Enhancing life cycle cost analysis with a novel cost classification framework for pavement rehabilitation projects

Life cycle cost analysis (LCCA) procedures have been used over the past decades to justify the choice of one pavement design alternative over the others. However, many ambiguities associated with the life cycle cost input values, such as the discount rate and future cost estimates have questioned the credibility of the analysis results. Another unrecognized source of errors in pavement LCCA is the misunderstanding of pavement treatment costs when historical costs are typically used for estimating those costs. The historical costs of pavement rehabilitation projects typically include a significant amount of non-pavement-related costs, which may result in a wrong LCCA if not treated appropriately. This paper addresses this specific point of error and proposes a solution to eliminating this error by using a novel cost classification framework that successfully differentiates mainline roadway costs from non-pavement cost items. A case study using Monte Carlo simulation is conducted to evaluate the probabilistic LCCA results. The results of the case study indicate that the conventional approach of using total rehabilitation project costs in LCCA may even lead to a wrong investment decision. The findings of this study will help practitioners and researchers better understand the nature of pavement rehabilitation project cost distributions.     

A holistic approach to asset management in the Netherlands

The objective of the national agency for road and water infrastructure in the Netherlands is to deliver best service to the public at lowest life cycle cost, given public acceptable risk. This requires a sound and well-structured system of management and maintenance. Such a system consists of elements such as reliable asset data, long-term performance based maintenance programmes, clear steering objectives and transparent procurement strategies. Asset management will make it possible to show what network performance can be achieved, at which costs and with which associated risks. A model defining an asset owner role, an asset manager role and a service provider role was chosen as a governing principle for the design of the asset management process. The design of the process described in the paper sets the boundary conditions to carry out projects with the minimum amount of hindrance for the user while involving the market in the best possible way.     

论建设项目全寿命周期管理成本控制

阐述了建设项目全寿命周期的概念,对建设项目全寿命周期各阶段的管理内容进行了分析,从业主的角度探讨了建设项目全寿命周期管理成本控制的几项措施,从而有效降低建设项目全寿命周期成本。     

Quantifying and reducing uncertainty in life cycle assessment using the Bayesian Monte Carlo method

The traditional life cycle assessment (LCA) does not perform quantitative uncertainty analysis. However, without characterizing the associated uncertainty, the reliability of assessment results cannot be understood or ascertained. In this study, the Bayesian method, in combination with the Monte Carlo technique, is used to quantify and update the uncertainty in LCA results. A case study of applying the method to comparison of alternative waste treatment options in terms of global warming potential due to greenhouse gas emissions is presented. In the case study, the prior distributions of the parameters used for estimating emission inventory and environmental impact in LCA were based on the expert judgment from the intergovernmental panel on climate change (IPCC) guideline and were subsequently updated using the likelihood distributions resulting from both national statistic and site-specific data. The posterior uncertainty distribution of the LCA results was generated using Monte Carlo simulations with posterior parameter probability distributions. The results indicated that the incorporation of quantitative uncertainty analysis into LCA revealed more information than the deterministic LCA method, and the resulting decision may thus be different. In addition, in combination with the Monte Carlo simulation, calculations of correlation coefficients facilitated the identification of important parameters that had major influence to LCA results. Finally, by using national statistic data and site-specific information to update the prior uncertainty distribution, the resultant uncertainty associated with the LCA results could be reduced. A better informed decision can therefore be made based on the clearer and more complete comparison of options.     

Development of HVAC system simulation tool for life cycle energy management Part 1: Concept of life cycle energy management and outline of the developed simulation tool

The importance of LCEM (life cycle energy management) has been recognized from the view of life cycle energy savings for sustainable buildings. The purposes of this research are the proposal of an LCEM framework and development of prototype HVAC system simulation tools for LCEM. In this paper, the necessity of energy simulation tools for LCEM is discussed, and the outline and solution method of the simulation tool are shown.     

System reliability analysis by enhanced Monte Carlo simulation

The main focus of this paper is on the development of a Monte Carlo based method for estimating the reliability of structural systems. The use of Monte Carlo methods for system reliability analysis has several attractive features, the most important being that the failure criterion is usually relatively easy to check almost irrespective of the complexity of the system. The flip side of such methods is the amount of computational efforts that may be involved. However, by reformulating the reliability problem to depend on a parameter and exploiting the regularity of the failure probability as a function of this parameter, it is shown that a substantial reduction of the computational efforts involved can be obtained.     

Life cycle cost management of concrete structures relative to chloride-induced reinforcement corrosion

Chloride-induced reinforcement corrosion is one of the major causes for the deterioration of concrete structures. This article has developed a performance-based life cycle cost management (LCCM) model for reinforced concrete structures relative to corrosion deterioration. This model is characterised by three features: (1) a chloride-induced probabilistic corrosion deterioration mechanism is used to predict the service life of concrete structures; (2) the performance of a concrete structure is measured by serviceability limit states and structural capacity limit states; and (3) a dual management methodology is adopted, in which management actions are optimised to maximise the life cycle performance of a concrete structure under limited budget constraints and minimum required serviceability constraints. Case studies of bridge decks and piers are provided to demonstrate the application of the proposed performance-based LCCM model.     

