Bilge Doran

Prediction of lateral confinement coefficient in reinforced concrete columns using neural network simulation

This paper presents an application of Neural Network (NN) simulation in civil engineering science. The confinement degree for confined concrete has been investigated by using a NN analysis as an alternative approach. To accurately predict the behavior of a confined concrete, it is important to understand the confinement degree and its individual components. For the purpose of investigating confinement effects, three empirical equations as a function of various parameters and an experimental work existing in the literature were considered in this study. However, these analytical models are time consuming to use. Therefore, there is still the need to develop simple but accurate method for determining the confinement coefficient. In this context, the NN algorithm has been established, in order to validate these empirical equations proposed for the confinement coefficient. The approach adapted in this study was shown to be capable of providing accurate estimates of lateral confinement coefficient, Ks by using the six design parameters. Finally, comparison with other empirical equations proposed for the lateral confinement coefficient illustrates the validity of the proposed algorithm.

Seismic Evaluation of Existing Wharf Structures Subjected to Earthquake Excitation: Case Study

The ability of aging shore structures to resist design seismic forces located in high-seismicity regions has been a subject of interest for many researchers. Seismic design codes have become more stringent and suggest the use of new design methods, such as performance-based design. According to the Turkish Code for Shore Structures (TCSS 2008), a pile-wharf structure is expected to withstand a D1 level of ground motion (corresponding to a return period of 72 years) with minor or no damage and a D2 level of ground motion (corresponding to a return period of 475 years) with short-term loss of serviceability. In this study, nonlinear static analyses of the seismic performance of two existing pile-wharf structures were performed (pushover analyses) according to TCSS (2008). The results are presented here.

Strain-Based Seismic Performance Evaluation of Prefabricated Structures

Precast concrete frame systems are widely preferred for the single storey industrial buildings in Turkey and Europe due to its rapid and economical construction practice. Field investigations after past major earthquakes revealed that the damage in such structures was primarily due to the improper detailing in beam–column connections and lack of required lateral stiffness. In this study, two different precast industrial buildings, damaged during the 1999 Marmara earthquake, were numerically investigated. The seismic performances of the buildings were evaluated by using Incremental Equivalent Seismic Load Method and strain-based damage definitions as recommended in Turkish Earthquake Code. The analytical results obtained from performance evaluations are compared with the findings from the field investigations.

Seismic Energy Demands of Inverted V-Braced Frames

It is known that structures act a nonlinear movement when strong ground motion cycle begins. Energy concept has been progressive tool to evaluate the structural system associated with performance-based design. Energy-based design can be expressed as the balance of energy input and the energy dissipation capacity of the structure. Researches that have been usually done for single degree of freedom system are needed for multi degree of freedom systems (MDOFs) in framework of the energy-based design methodology. In this paper, energy parameters in term of total energy input and hysteretic energy are evaluated and observed changes in height of the buildings for the energy concept. Structures are selected to demonstrate low and medium-rise steel inverted V-braced frames examined in linear and nonlinear dynamic time history analysis. The results are developed to obtain seismic energy demands.

Seismic Performance and Retrofit Evaluation of an Existing Pile-Wharf Structure

AbstractPile-wharf structures are one of the substantial facilities for marine transportation along the shorelines. Due to their logistical significance, keeping the pile-wharf structures operation...

In-Plane Shear Behavior of Traditional Masonry Walls

ABSTRACT The evaluation of the material properties of masonry built with traditional lime mortar remains largely unclear to what extent the complex mechanical behavior of its constituents and sampling difficulties. This article presents the experimental results of a research project carried out on the four unreinforced masonry (URM) walls with four different types of lime mortars used in the Roman and Byzantine periods under shear-compression. Besides, an elasto-plastic damage (EPD) approach is adapted calibrating the parameters of Oliver’s damage model and the modified von-Mises yield criterion for the masonry constituents. For the modeling purposes, a new fictitious joint material approach is introduced to describe the constitutive behavior of both mortar and mortar-brick interface. The proposed approach can be useful to describe the behavior of mortar and mortar-unit interface in existing masonry structures.

Ductility Enhancement in Reinforced Concrete Structure with Buckling Restrained Braced Frames

Adding braces to moment frames is considered to be quite an efficient technique for increasing the global stiffness and strength of the structure. It has not only been used in steel moment frames, but also in reinforced concrete (RC) moment frames in recent years. It certainly can increase the energy absorption capacity of structures and also decrease the demand imposed by seismic ground motions. Steel braces are anchored firmly to boundary beams and columns. They are modeled as truss elements and increase earthquake resistance of the building. Buckling restrained braced frames (BRBFs) in which members yield under both tension and compression without significant buckling have been used in recent years in order to ensure the desired seismic performance of special concentrically braced frames. BRBFs are similar to the special concentrically braced frames in that seismic accelerations are resisted by a building-frame members and diagonal braces whereas the design procedure is different. BRBs should be designed to permit ductile yielding both in compression and tension. In this paper, flat-slab RC building with two different configurations of buckling restraint braces (BRBs) is studied. The buildings have 4-storey with 5 bays in both X-and Y-directions and have been designed according to Turkish Specification of Reinforced Concrete Design (TS 500). In order to explore overall behavior up to failure and lateral load resisting capacities for these buildings, nonlinear static analyses have then been performed using SAP 2000-V14.1. Pushover analysis under constant gravity loads and monotonically increasing lateral forces during an earthquake until a target displacement is reached is generally carried out as an effective tool for performance based design. The major outcome of a pushover analysis is the capacity curve which shows the base shear vs. the roof displacement relationship and represents the overall performance of the building. The results of the analyses are presented in terms of capacity curve and energy dissipation.