Tahir Çelik - Academia.edu (original) (raw)
Papers by Tahir Çelik
Computers & Electrical Engineering, Oct 1, 2022
Environmental Earth Sciences, Feb 1, 2021
Due to urban development worldwide, disposing sewage sludge (SS) has become a major concern for m... more Due to urban development worldwide, disposing sewage sludge (SS) has become a major concern for many countries. SS produced from the New Waste Water Treatment Plant (NWWTP) in Nicosia has not been used for soil application as it was planned since late 2013 due to absence of legislations regarding this route. This issue has been and still a major concern for of Nicosia Turkish Municipality and its society for many years. This study investigates the potential use of SS as construction material by producing an artificial lightweight aggregate (ALWA) and cement replacement material. Fine dry sludge (FDS) and sewage sludge ash (SSA) were used as raw materials for ALWA production. FDS was incinerated at 850 °C for 1 and 2 h to produce SSA1 and SSA2, respectively. Both SSA1 and SSA2 were mixed separately with FDS in different proportions and incinerated at 1100 °C to produce lightweight aggregate AG1 and AG2, respectively. Potential use of SSA1 and SSA2 as cement replacement materials was assessed by measuring the Pozzolanic activity of both ashes throughout physical and chemical tests. It was found out that increasing amount of FDS reduced specific gravity of AG1 and AG2, while increasing amount SSA in the mix improved the surface texture and increased the specific gravity of both AG1 and AG2. Results also indicated that both SSA1 and SSA2 have Pozzolanic properties based in all tests performed. Therefore, using sewage sludge produced from the NWWTP in Nicosia as a sustainable construction material is potential and this could extend the disposal route of the sludge and resolve the accumulation problem in Nicosia.
Expert Systems With Applications, Apr 1, 1998
Building design and material type used are the two main parameters that have a significant impact... more Building design and material type used are the two main parameters that have a significant impact on the cost of a building. Therefore, it is important for a cost estimating tool to have a mechanism that allows the designer to perform a rapid 'what if' analysis on design alternatives and materials selection at the early planning stage without the accompaniment of detailed design and drawings. However, the traditional design cost estimating procedures generally focus on assessing costs after design decisions are made and conveyed to the construction drawing as a quantity take off. On the other hand, comparative cost estimating (unit cost per square meter) uses historical data collected by averaging buildings of different designs, heights and materials. Even today's computer aided design (CAD) software incorporates a mechanism to take off quantities from completed designs and drawings. However, basically they are the same as the traditional quantity take off estimating because a single specified design still controls the resulting costs, and there is no alternative materials selection integrated to the cost system. This article presents an integrated knowledge-based system for alternative design decisions, materials selection and cost estimating mainly for pre-design analysis. The knowledge-based system also includes materials selection and cost estimating for afterdetailed design by providing edit tables for inputting the dimensions of building elements from completed designs and drawings or by directly importing from CAD. The system generates activities quantities, costs and lists of materials selected and their respective quantities. An analysis of alternative design and materials selection for a residential building using the integrated system is presented.
Expert Systems With Applications, Oct 1, 2001
Marginal value of a building is the subjective part of the value of the constructed facility and ... more Marginal value of a building is the subjective part of the value of the constructed facility and depends on how the decisions made by the contributing parties at different stages of the implementation of the project of a building. To increase the marginal value of a building, decisions made during the stages of a project need to be in close agreement with the value criteria of the decisions. Traditionally, during the implementation of a building project designers and clients make decisions with a little knowledge of the effects contributed by the decisions on the value the constructed facility. Knowledge of decisions to be made during the stages of a building project, value criteria of the decisions and their effects on the value of the constructed facility are important for successful project implementation. Therefore, determination of marginal value of a construction project lends itself to a knowledge-based application. This paper presents a knowledge-based system called COMVOB for the determination of the marginal value of a building project. To the user COMVOB presents criteria of decisions together with their importance weights at stages of a building project and with the input and con®rmation of the details of the decisions it reports anticipated positive and negative marginal values.
Knowledge Based Systems, Mar 1, 2002
... Because forming schedule manually is very costly and time consuming the scheduler cannot perf... more ... Because forming schedule manually is very costly and time consuming the scheduler cannot perform several schedule alternative to evaluate time integrated cost that indicate the timing of capital needs for the design decisions and construction methods selection. ...
Cement and Concrete Research, Jul 1, 1996
... Once the effects of crushed stone dust on concrete properties are obtained, it will be possib... more ... Once the effects of crushed stone dust on concrete properties are obtained, it will be possible to take necessary measures to alleviate its adverse effects on concrete. Experimental Program Materials. In all mixes limestone crushed rock coarse and fine aggregates were used. ...
