Journal of Civil Engineering Beyond Limits (CEBEL)

Asim Osman Nada Abdalla Khogali

This paper, is a part of continuous research, aims to examine the suitability of cast-in-place Ferro cement composite slab as a roof/floor system. This continuous study is mainly based on experimentation. Ferro cement is a combination of cement/sand (1:2.5) mortar, having a compressive strength higher than 30 N/mm², and expanded metal with R6mm bars. Can be formed in any shape not more than 50 mm thickness. Two panels each consist of a 50 mm slab casted over corrugated zinc sheet of 1.0m width and 4.5 m length supported by two rectangle steel pipes, along the long side and spaced at 50 cm. The pipes were connected to the panels by self –drill screws and shear keys. Steel pipes were (120 mm x 50 mm x 1.8 mm) and (100 mm x 50 mm x1.8 mm) for each panel A and B respectively. As cast-in-place technique, the whole floor will be casted in a single day, whereas, precast panels require forms and handling effort. Panels were tested using 50 kg cement bags as a uniform distributed load. The experimental results show that panels have enough strength and can be used within the allowable service deflection limit, as a roof/floor system.

https://doi.org/10.36937/cebel.2020.001.001

Emre Alpaslan Zeki Karaca

Experimental investigations of large and complex structural systems can be carried out by reduced- scale models in terms of convenience, time-saving and economical. This can be applied to different fields of study such as vibration, impact and explosion problems in structural engineering and allows reliable analysis to understand the static and dynamic behavior of real structures called a prototype. This study aims that a 1/3 reduced-scale model is created in the laboratory environment considering similitude requirements by selecting a single span historical masonry arch bridge as a prototype structure. For this purpose, the Operational Modal Analysis (OMA) Technique is utilized for experimental study to determine modal parameters of the prototype and model bridges. Sensitive accelerometers were located on critical points on the structures and signals originated by accelerometers were collected to quantify the vibratory response of the model and prototype bridges. The Enhanced Frequency Domain Decomposition (EFDD) is employed to identify the natural frequencies, mode shapes, and damping ratios experimentally. The similarity of the dynamic behavior of the reduced-scale bridge model and prototype are investigated. The analysis of the similarity in the dynamic behavior of the prototype and model bridge consists of two steps. The first step involves comparing the natural frequencies corresponding to the translational, bending and torsional modes of the prototype and model bridges. This comparison was made in accordance with the similitude requirements. The second step includes the comparison of the corresponding mode shapes obtained from the prototype and the model bridge by utilizing the modal assurance criterion (MAC). As a result of the study, it is concluded that the dynamic behavior of the reduced-scale bridge model is similar to the dynamic behavior of the prototype bridge.

https://doi.org/10.36937/cebel.2020.001.002

Muzaffer Kerem Ertek Gökhan Demir Utku köktan

Constitutive modeling of soils is a crucial topic in geotechnics. Several constitutive models for geotechnical analyses can be found in material libraries of open-source or commercial geotechnical software packages, and these models can be based on various theories. Hypoplasticity as a relatively young theory is an alternative to elastoplasticity and consistently attracts new researchers. Contrary to elastoplasticity, hypoplasticity does not involve a priori defined yield surface, flow rule and plastic potential and arises from a simple tensorial function of the rate type. An exhaustive review of literature, however, points to the fact that for the calibration of these models, commercial symbolic mathematics software is mostly referred to and a calibration procedure based upon an open-source software which any individuals can easily make use of is totally missing. Therefore, an explicit procedure for calibration making use of NumPy, which is the main package for scientific computing with Python, following a concise summary for the theory of hypoplasticity is established. By doing so, it is expected to draw attention to take advantage of open-source packages that almost the majority of the scientific community utilize increasingly.

https://doi.org/10.36937/cebel.2020.001.003

Ahmet Şahin Zaimoğlu Neşe Işık Bünyamin Dönmez Temel Yetimoğlu

In this study, the effects of bentonite clay were investigated in the cleaning of the andesite stone samples used in the restoration of historical Çobandede Bridge and some historical buildings contaminated with sodium chloride salt. The stones of historical buildings are exposed to harmful salt effects for various reasons. Especially in regions where terrestrial climate dominates, the sodium chloride salt sprinkled on the icy roads for thawing may infiltrate over time into soil and then arrives at the historic bridges’ stones. In this way, because of capillarity of the stones and ionic osmos, the salt accumulates in the pores of the stones and the hygroscopic nature of NaCl damages the historic bridges’ stones on the road route. This physically damages the stone and reduces the life of historic bridges. Therefore, the removal of salt entering the structure of the stone is very important to increase the durability of the stones. In order to model this situation, a sum of bentonite clay paste prepared in liquid limit was implemented to artificially polluted andesite stone samples. The clay pastes applied to the stones were removed from the stones surfaces after a certain period of time and analyzed. X-ray Fluorescence Spectrometry (XRF) analyzes showed that bentonite clay gave positive results for sodium chloride removal from historical building stones exposed to NaCl salt.

https://doi.org/10.36937/cebel.2020.001.004

Mehmet Fatih Yılmaz Emre Alpaslan

Improvements in construction technologies have allowed steel structural elements to become more frequently used today in order to enable different architectural designs and to meet structural performance more effectively and efficiently. Structural steel has been used for more than a hundred years and has been tested under real earthquakes, which provide the basis of many earthquake-resistant steel construction standards. The major advantage of steel construction material is that it allows for large plastic deformations. Structural deformations vary depending on the deformation capacity of the structural components in addition to the configuration of the structural components. In this study, moment resisting frames (MRF), X braced frame (XBF), Inverse V braced frame (IVBF), K braced frame (KBF), and eccentric inverse V braced frames (EIVBF) were used to examine the effect of different steel braced systems on the plastic deformation capacity of steel structure with the help of nonlinear static pushover analysis. Bilinear material model was utilized to represent nonlinear steel material behavior and inelastic displacement-based frame element were used to represent column and beam element. The analyses' results demonstrated that the braced frame configuration had a significant effect on the lateral response of steel frame structures.

https://doi.org/10.36937/cebel.2020.001.005