مهندس گرشاسب خزاینی

Despite the expansion of public-private partnership in the world, the amount of private sector investment in Iran's infrastructure projects is lowe. In this article, the success factors of public-private partnership, specific to Iran's business environment, have been identified and their priority has been analyzed from the point of view of different stakeholders. By nominal group method, 23 success criteria of Iran's public-private partnership were identified and practical solutions to overcome them were proposed. The results of this research show that the most important success factors of public-private partnership in Iran include the project's profit rate, the employer's experience in project management, how to share risks between the two parties to the contract, and the transparency of the tender. The analysis of the results of the evaluations carried out by the private sector and the public sector in this article shows that there is a big difference between the priorities of the two parties. From the point of view of private sector, the main obstacle to public private participation in Iran is the adherence of executive bodies to contractual obligations. From the point of view of the public sector, the main priority against the development of public-private partnership is ambiguity in the laws and powers of public sector decision-makers. Therefore, it is suggested that by passing special laws for public-private partnership, while providing legal incentives and exemptions for financial support of private investors, efforts should be made to increase transparency in the decision-making process of the public sector.

The limitation of public resources to complete half-finished projects has ‎caused many government agencies and the public sector to focus on ‎attracting private investors, and numerous calls for attracting investors ‎through public-private partnership have been held in the country. But all ‎the projects defined for this method have not been successful and sometimes ‎they have faced failure and waste of high preparation costs. In this article, a ‎screening model has been developed that helps public sector employers to ‎determine the chance of project success before holding a call and provides ‎a tool for selecting projects in the organization's investment portfolio. For ‎this purpose, the success criteria of public-private partnership projects in ‎Iran were identified and categorized in the form of quantitative criteria. ‎Then, a multi-criteria decision-making model based on the TOPSIS model ‎has been developed, which can quantitatively measure the chance of success ‎of each project and finally select a portfolio of public-private partnership ‎projects based on the budget available to the client. The proposed model ‎has been implemented in order to select Tehran municipality projects in the ‎field of transportation and traffic. The results of the implementation of the ‎proposed model in an institution in charge of the public transportation field ‎show that the selection of the portfolio of investment projects, in addition to ‎paying attention to the limitation of the employer's resources, requires ‎considering certain features in the definition of projects and structuring the ‎employer's organization to manage collaborative projects that they to ‎attract private investors.‎

The limitation of budget resources to complete half-finished projects has caused a large number of government agencies and the public sector to monitor the attraction of private investors and to hold numerous calls to attract investors through public-private partnerships in the country. But all the projects defined for this method have not been successful and sometimes they have faced failure and waste of high preparation costs. In this article, a screening model has been developed that helps public sector employers to determine the chance of project success before holding a call and provides a tool for selecting projects in the organization's investment portfolio. For this purpose, the success criteria of public-private partnership projects in Iran were identified and categorized in the form of quantitative criteria. Then, a multi-criteria decision-making model based on the TOPSIS model has been developed, which can quantitatively measure the chance of success of each project and select projects based on the resilience of the business organization. The results of the implementation of the proposed model in several case projects in the field of urban transportation show that in order to achieve a balanced portfolio of public-private partnership projects, in addition to the characteristics of the project, the public sector must also pay attention to capacity building to accept more risks and control the social aspects of the project.

Risk allocation is a strategic decision in project management. But the ‎examination of the practical experience of managing construction projects ‎shows that the process of allocating risks is generally based on the personal ‎judgments of employers, so increases the cost and time of the project. The ‎purpose of this article is to provide a quantitative model for selecting the ‎optimal allocation of project risks, in a way that provides a balanced model ‎agreed upon by all contractual parties. To design the proposed model, by ‎analyzing the behavior characteristics and expectations of the employer in ‎the process of risk allocation, three goals: 1) transferring the risk to the most ‎capable agent, 2) paying the lowest cost of risk management and 3) ‎achieving the lowest level of risk for the employer. has been introduced. ‎Then, by developing quantitative functions to measure these three goals, a ‎multi-criteria decision model is presented that can measure the degree of ‎achievement of the employer's goals in different patterns of risk allocation. ‎By receiving the judgment of the decision maker in the form of qualitative ‎criteria, the proposed model evaluates different risk allocation options and ‎achieves the most appropriate project risk allocation pattern in the form of a ‎Pareto optimal curve. The proposed model in a A case study has been ‎implemented and its results have been compared with some of the most ‎widely used risk allocation models. The results of this model show that ‎achieving a balanced pattern of risk allocation that satisfies the interests of ‎all parties in the project requires attention to the conflicting goals of the ‎employer. While focusing on transferring the maximum risk to the other ‎party, it will increase the project costs and eventually not achieve other time ‎and financial goals of the project.‎