Expert Systems With Applications, Jul 1, 1998
Value of a product, such as a component of a building, reflects an owner's desire to retain and o... more Value of a product, such as a component of a building, reflects an owner's desire to retain and obtain the product, and this introduces subjective aspects to the value. The value of a constructed facility depends on how much the design details of its components agree with the value system of the client. Traditionally, selection of design details is performed by the designers with little consultation with the client. A successful selection of components of construction needs a knowledge of design alternatives, components' criteria and utilities and agreement with the value system of the client. Therefore, determination of value of a constructed facility lends itself to a knowledge based application. This paper presents a knowledge based system called VOBE for the determination of the value of the envelope of a residential building based on the client's value system. To the user VOBE presents design alternative details for each component of the envelope and with the input/confirmation of his/her value system it reports the costs and values of the components of the building envelope.
Teknik Dergi, Nov 1, 2021
One of the most common concern in construction projects is changes during execution. Changes can ... more One of the most common concern in construction projects is changes during execution. Changes can increase the cost and duration of the construction project hereby, can lead to conflict between the parties involved in construction projects. Causes of the changes may differ depending on the organizations and regions characteristics. The aim of this study is to investigate the impact of organizational and regional characteristics on key change factors. In this regard, top risky change factors were identified with respect to contractors, consultants, and owners located in North Cyprus, Turkey, and the U.S.A. The research findings showed that the most risky change factors differed in accordance with the characteristics of organizations and regions. It was concluded that "Errors/Inadequacies in Contract Drawing" was the riskiest factor according to contractors while "Low price due to high competition" was noted to be the riskiest change causes with respect to consultants and owners. If different countries were compared, "Inconsistency between different design disciplines" was identified as the top risky change factor according to the respondents in the U.S.A. located organizations, but "Low contract price" was designated as the top risky change factor according to the respondents in North Cyprus and Turkey. In addition, key measures were suggested to mitigate changes in accordance with organizational and regional characteristics.
Materiales De Construccion, Jun 30, 2001
Relación entre la tenacidad a flexión y la energía de impacto en hormigones de alta resistencia r... more Relación entre la tenacidad a flexión y la energía de impacto en hormigones de alta resistencia reforzados con fibras (HSFRC) Relationship between flexural toughness energy and impact energy of high strength fiber reinforced concrete (HSFRC)
Journal of Testing and Evaluation, 1999
There are many test methods to measure the impact resistance of fiber-reinforced concrete that ar... more There are many test methods to measure the impact resistance of fiber-reinforced concrete that are complicated, time consuming, and expensive. A practical test method has been developed to measure the impact resistance of high-strength fiber-reinforced concrete (HSFRC). The equipment developed can also be used for testing aggregate impact values by simply changing the base plate of the machine. A machine was developed to measure the surface abrasion resistance of HSFRC. Testing fiber-reinforced concrete for surface abrasion resistance was found to be extremely difficult if realistic and practical results were desired. In this study the influence of silica fume on the properties of HSFRC was investigated by using silica fume at two different percentages and with three different hooked-end fibers, namely, 30/0.50, 60/0.80, and 50/0.60 length/diameter (mm/mm). Fibers were added to concrete in three different percentages of 0.5, 1.0, and 2.0% by volume of concrete. The results show that including fibers in high-strength concrete improves impact resistance, surface abrasion, and splitting tensile strength.
There is great scope for problems and deficiencies in the workmanship of concreting operations na... more There is great scope for problems and deficiencies in the workmanship of concreting operations namely. batching. mixing. transporting. placing. compacting. finishing and curing. These problems will adversely affect the quality of the finished concrete. Improving the knowledge and experience of the supervisory staff and workmen on construction sites is essential if these defiCiencies are to be minimized. It has been observed that specifications for concreting activities contain insufficient information regarding workmanship. This causes difficulties in controlling the concreting operations. This thesis addresses the problems associated with the transfer of knowledge from acknowledged experts in concreting operations to site practitioners. It is proposed that an appropriate tool for this information transfer is the use of computer based expert systems. Therefore, an expert system. called ESCON. has been developed to advise on concreting activities. The knowledge of this system was acquired from technical literature, site visits, self experience, and by interviewing experts in the domain. ESCON is capable of: 1) defining and diagnosing concreting problems; 2) giving expert recommendations for the solution of these problems. including the reasons behind the solution; 3) educating inexperienced staff by improving their appreciation of the domain; 4) preparing comprehensive specifications including information on the. workmanship requirements of concreting procedures; 5) calculating the expected loss in the strength of concrete when recommendations are ignored. Experimental work was undertaken at CRIB (Construction Industry Training Board), Bircham Newton, Norfolk, to assist in the verification of the model. The model was tested by undertaking five evaluation methods, including comparison of the result with an objective standard, sensitivity analysis, expert's experience, novice users, and a real life case study.
