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Failure of irregular rock samples may provide implications in the rapid estimation of rock strength, which is imperative in rock engineering practice. In this work, analytical, experimental and numerical investigations were carried out to study the mechanical properties and failure characteristics of rock spheres under paired point loads. Analytical solutions indicted that with the increase in sample size (contact angle) and decrease in Poisson's ratio, the uneven tensile stress in theta direction decreased. Then laboratory experiments were carried out to investigate the load characteristics and failure mode of spherical marble samples with different sizes subjected to a pair of diametral point loads. The discrete element method (DEM) was adopted to study the failure process of rock spheres. The effect of the sphere diameter on the point load contact angle was examined in terms of peak load, crushed zone distribution and energy dissipation. Experimental and numerical results showed that the samples primarily fail in tension, with crushed zones formed at both loading points. With increase in the sample size, the contact angle, crushed area and total work increase. As the specimen diameter increases from 30 mm to 50 mm, the peak load on the specimen increases from 3.6 kN to 8.8 kN, and the percentage of crushed zone (ratio of crushing zone to sample radius, d/r) increased from 0.191 to 0.262. The results of the study have implications for understanding the failure of irregular rock specimens under point loading conditions and their size effects.

The goal of this study is to identify, classify, explore, and understand decision-making complexity elements in major infrastructure projects (MIPs). This article puts forward systematic definitions of decision making, decision-making quality, and decision-making complexity. Based on literature reviews and an in-depth case analysis of Hong Kong-Zhuhai-Macao Bridge (HZMB), a comprehensive framework of decision-making complexity is developed, which divides the elements into six dimensions: technical, social, financial, legal, organizational, and time. The links between different dimensions are also illustrated. This article is expected to deepen our current understanding of decision-making complexity and to provide a fundamental point of reference in the front-end phase of MIPs., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Integral Design and Management

The goal of this study is to identify, classify, explore, and understand decision-making complexity elements in major infrastructure projects (MIPs). This article puts forward systematic definitions of decision making, decision-making quality, and decision-making complexity. Based on literature reviews and an in-depth case analysis of Hong Kong-Zhuhai-Macao Bridge (HZMB), a comprehensive framework of decision-making complexity is developed, which divides the elements into six dimensions: technical, social, financial, legal, organizational, and time. The links between different dimensions are also illustrated. This article is expected to deepen our current understanding of decision-making complexity and to provide a fundamental point of reference in the front-end phase of MIPs., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Integral Design & Management

In the process of internationalization of construction contractors, international enterprises as main contractors (IMC) need to consider whether part of the contract should be subcontracted to local subcontractors (LSC) to gain a competitive advantage when competing with local main contractors (LMC). The involvement of local subcontractors can usually help reduce cost through the cost spillover effect. However, it should be noted that the share of local subcontractors with local main contractors with an inferior quality may lead to quality spillover. The Hotelling model is therefore adopted to investigate the subcontracting decisions of main contractors considering both cost and quality spillover effects. Many scenarios are simulated and the results show that LMCs with inferior quality can always choose the subcontracting strategy to obtain increased profit regardless of the strategy that IMCs adopt. On the other hand, IMCs need to balance the cost spillover of subcontracting and the quality spillover for improving the quality level of LSCs. The results are useful for contractors to make decisions that are relevant to the adoption of subcontracting strategies to obtain competitive advantages., Integral Design and Management

The large scale of construction in mega projects leads to significant environmental and socioeconomic impacts; thus, the projects should also exhibit greater social responsibility. Adopting green supply chain management in the construction process is an important way to realize the goal of sustainable development of mega projects. Because the green supply chain behavior during construction is mainly demonstrated by contractors, it is especially important to study the evolutionary trend of their behavior. Thus, to explore the cooperative relationship among contractors, this paper considers a lengthy construction period, multi-agent participation dynamics, and opportunistic behavior-all are key features of mega projects-and establishes an evolutionary game model. Specifically, a replicator dynamic equation is used to describe the long-term effects of the contractor's decisions. Equilibrium determinants are then analyzed and simulated. The results show that the initial probabilities of the two types of contractors (main contractor and subcontractor) demonstrating opportunistic behaviors have a significant effect on the direction of evolution of the mega project. The main contractor, who dominates the subsidy allocation by the government and project owner, should pay attention to maintaining a balance in the income distribution between him or her and the subcontractor. Additionally, there is an optimal distribution coefficient for the subsidy that minimizes the overall probability of opportunistic behavior. This paper provides a point of reference for the decisions of the main contractor and the subcontractor in the green supply chain of mega projects., Integral Design and Management