Project delivery systems, as the structure of the contract and the formation ‎of relations between the project ‎participants, create a framework for the ‎formation of contracts of different types of projects by allocating risk ‎‎among the project participants. Delivery systems can greatly affect the ‎time, financial, or quality goals of the ‎organization and are generally ‎classified into 5 categories: In house, Traditional, Design Build, Construct ‎‎management, and Public-Private Partnership (PPP). Each delivery system ‎has its own advantages and limitations, ‎which makes the choice between ‎them dependent on the project conditions and client's expectations. In this ‎article, ‎a new approach based on the allocation of contractual risks is ‎presented, with the help of which the employer can ‎choose the project ‎procurement system depending on the level of risk acceptable by the ‎employer. For this purpose, ‎by studying the records of risk allocation in ‎‎26 water projects in Iran, 14 main Contractual Risks have been ‎‎introduced, which are the basis of decision making for the project delivery ‎system. Based on his organizational ‎capacity in accepting a certain level ‎of 14 risks, the decision maker can select the appropriate delivery system ‎for ‎the project. Based on this approach, a multi-objective decision-making ‎model has been developed, which, by ‎receiving the project's risk profile, ‎quantitatively suggests the optimal structure and determines its level of ‎risks ‎exposure (in the form of an increase in the project's cost price). The ‎sensitivity analysis tool of this model also ‎guides the employer which ‎contractual tools or management capacities the employer should provide ‎in case of ‎using a specific contractual model.‎

Due to inadequate public financial status and increasing demand on infrastructure facilities, many governments worldwide are exploring new arrangements through Public Private Partnerships (PPP). However, PPP tenders are not feasible at all, but investors and developer may pay a lot of time and money for preparation for a tender that may not pay him back. Therefore private investors are seek a model to support them to decision whether bid or no bid in a PPP tender. This paper, present a decision support system based on MADM decision making models to evaluate Cost Opportunity of tenders. Utilizing the proposed model, private investors can rank the PPP tenders and select most tender with least cost opportunity. Deploying the proposed model in 11 Iranian PPP project in the field of water and power plant, prove that private investor decide to bid in a tender not only for fiscal attracters of project , but also they consider how public authority is organized and committed to government’s responsibilities. Public party can improve the success chance of PPP tenders by offering some incentive and advocate de-risking mechanisms.

Risk allocation, the definition and division of responsibility associated with a possible future loss or gain, seeks to assign responsibility for a variety of hypothetical circumstances should a project not proceed as planned. The result of improper risk allocation is increased costs, project delays and services which fail to deliver value-for-money to the community. A decision support system based on the graph model is presented for systematically resolving construction Risk Allocation. In this model mainly assumed success of a contract needs to agreement on how risks allocated by parties. The Risk Allocation analysis process considers the decision participants, their decision options, and their relative preferences when modeling the negotiation. This model is then used to perform an in-depth stability analysis in order to ascertain the possible compromise resolutions or equilibria. The model predicts the sequence of decisions that took place in the dispute and furnishes an array of useful strategic insights about the Risk Allocation. Moreover, a sensitivity analysis is executed to determine how changes in preferences can affect the equilibrium results. This Risk Allocation procedure is useful for both researchers and practitioners to better deal with the dispute-prone nature of the construction industry.