A knowledge based expert system for modelling the production of conventional concrete is describe... more A knowledge based expert system for modelling the production of conventional concrete is described, which was developed to help improve the quality of concrete by minimizing mistakes and deficiencies in batching and mixing procedures. The paper describes a study of concrete batching and mixing methods and practices in conventional concrete technology, and of the decisions made by personnel involved in concrete production. The details are described of the computer program, ESCON. The knowledge acquisition for ESCON is described. ESCON is now being improved nd extended to cover other concrete operations such as transporting, placing, etc.
Engineering, Construction and Architectural Management, Apr 18, 2023
The aim of this report is to evaluate 4 different options for exporting Cyprus’s natural gas - re... more The aim of this report is to evaluate 4 different options for exporting Cyprus’s natural gas - regardless of how the political issues between the Greek Cypriots and the Turkish Cypriots are tackled – from the Life Cycle Cost Benefit (LCCBA) perspective. These options are: - LNG (Liquefied Natural Gas) - CNG (Compressed Natural Gas) - Pipeline - GtW (Gas to Wire) The result shown the CNG and pipeline to be most favorable considering NPV, IRR and also geopolitical positioning of Cyprus.
Oil and Gas Journal
Pipeline and CNG are the best options for exporting natural gas production from Cyprus to relativ... more Pipeline and CNG are the best options for exporting natural gas production from Cyprus to relatively close markets in terms of both initial cost and probable benefits. LNG, meanwhile, would only be cost-effective if exported to higher priced Asian markets. Preliminary exploration drilling indicates estimated natural gas reserves in Block 13 of the Aphrodite basin of 3.1 tcf. Aphrodite basin is adjacent to the estimated 122-tcf Levant basin (Fig. 1). The other 12 Aphrodite blocks inside Cyprus's exclusive economic zone (EEZ) require further exploration but offer the potential of still more reserves... http://www.ogj.com/articles/print/volume-112/issue-11/transportation/pipeline-cng-top-cyprus-gas-export-options.html
Computers and Electrical Engineering
Computers & Electrical Engineering, Oct 1, 2022
Environmental Earth Sciences, Feb 1, 2021
Due to urban development worldwide, disposing sewage sludge (SS) has become a major concern for m... more Due to urban development worldwide, disposing sewage sludge (SS) has become a major concern for many countries. SS produced from the New Waste Water Treatment Plant (NWWTP) in Nicosia has not been used for soil application as it was planned since late 2013 due to absence of legislations regarding this route. This issue has been and still a major concern for of Nicosia Turkish Municipality and its society for many years. This study investigates the potential use of SS as construction material by producing an artificial lightweight aggregate (ALWA) and cement replacement material. Fine dry sludge (FDS) and sewage sludge ash (SSA) were used as raw materials for ALWA production. FDS was incinerated at 850 °C for 1 and 2 h to produce SSA1 and SSA2, respectively. Both SSA1 and SSA2 were mixed separately with FDS in different proportions and incinerated at 1100 °C to produce lightweight aggregate AG1 and AG2, respectively. Potential use of SSA1 and SSA2 as cement replacement materials was assessed by measuring the Pozzolanic activity of both ashes throughout physical and chemical tests. It was found out that increasing amount of FDS reduced specific gravity of AG1 and AG2, while increasing amount SSA in the mix improved the surface texture and increased the specific gravity of both AG1 and AG2. Results also indicated that both SSA1 and SSA2 have Pozzolanic properties based in all tests performed. Therefore, using sewage sludge produced from the NWWTP in Nicosia as a sustainable construction material is potential and this could extend the disposal route of the sludge and resolve the accumulation problem in Nicosia.