As one of the most important sustainability project management practices, prefabrication has been drawing increasing attention to project construction practitioners. However, due to the needs of high technology and large capital investment, there is a great challenge for suppliers to adopt prefabrication in mega project construction. Therefore, designing an adequate incentive mechanism has become a daunting task for the project owner, which aims to ensure a socially and environmentally friendly project delivery. In this study, an incentive model with reputational concerns from the perspective of the project owner was established and how this incentive affects supplier's effort and project owner's profit was investigated. By contrasting to the incentive model without reputational concerns, when the reputation incentive is considered in the incentive contract, both supplier's effort and project owner's profit increase. In addition, adding reputation incentive implies more expenses, thus the project owner may not want to take this strategy due to the potential expense increase. Therefore, the study also considered an incentive mechanism with constant total incentive intensity. By comparison, the result shows that this strategy is also useful which can improve supplier's effort and project owner's profit., Integral Design and Management

In the process of internationalization of construction contractors, international enterprises as main contractors (IMC) need to consider whether part of the contract should be subcontracted to local subcontractors (LSC) to gain a competitive advantage when competing with local main contractors (LMC). The involvement of local subcontractors can usually help reduce cost through the cost spillover effect. However, it should be noted that the share of local subcontractors with local main contractors with an inferior quality may lead to quality spillover. The Hotelling model is therefore adopted to investigate the subcontracting decisions of main contractors considering both cost and quality spillover effects. Many scenarios are simulated and the results show that LMCs with inferior quality can always choose the subcontracting strategy to obtain increased profit regardless of the strategy that IMCs adopt. On the other hand, IMCs need to balance the cost spillover of subcontracting and the quality spillover for improving the quality level of LSCs. The results are useful for contractors to make decisions that are relevant to the adoption of subcontracting strategies to obtain competitive advantages., Integral Design & Management

As one of the most important sustainability project management practices, prefabrication has been drawing increasing attention to project construction practitioners. However, due to the needs of high technology and large capital investment, there is a great challenge for suppliers to adopt prefabrication in mega project construction. Therefore, designing an adequate incentive mechanism has become a daunting task for the project owner, which aims to ensure a socially and environmentally friendly project delivery. In this study, an incentive model with reputational concerns from the perspective of the project owner was established and how this incentive affects supplier's effort and project owner's profit was investigated. By contrasting to the incentive model without reputational concerns, when the reputation incentive is considered in the incentive contract, both supplier's effort and project owner's profit increase. In addition, adding reputation incentive implies more expenses, thus the project owner may not want to take this strategy due to the potential expense increase. Therefore, the study also considered an incentive mechanism with constant total incentive intensity. By comparison, the result shows that this strategy is also useful which can improve supplier's effort and project owner's profit., Integral Design & Management

The large scale of construction in mega projects leads to significant environmental and socioeconomic impacts; thus, the projects should also exhibit greater social responsibility. Adopting green supply chain management in the construction process is an important way to realize the goal of sustainable development of mega projects. Because the green supply chain behavior during construction is mainly demonstrated by contractors, it is especially important to study the evolutionary trend of their behavior. Thus, to explore the cooperative relationship among contractors, this paper considers a lengthy construction period, multi-agent participation dynamics, and opportunistic behavior-all are key features of mega projects-and establishes an evolutionary game model. Specifically, a replicator dynamic equation is used to describe the long-term effects of the contractor's decisions. Equilibrium determinants are then analyzed and simulated. The results show that the initial probabilities of the two types of contractors (main contractor and subcontractor) demonstrating opportunistic behaviors have a significant effect on the direction of evolution of the mega project. The main contractor, who dominates the subsidy allocation by the government and project owner, should pay attention to maintaining a balance in the income distribution between him or her and the subcontractor. Additionally, there is an optimal distribution coefficient for the subsidy that minimizes the overall probability of opportunistic behavior. This paper provides a point of reference for the decisions of the main contractor and the subcontractor in the green supply chain of mega projects., Integral Design & Management