Nowadays, one of the main problems of human being is the protection of the environment against the presence of waste materials. Every year millions of tires are discarded, thrown away or buried all over the world. One of these waste materials, waste tires are. Wired tires are made of rubber particles and steel fibers. Past research has shown that rubber particles and recycled steel fiber from waste tire, can be used in concrete. This type of steel fibers can have a positive effect on the mechanical properties of concrete. Rubber particles in concrete reduce the compressive strength. In some studies, it has been shown that rubber particles increase or decrease the abrasion resistance of concrete, and even the size of the rubber particles also affect the abrasion resistance of concrete. In this research, simultaneous application of powder and crumb rubber, wire and recycled steel fibers from waste tire in concrete mixture, has been investigated to study the abrasion and compressive strengths and unit weight of concrete. In this research, in 12 mixing designs, replacing of powder and crumb rubber with sand to the amount 9%, 13.5%, 18%, 22.5% and 27% by volume of sand and adding 0.5% by volume of wire and recycled steel fibers from waste tire has been used. In all designs, the cement cutie is 380 and the ratio of water to cement is 0.47 constant. In this research, different samples are compared with the control sample. Compressive strength were performed after 7 and 28 days. Also, abrasive resistance and weight per unit volume were performed after 28 days. The results of the experiments show that rubber particles with a fine gradation will have a better impact on the abrasion resistance. But this is not so that about compressive strength and it reduces more resistance. Based on the results, adding 0.5% recycled steel fibers with a length ratio to high diameter to concrete containing 9% of powder and crumb rubber, reduction in compressive strength improves and cause increased abrasion resistance. But the adding steel wire to concrete containing powder and crumb rubber reduces the abrasion resistance. Use the powder and crumb rubber with 0.5% recycled steel fibers, reduces the compressive strength and by increasing the amount of powder and crumb rubber, reduction of resistance will be more. The abrasion resistance of concrete containing powder and crumb rubber with with 0.5% recycled steel fibers is increased relative to the control concrete. By increasing the powder and crumb rubber content, the abrasion resistance increases, but this upward trend occurs to a certain percentage of powder and crumb rubber replacement with sand, and then the percentage of increasing abrasion resistance decreases. By increasing the powder and crumb rubber, weight loss will be increased. From this perspective, it causes the lightness of concrete which can be the advantage of using these waste materials in concrete. The abrasion resistance of concrete containing 9% of powder and crumb rubber with 0.5% recycled steel fibers has increased up to 37.5% relative to the control concrete.

I n o r d e r t o t r a n s f e r r i s k s t o t h e m o s t c a p a b l e p a r t y a n d p r o v i d e a b a s i s f o r p r o j e c t p r o f i t s h a r i n g، r i s k a l l o c a t i o n h a s a s t r o n g i n f l u e n c e o n t h e t i m e a n d c o s t o f c o n s t r u c t i o n p r o j e c t s. I n t h i s p a p e r، f o r t h e f i r s t t i m e، a l l o c a t i o n o f r i s k t o t h e m o s t d e s e r v i n g p a r t y i s d e f i n e d a s a n o p t i m i z a t i o n p r o b l e m، a n d a q u a n t i t a t i v e m o d e l f o r r i s k a l l o c a t i o n o p t i m i z a t i o n i s i n t r o d u c e d. S i n c e t h e a i m o f r i s k a l l o c a t i o n i s d e f i n e d a s a c h i e v i n g p r o j e c t o b j e c t i v e s w i t h m a x i m u m r e l i a b i l i t y a n d m i n i m u m c o s t، i n t h e p r o p o s e d m o d e l، a n a p p l i c a b l e a n d l o g i c a l d e c i s i o n p a r a m e t e r i s i n t r o d u c e d a n d a n o p t i m i z a t i o n a l g o r i t h m، b a s e d o n t h e A n t C o l o n y O p t i m i z a t i o n (A C O) m e t h o d، i s d e v e l o p e d. T h e p r o p o s e d m o d e l a l s o p r o v i d e s a u s e f u l d e c i s i o n t o o l f o r t h e p r o j e c t o w n e r t o s e l e c t t h e b e s t i n s u r a n c e p a c k a g e b y i n c l u d i n g a s e n s i t i v i t y a n a l y s i s. I n o r d e r t o d e s i g n t h e A C O o p t i m i z a t i o n a l g o r i t h m o f t h e r i s k a l l o c a t i o n o p t i m i z a t i o n m o d e l; i n i t i a l l y، t h e o b j e c t i v e s o f o w n e r s w i t h i n t h e a l l o c a t i o n p r o c e s s a r e i d e n t i f i e d a n d t h e o b j e c t i v e f u n c t i o n i s d e f i n e d. W i t h r e s p e c t t o t h e o b j e c t i v e f u n c t i o n، t h e r i s k a l l o c a t i o n p r o b l e m i s t h e n r e s t r u c t u r e d a s a n o p t i m i z a t i o n p r o b l e m، a n d t h e d e c i s i o n p a r a m e t e r s، c o n s t r a i n t s a n d a f l o w c h a r t o f t h e m o d e l s t r u c t u r e a r e d e f i n e d. T h e s e p a r a m e t e r s a n d c o n s t r a i n t s a r e f o r m u l a t e d i n a m a t h e m a t i c a l e q u a t i o n; a n d a n o p t i m i z a t i o n a l g o r i t h m i s d e s i g n e d b a s e d o n A n t C o l o n y O p t i m i z a t i o n (A C O). B y r e c e i v i n g ``p r o f i t r e q u e s t e d f o r r i s k b e a r i n g b y e a c h p a r t i c i p a n t'' a s i n p u t، t h e p r o p o s e d m o d e l c a l c u l a t e s t h e c o s t o f r i s k m a n a g e m e n t f o r t h e o w n e r a n d t h e n m i n i m i z e s t h e o b j e c t i v e f u n c t i o n i n a n A n t C o l o n y O p t i m i z a t i o n a l g o r i t h m. T w o c o n s t r a i n t s a r e d e f i n e d a n d f o r m u l a t e d i n t h e p r o p o s e d m o d e l، i n o r d e r t o s i m u l a t e t h e r e a l d e c i s i o n p r o c e s s o f r i s k a l l o c a t i o n. A s f o l l o w s: 1) t h e m a x i m u m f i n a n c i a l c r e d i t o f e a c h p a r t y t o c o m p e n s a t e t h e c o n s e q u e n c e o f a n y r i s k a n d 2) t h e f i n a n c i a l a b i l i t y o f t h e o w n e r t o e n s u r e a g a i n s t r i s k e v e n t s. V a r y i n g t h i s c o n s t r a i n t، s e n s i t i v i t y a n a l y s i s w o u l d b e a v a i l a b l e i n t h e m o d e l t o o p t i m i z e t h e g u a r a n t e e p a c k a g e f o r t h e o w n e r. T h e r e f o r e، t h i s m o d e l c o u l d g u i d e t h e d e c i s i o n m a k e r t o w a r d s a d d r e s s i n g t h e m o s t e f f e c t i v e g u a r a n t e e s t o t h e b e s t p a r t y. T h i s m o d e l i s a p p l i e d i n a c a s e s t u d y t o p r e s e n t i t s c a p a b i l i t y a n d u s e f u l n e s s. A c c o r d i n g t o t h e f i n d i n g s o f t h e a p p l i e d p r o p o s e d m o d e l، i t c o u l d b e c o n c l u d e d t h a t r i s k s h a r i n g i n a p r o j e c t s h o u l d b e d o n e b a s e d o n p a r t y c o m p e t e n c y a n d w i l l i n g n e s s. I t i s a l s o c o n c l u d e d t h a t t h e o w n e r s h o u l d p a r t i c i p a t e i n t h e r i s k a l l o c a t i o n p r o c e s s i f h e/s h e w i s h e s t o a c h i e v e t h e b e s t r e l i a b i l i t y i n p r o j e c t o b j e c t i v e s w i t h m i n i m u m c o s t.

