important role in cultural heritage. However, such structures are vulnerable to seismic effects. Therefore, periodic maintenance and structural evaluations are required for these structures. In this study, a historical masonry building called the Pertev Pasha Mansion, located in Trabzon, Turkey, was selected for the evaluation. The building was demolished in the last few years and has been planned to be rebuilt in its original form. In the study, the finite element model of the building was created based on reconstruction drawings. Modal analysis was performed to obtain the frequencies and mode shapes of the building. Finally, seismic analyses were conducted based on the February 6 Kahramanmaraş earthquakes for two different acceleration records that were collected from different stations, one near the epicenter (Pazarcık station) of the earthquake and the other near the building (Ortahisar station). From the results of the modal analysis, the frequency and mode shapes of the structure were obtained. The displacement and stress results were obtained from the seismic analysis and presented with contour diagrams. At the end of the study, a general evaluation considering the novel Turkish guidelines for historic structures was conducted. According to the results of the seismic analysis performed using the Pazarcık station data, the drift ratio values of the structure exceeded 0.7%, which corresponds to the Collapse Prevention (CP) performance level. However, according to the seismic analysis results obtained using Ortahisar station data, the maximum drift ratio of the structure was 0.001%, corresponding to the Limited Damage (LD) performance level. Consequently, if the building had been built close to the center of the earthquake, it was likely to collapse, but it was estimated that it would have received limited damage because its current location was far from the center of the earthquake.
Merve Küçükali Öztürk
Nanofibrous structures are engineered materials for high-end applications. The impact of electrospinning settings on the thermal and acoustic properties of polyurethane (PU) nanofibrous structures is examined in this research. The excellent sound-absorbing properties of PU make it a versatile material that may be used in a variety of acoustic applications. The study focuses on how PU nanofiber morphology, such as fiber diameter and volume fraction, is affected by varying ambient conditions. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are used to examine the stability and thermal behavior of PU nanofibers. The findings show that raising the fiber volume fraction improves thermal stability and changes the way PU nanofibers behave thermally. PU nanofiber webs provide efficient sound absorption in low and intermediate frequency ranges according to the study's analysis of the sound absorption coefficients. According to the results, PU nanofiber webs may offer novel approaches to noise control, especially in situations where acoustic panel insulation is needed with no weight penalty.
Berivan Yılmazer Polat
Geopolymer concrete (GC) has been found to have better results than Portland cement concrete (PCC), including lower carbon dioxide emissions, higher compressive strength, and greater durability. The study aims to determine the effects of basalt fiber on GC due to the impact caused by the sudden loading effect. Samples were prepared with different mixing ratios for the experimental process, with PCC used as the control sample. Basalt fibers were added to the samples in three different ratios based on optimal mixing ratios determined through physical and mechanical tests, such as UPV (Ultrasonic Pulse Velocity), compressive strength, and flexural strength. Subsequently, fibrous samples were analyzed using SEM (scanning electron microscopy) and EDS (energy dispersive spectroscopy). A drop-weight experiment was conducted on GC plates measuring 50×50×5 cm, which contained two different fiber ratios that yielded the best mechanical and physical properties. The results were analyzed using numerical modeling methods. No changes in content were made. The sample with the highest impact resistance was found to be the 2% basalt fiber-reinforced GC, with a displacement value 21.21% lower than PCC. The language used is clear, concise, and objective, with a formal register and precise word choice. The text follows a logical structure with causal connections between statements and adheres to conventional academic formatting and citation styles. The ANSYS modeling results indicated an 89.63% similarity with the experimental data regarding the displacement values. Additionally, the study demonstrated that the inclusion of basalt fiber additives enhances the impact resistance of geopolymer concrete. Furthermore, numerical modeling can predict the impact behavior of concrete to a significant extent, eliminating the need for experimental processes.