Expert Systems With Applications, Apr 1, 1998
Building design and material type used are the two main parameters that have a significant impact... more Building design and material type used are the two main parameters that have a significant impact on the cost of a building. Therefore, it is important for a cost estimating tool to have a mechanism that allows the designer to perform a rapid 'what if' analysis on design alternatives and materials selection at the early planning stage without the accompaniment of detailed design and drawings. However, the traditional design cost estimating procedures generally focus on assessing costs after design decisions are made and conveyed to the construction drawing as a quantity take off. On the other hand, comparative cost estimating (unit cost per square meter) uses historical data collected by averaging buildings of different designs, heights and materials. Even today's computer aided design (CAD) software incorporates a mechanism to take off quantities from completed designs and drawings. However, basically they are the same as the traditional quantity take off estimating because a single specified design still controls the resulting costs, and there is no alternative materials selection integrated to the cost system. This article presents an integrated knowledge-based system for alternative design decisions, materials selection and cost estimating mainly for pre-design analysis. The knowledge-based system also includes materials selection and cost estimating for afterdetailed design by providing edit tables for inputting the dimensions of building elements from completed designs and drawings or by directly importing from CAD. The system generates activities quantities, costs and lists of materials selected and their respective quantities. An analysis of alternative design and materials selection for a residential building using the integrated system is presented.
Expert Systems With Applications, Oct 1, 2001
Marginal value of a building is the subjective part of the value of the constructed facility and ... more Marginal value of a building is the subjective part of the value of the constructed facility and depends on how the decisions made by the contributing parties at different stages of the implementation of the project of a building. To increase the marginal value of a building, decisions made during the stages of a project need to be in close agreement with the value criteria of the decisions. Traditionally, during the implementation of a building project designers and clients make decisions with a little knowledge of the effects contributed by the decisions on the value the constructed facility. Knowledge of decisions to be made during the stages of a building project, value criteria of the decisions and their effects on the value of the constructed facility are important for successful project implementation. Therefore, determination of marginal value of a construction project lends itself to a knowledge-based application. This paper presents a knowledge-based system called COMVOB for the determination of the marginal value of a building project. To the user COMVOB presents criteria of decisions together with their importance weights at stages of a building project and with the input and con®rmation of the details of the decisions it reports anticipated positive and negative marginal values.
Knowledge Based Systems, Mar 1, 2002
... Because forming schedule manually is very costly and time consuming the scheduler cannot perf... more ... Because forming schedule manually is very costly and time consuming the scheduler cannot perform several schedule alternative to evaluate time integrated cost that indicate the timing of capital needs for the design decisions and construction methods selection. ...
Cement and Concrete Research, Jul 1, 1996
... Once the effects of crushed stone dust on concrete properties are obtained, it will be possib... more ... Once the effects of crushed stone dust on concrete properties are obtained, it will be possible to take necessary measures to alleviate its adverse effects on concrete. Experimental Program Materials. In all mixes limestone crushed rock coarse and fine aggregates were used. ...
Expert Systems With Applications, Jul 1, 1998
Value of a product, such as a component of a building, reflects an owner's desire to retain and o... more Value of a product, such as a component of a building, reflects an owner's desire to retain and obtain the product, and this introduces subjective aspects to the value. The value of a constructed facility depends on how much the design details of its components agree with the value system of the client. Traditionally, selection of design details is performed by the designers with little consultation with the client. A successful selection of components of construction needs a knowledge of design alternatives, components' criteria and utilities and agreement with the value system of the client. Therefore, determination of value of a constructed facility lends itself to a knowledge based application. This paper presents a knowledge based system called VOBE for the determination of the value of the envelope of a residential building based on the client's value system. To the user VOBE presents design alternative details for each component of the envelope and with the input/confirmation of his/her value system it reports the costs and values of the components of the building envelope.
Teknik Dergi, Nov 1, 2021
One of the most common concern in construction projects is changes during execution. Changes can ... more One of the most common concern in construction projects is changes during execution. Changes can increase the cost and duration of the construction project hereby, can lead to conflict between the parties involved in construction projects. Causes of the changes may differ depending on the organizations and regions characteristics. The aim of this study is to investigate the impact of organizational and regional characteristics on key change factors. In this regard, top risky change factors were identified with respect to contractors, consultants, and owners located in North Cyprus, Turkey, and the U.S.A. The research findings showed that the most risky change factors differed in accordance with the characteristics of organizations and regions. It was concluded that "Errors/Inadequacies in Contract Drawing" was the riskiest factor according to contractors while "Low price due to high competition" was noted to be the riskiest change causes with respect to consultants and owners. If different countries were compared, "Inconsistency between different design disciplines" was identified as the top risky change factor according to the respondents in the U.S.A. located organizations, but "Low contract price" was designated as the top risky change factor according to the respondents in North Cyprus and Turkey. In addition, key measures were suggested to mitigate changes in accordance with organizational and regional characteristics.
