Yükleniyor…
Yükleniyor…
4
Arşivlenen Tez
3
DOI Atanmış
0
Enstitü
75%
DOI Oranı
ABSTRACT: The success of construction projects is highly dependent on meeting the aim of project and objectives within the specified time and budget. Management plays a big role in construction projects. Most important problems that management faces in the projects are methods of execution, management of workers, equipment, scheduling and money. Delay and cost overrun are two of the important defects in construction industry. These failures can lead to various types of negative affections like disputes between contractor and client, decrease quality of work and health and safety accidents. Therefore, there is a high necessity for further investigation on delay and cost overrun factors as well as quality and health & safety and suggesting right actions to minimize these kinds of defects. Keywords: Delay, Time overrun, Cost overrun, Investigation ………………………………………………………………………………………………………………………… ÖZ: İnşaat sektöründe projelerin başarısı, projenin belirtilen süre ve bütce dahilindeki hedeflerine ulaşmasına bağlıdır. Yönetim, inşaat projelerinde büyük bir rol oynar. Proje yönetiminde karşılaşılan en önemli faktörler yürütme işleri, işçilerin yönetimi, ekipman, planlama ve paradır. Gecikme ve maliyet taşması, inşaat sektöründe yer alan önemli kusurlarından ikisidir. Bu başarısızlıklar, çeşitli tiplerde olumsuz etkilere yol açabilir. Örneğin, müteahhit ve müşteri arasındaki anlaşmazlıklar, iş kalitesinin azalması ve iş sağlığı ve güvenliği kazalarıdır. Bu nedenle, gecikme, maliyet taşması, ve ayrıca kalite, iş sağlığı ve güvenliği ile ilgili daha fazla araştırmaya gerek vardır.İnşaat Anahtar Kelimeler: Gecikme, Zaman taşması, Maliyet taşması, Araştırma.
Deterioration due to corrosion becomes a more serious problem when the exact time of expected earthquakes is unknown. Therefore, the prediction of performance levels of corroded reinforced concrete (RC) structures is important to prevent serious premature damage. Many models have been developed regarding the effects of corrosion as a function of time. It is possible to evaluate and identify the performance level of RC structures as immediate occupancy (IO), life safety (LS), collapse prevention (CP), and collapse (C). The first part of this study contributes to an understanding of time dependent effects of corrosion on seismic performance levels of corroded RC buildings that will be a guideline for the further studies for strengthening and assessing of RC buildings. The developed model in the first part of this thesis provide to predict the time dependent seismic performance levels of RC buildings by considering three major effects of corrosion (e.g., deformation due to bond-slip relationships, loss of cross sectional area of reinforcement bars and reduction in concrete compressive strength). In second part of this thesis, the effect of corrosion on the bond strength between reinforcement bars and concrete was studied in a series of experiments. An accelerated corrosion method was used to corrode the reinforcement bars embedded in concrete specimens. Pullout tests were performed to develop an empirical model for the ultimate bond strength by evaluating bond strengths in two different concrete mixes, three concrete cover depths and different mass losses of reinforcement bars after corrosion. Bond-slip relationships for the different corrosion levels were compared for different concrete classes and concrete cover depths.
Since the earthquakes in Northridge and Kobe in 1994 and 1995 respectively, many investigations have been carried out towards improving the strength and ductility of steel beam to column pre and post-Northridge connections. In order to achieve these objectives recent researches are mainly focused on three principles; reducing the beam section to improve the beam ductility, adding different kinds of slit damper to beam and column flanges to absorb and dissipate the input earthquake energy in the connection and strengthening the connection area using additional elements such as rib plates, cover plates and flange plates to keep the plastic hinges away from the column face. This research presents a reduced beam section approach via the introduction of multi longitudinal voids (MLV) in the beam web for various beam depths varying from 450mm to 912mm. ANSYS finite element program was used to simulate the three different sizes of SAC (Structural Engineering Association of California) sections, SAC3, SAC5 and SAC7. Then the modification was applied to these post-Northridge SAC sections. Results showed an improvement in the connection ductility since the input energy was dissipated uniformly along the beam length and the total rotation of the connection was over four percent radian. Keywords: Multi-Longitudinal Voids; Strength; Ductility; post-Northridge connection.
Many destructive earthquakes occurred in Cyprus. However, the potential seismic risk of the buildings in Cyprus is not known well since vulnerability is unknown. Especially in the Northern part of the Island building inventory has variation regarding seismic performance. On the other hand, in Northern Cyprus there are more than 150 school buildings with different ages. Most of these buildings have been constructed before the use of modern seismic codes. In other words, only gravity loads have been considered in the design of these school buildings. It is, therefore of paramount importance for us to identify seismic risk of buildings and especially school buildings. Other important point is the corrosion of steel reinforcement in concrete, based on structure age and environmental causes, would easily decrease the service life of buildings. This could cause a disaster in case of an earthquake. The natural disasters could cause loss of human lives and increase the cost of repair of damaged buildings. In this thesis, Gazimağusa Namık Kemal Lisesi (GMNKL) was evaluated as a reference school building and possible remedial measures for the building were discussed. GMNKL building is reinforced concrete and it has been constructed in 1956. This research was performed in three parts. In the first part, visual inspection of GMNKL was performed and deteriorations observed and other factors influencing earthquake resistance were determined. In the second part, material strengths (concrete and steel) were determined by using destructive and non-destructive tests. Also, reinforcement details were determined. Following the data collection, linear elastic and nonlinear static analysis were performed to identify possible weaknesses of buildings. Finally, in the third part of the research possible rehabilitation techniques were recommended. In order to collect information several tests were performed on concrete and reinforcement of the building. Among these tests one of the test was the determination of corrosion potential and the results were used in the analysis. Analysis was based on FEMA 356, ATC-40 and Turkish Earthquake Code (2007). After analysis results of the existing building, the most suitable strengthening methods were selected to increase performance level of existing building. The strengthening methods used were column jacketing and shear wall construction. Applied strengthening methods were compared to each other based on the economic analysis and the seismic performance. The shear wall method was selected to be the best strengthening method based on criterias stated above. It is expected that this study will be a reference for studying school buildings in other regions of Cyprus