Harun Türkoğlu

Istanbul Technical University · Department of Civil Engineering

Delays have commonly been a serious problem. This study aims to evaluate, criticize, and synthesize the literature on the causes of delays in construction. A total of 70 journal articles from 33 countries focussing on identifying the causes of delays were critically analysed. The main findings of this study are that the questionnaire survey is the...

Selecting the appropriate formwork system (FWS) is a critical aspect in the successful completion of reinforced concrete (RC) building construction projects. The selected FWS has a significant impact on the cost, time, and quality performances of the project. As there are many FWSs and formwork fabricators (FWFs) available, the selection of the FWS...

Reinforced concrete (RC) is used as the primary structural material in almost all construction projects worldwide, from infrastructure to building projects. Since formwork is an essential part of RC construction supply chain, it has a significant impact on the project performance. In the industrial formwork systems supply chain, the roles and respo...

The formwork system (FWS) in reinforced concrete (RC) construction is a critical component. The appropriate FWS is selected based on a number of conflicting and compromising criteria, and the selection of the FWS is carried out by construction professionals with different technical and/or administrative backgrounds. The perspectives and perceptions...

Formwork system (FWS) is one of the key components in reinforced concrete (RC) construction. Therefore, selection of the most appropriate FWS plays a critical role in the project success. Since the FWS selection is affected by several compromising and conflicting criteria, numerous studies have been carried out to identify the FWS selection criteri...

The success of a construction project is often evaluated by time, cost, and quality performances, which are interdependent. Shortening the project duration does not only increase the direct cost but also affects the project’s quality cost positively or negatively. In addition, the contract clauses in terms of penalty cost and early finish bonus hav...

Time and cost are two of the most important performance indicators of construction projects. Project crashing is one of the effective methods for solving time-cost trade-off problems. However, in some instances, consuming all of the crash durations of the activities may lead to inflexible schedules. This paper proposes a project crashing model that...

An unbalanced bid is a bid that contains manipulated unit bid prices that do not reflect the reasonable unit bid prices. Owners should be able to stop an unbalanced bid because it may increase the cost of construction. Therefore, the majority of the current literature on unbalanced bidding focused on how to detect unbalanced bids in order to reject...

In the construction industry, reinforced concrete (RC) has been adopted as the main structural material in almost all types of construction projects from infrastructure to building projects worldwide. In this context, RC is undoubtedly the most popular structural material in Turkey. Formwork is an integral part of RC structure supply chain, which c...

Project crashing, a.k.a. project compressing or time-cost trade-off, is an important aspect of managing construction projects. Project crashing can be defined as the time-cost optimization technique, which aims to compress the total project duration with the least incremental cost. In real life problems, the quality is affected when some activities...

Completing on time, within the estimated budget and at the desired quality are three main constraints of construction projects. However, construction projects become nowadays more complex than ever, so they are subjected to uncertainties and changes throughout the project life cycles. These uncertainties and changes may lead to severe delays in pro...

The management of resources has been claimed to be as important as scheduling methods. Inefficiency in managing resources may bring about severe delays and cost overruns caused by resource shortages in some cases and/or idle resources in others. Therefore, resources should be utilized efficiently to prevent project failures. Resource leveling is on...

Motivation is one of the key factors that stimulate individuals to improve their productivity. Therefore, motivation of construction workers has been debated with considerable interest by participants in the construction industry. However, motivating only construction workers, but ignoring the motivation of construction professionals, viz., archite...

Unbalanced bidding, also known as skewed bidding, is the process of increasing and/or decreasing the prices of various bid items without altering the total offered bid price. Bids can be unbalanced either mathematically (front-end loading) or materially (quantity error exploitation). Owners should be very careful when evaluating the tenders as awar...

Unbalanced bidding is a common practice used in both unit price and lump sum contracts. Contractors may unbalance their bids in different forms for various reasons. The studies in the literature either focus on developing optimization models that assist contractors in winning contracts and maximizing profits of their bids through unbalancing or dev...

Reinforced concrete (RC) structures have been predominant structural materials for over a century, and are still the most popular material all over the world. In this context, Turkey is not an exception and RC is one of themost commonly used structural materials. The construction of a RC structure consists of five main activities, which include: 1)...

Environmental issues are one of the motivators that advances construction means and methods. Therefore, perceived importance of the selection of Heating, Ventilating and Air Conditioning (HVAC) systems and suppliers become highlighted for the buildings trying to be certified as “green”. Air-Handling-Units (AHU) are one of the most fundamental compo...

Nowadays, the concept of green building is no longer an alternative but a necessity. The acceptance of a building as “green” depends on having a certificate. LEED is one of the widely used green building certification systems in Turkey. The main objective of this study is to find out whether there were statistically significant differences between...

Construction projects are subjected to a variety of risks eventually affecting the overall duration and green building projects are no exception. Use of risk assessment means in such projects is also critical to complete them within aimed schedule. In this study, risks that have potential schedule impacts in certified green building projects are id...

A structural system carries all loads acting on the building and transfers them effectively to the soil through the foundation. Since it is the essential component of a building, selecting the most appropriate structural system is one of the critical decisions in the structural design. The design team, which consists of engineers and architects, is...

Construction project scheduling requires additional parameters and estimation if the projects are equipment intensive. Since preventive maintenance, multiple movement operations, and sitting idle vehicles affect not only the activity or the total project duration, but also the budget of the project, heavy equipment scheduling deserves a special foc...

Green projects, especially housing projects, have become popular in recent years in the Turkish construction industry. Although the number of green projects is increasing, this type of projects involves several material-related risks. The contractors, who undertake green projects, should be aware of these risks and take precautions against them in...

Construction and demolition (C&D) waste is defined as the waste produced during new construction, renovation, and demolition of buildings and structures. C&D waste is becoming one of the most serious environmental problems. Indeed, recent studies reveal that C&D waste constitutes approximately 10–30% of the waste received at many landfill sites aro...

Construction and demolition (C&D) waste is defined as the waste produced during new construction, renovation, and demolition of buildings and structures. C&D waste is becoming one of the most serious environmental problems. Indeed, recent studies reveal that C&D waste constitutes approximately 10–30% of the waste received at many landfill sites aro...

Green projects, especially housing projects, have become popular in recent years in the Turkish construction industry. Although the number of green projects is increasing, this type of projects involves several material-related risks. The contractors, who undertake green projects, should be aware of these risks and take precautions against them in...