Materiales De Construccion, Jun 30, 2001
Relación entre la tenacidad a flexión y la energía de impacto en hormigones de alta resistencia r... more Relación entre la tenacidad a flexión y la energía de impacto en hormigones de alta resistencia reforzados con fibras (HSFRC) Relationship between flexural toughness energy and impact energy of high strength fiber reinforced concrete (HSFRC)
Journal of Testing and Evaluation, 1999
There are many test methods to measure the impact resistance of fiber-reinforced concrete that ar... more There are many test methods to measure the impact resistance of fiber-reinforced concrete that are complicated, time consuming, and expensive. A practical test method has been developed to measure the impact resistance of high-strength fiber-reinforced concrete (HSFRC). The equipment developed can also be used for testing aggregate impact values by simply changing the base plate of the machine. A machine was developed to measure the surface abrasion resistance of HSFRC. Testing fiber-reinforced concrete for surface abrasion resistance was found to be extremely difficult if realistic and practical results were desired. In this study the influence of silica fume on the properties of HSFRC was investigated by using silica fume at two different percentages and with three different hooked-end fibers, namely, 30/0.50, 60/0.80, and 50/0.60 length/diameter (mm/mm). Fibers were added to concrete in three different percentages of 0.5, 1.0, and 2.0% by volume of concrete. The results show that including fibers in high-strength concrete improves impact resistance, surface abrasion, and splitting tensile strength.
There is great scope for problems and deficiencies in the workmanship of concreting operations na... more There is great scope for problems and deficiencies in the workmanship of concreting operations namely. batching. mixing. transporting. placing. compacting. finishing and curing. These problems will adversely affect the quality of the finished concrete. Improving the knowledge and experience of the supervisory staff and workmen on construction sites is essential if these defiCiencies are to be minimized. It has been observed that specifications for concreting activities contain insufficient information regarding workmanship. This causes difficulties in controlling the concreting operations. This thesis addresses the problems associated with the transfer of knowledge from acknowledged experts in concreting operations to site practitioners. It is proposed that an appropriate tool for this information transfer is the use of computer based expert systems. Therefore, an expert system. called ESCON. has been developed to advise on concreting activities. The knowledge of this system was acquired from technical literature, site visits, self experience, and by interviewing experts in the domain. ESCON is capable of: 1) defining and diagnosing concreting problems; 2) giving expert recommendations for the solution of these problems. including the reasons behind the solution; 3) educating inexperienced staff by improving their appreciation of the domain; 4) preparing comprehensive specifications including information on the. workmanship requirements of concreting procedures; 5) calculating the expected loss in the strength of concrete when recommendations are ignored. Experimental work was undertaken at CRIB (Construction Industry Training Board), Bircham Newton, Norfolk, to assist in the verification of the model. The model was tested by undertaking five evaluation methods, including comparison of the result with an objective standard, sensitivity analysis, expert's experience, novice users, and a real life case study.
A knowledge based expert system for modelling the production of conventional concrete is describe... more A knowledge based expert system for modelling the production of conventional concrete is described, which was developed to help improve the quality of concrete by minimizing mistakes and deficiencies in batching and mixing procedures. The paper describes a study of concrete batching and mixing methods and practices in conventional concrete technology, and of the decisions made by personnel involved in concrete production. The details are described of the computer program, ESCON. The knowledge acquisition for ESCON is described. ESCON is now being improved nd extended to cover other concrete operations such as transporting, placing, etc.
Engineering, Construction and Architectural Management, Apr 18, 2023
The aim of this report is to evaluate 4 different options for exporting Cyprus’s natural gas - re... more The aim of this report is to evaluate 4 different options for exporting Cyprus’s natural gas - regardless of how the political issues between the Greek Cypriots and the Turkish Cypriots are tackled – from the Life Cycle Cost Benefit (LCCBA) perspective. These options are: - LNG (Liquefied Natural Gas) - CNG (Compressed Natural Gas) - Pipeline - GtW (Gas to Wire) The result shown the CNG and pipeline to be most favorable considering NPV, IRR and also geopolitical positioning of Cyprus.
Oil and Gas Journal
Pipeline and CNG are the best options for exporting natural gas production from Cyprus to relativ... more Pipeline and CNG are the best options for exporting natural gas production from Cyprus to relatively close markets in terms of both initial cost and probable benefits. LNG, meanwhile, would only be cost-effective if exported to higher priced Asian markets. Preliminary exploration drilling indicates estimated natural gas reserves in Block 13 of the Aphrodite basin of 3.1 tcf. Aphrodite basin is adjacent to the estimated 122-tcf Levant basin (Fig. 1). The other 12 Aphrodite blocks inside Cyprus's exclusive economic zone (EEZ) require further exploration but offer the potential of still more reserves... http://www.ogj.com/articles/print/volume-112/issue-11/transportation/pipeline-cng-top-cyprus-gas-export-options.html
Computers and Electrical Engineering