Application of Nano particles is recently shown a powerful potential to improve concrete specification. Few study has previously claimed that introducing little amount of nano particles could improve compressive strength and mechanical properties of concrete. However، these studies reported different and confusing mechanisms for nano effect and reaction that make difficult to developing and predicting other specification of nano concrete، especially durability specification. This paper aimed to study and identify the quality and interaction of these mechanisms، respect to mechanical properties. Laboratory tests and SEM survey is utilized in order to examination of microstructure of nano concrete. The findings of this study explain how and in whether nano particle effect on properties of concrete. It concluded that in the early age Nucleation effect of nano particle can explain the behavior of nano concretes; while by hydration developing، filing effect and pozolanic reaction have higher influence. Findings of this study are extremely agreed with mechanical properties of previous reports

An experimental investigation was carried out to improve the mechanical properties of transportation concrete containing nano SiO2 by varying cement content. Compressive and tensile strength of three different cement content, 350, 400 and 450 kg/cm3, was tested in the reference and nano contained concretes. SEM photos were also used for micro structural studies. The results have shown that change of cement content causes change in strength of specimens in a convex manner with a maximum point. The addition of nano silica resulted in shifting this curve to higher cement content while the shape of curve was saved. Therefore with nano silica particles; the concrete can achieve higher strength in superior cement content. SEM observations have confirmed that nano silica can improve microstructure of concrete by decreasing the size and amount of crystals and reducing pores distribution. As observed in SEM studies, more uniform texture that produced by nano particles may put a stop to micro crack development and facilitate higher compressive and tensile strength, despite of increasing cement content.

The influence of cement content increase on corrosion resistant behavior in concretes containing nano-SiO2 was experimentally studied. For comparison, the chloride diffusion of plain concrete and the concrete containing nano-SiO2 was also experimentally studied. The test results indicated that the corrosion resistance of concretes containing nano-particles is significantly improved. However, the index of diffusion chloride ion in the concretes containing nano-SiO2 is directly related to cement content in the mix. The SEM oservations revealed that the microstructure of concrete with nano-SiO2 is more uniform and compact than that of normal concrete, but higher pore size distribution was observed when cement content is increased, which in turn leads to the increase in the diffusion of choloride ion.