Life cycle cost optimisation in highway concrete bridges management

This study presents a life cycle cost prediction and cost minimisation methodology for a set of highway concrete bridges, during a medium or a long period of time, in order to facilitate the decision process of the structure management. This methodology takes into consideration bridge intervention costs in addition with some Markov matrices degradation model. It applies a genetic algorithm in order to identify the optimised intervention plan, considering the available budget and the desired minimum performance level. Some Portuguese direct and indirect cost parameters, associated with different types of interventions during bridges lifetime, are presented. Finally, a probabilistic sensitivity analysis is carried out using Monte Carlo simulations.     

Integrated assessment method for building life cycle environmental and economic performance

Life cycle assessment (LCA) is a powerful tool to identify a building’s environmental impact throughout its life cycle. However, LCA does have limits in practice because it does not consider the economic aspect of project implementation. In order to promote LCA application, a more comprehensive evaluation of building life cycle environmental and economic performance must be performed. To address these issues, we propose life cycle green cost assessment (LCGCA), a method that combines LCA with life cycle costing (LCC). In LCGCA the building’s environmental loads are converted to environmental costs based on the trading price of CO₂ certified emission reductions (CERs). These environmental costs are then included into the building life cycle cost. Subsequently an evaluation index of green net present value (GNPV) for LCGCA can be obtained. A governmental office building in Beijing was studied using LCGCA. Several design options were compared and the sensitivity of the CER price was analyzed. The research also shows that conclusions reached by LCGCA may be different from those of traditional LCC, which does not include environmental costs. The application of LCGCA needs the support of environmental policies. A sound environmental tax mechanism is expected to be established in China soon, which will enable LCGCA to be a useful tool to guide sustainable building design efficiently.     

工程项目全生命周期造价集成管理系统设计

在全生命周期成本管理理论的基础上,从工程项目全生命周期出发,综合考虑项目的建造成本和运营与维护成本(使用成本),提出一个造价集成管理的系统设计方案。     

Monte Carlo simulation of the acceptance control of concrete

In the course of development of the Russian State Standard GOST 18105-86 “Concrete. Rules for Acceptance Control” the major concern was to ensure a prescribed level of structural reliability with minimum cement consumption. In order to achieve this goal, a new mathematical model of the acceptance control of concrete was suggested and on the basis of the model Monte Carlo simulation was performed. With the help of this technique different procedures of the acceptance control of concrete used in GOST 18105-86 were examined. The problems to determine within and between batch coefficients of variation, to specify minimum required strength of concrete, to check feasibility of batch rejection using minimum experimental value of concrete strength, to verify experimentally the GOST 18105-86 rules for acceptance control of concrete were stated and solved. The obtained results are included in GOST 18105-86.     

Monte Carlo simulation of wind velocity fields on complex structures

Monte Carlo simulation is becoming a fundamental tool for the design of complex and important wind-excited structures. A common application regards the time-domain dynamic analysis of multi-dof nonlinear structures whose excitation is calculated on the base of simulated wind velocity time-histories. The present paper describes a methodology for the simulation of wind velocity fields over large domains, possibly in zones characterised by complex topography. The modelling of turbulence in non-homogeneous flow condition and some computational aspects related to its simulation are discussed, proposing some strategies for reducing the calculation time. The simulation procedure is applied to the case of the Messina Strait bridge for which the three components of turbulence are simulated over a domain composed by 351 nodes.     

Water mains renewal planning framework for small to medium sized water utilities: a life cycle cost analysis approach

For the last few decades, concerns have repeatedly been raised about deteriorating water mains in Canada. Small to medium sized water utilities are generally impacted more due to lack of technical and financial resources. This paper presents a user-friendly life cycle cost (LCC) analysis-based decision support tool to help these utility managers to prioritize water mains rehabilitation or replacement (R/R) strategies. The deterioration curves for water mains of different materials and sizes have been developed based on their likelihood of failure. The proposed model is implemented for the water supply network of City of Kelowna (Canada). It compares the costs of various R/R scenarios for each pipe over its life cycle and suggests the most cost-effective decision to the managers to efficiently allocate their limited resources.     

如何加强施工项目成本管理

结合企业成本管理的现状和工作实际,运用成本预测、成本核算、成本分析、成本检查、成本考核等一系列方法和手段,就如何搞好施工企业项目成本管理作一探讨,以提高企业的经济效益。     

建设项目全寿命周期成本控制探析

一个建设项目,如何对项目前期决策至竣工的全过程进行有效地决策、控制和协调,在计划的投资范围内和预定的建设期限内,顺利完成建设任务并达到所要求的工程质量标准,创造尽可能大的有形和无形效益,已成为当前建筑行业迫切需要研究的重要课题。文章旨在通过分析建设项目全寿命周期下的成本控制,探讨各要素成本之间的相互关系,采用相应的措施,实现建设项目整个寿命周期成本最优化。     

浅谈建设项目全寿命周期成本控制

阐述了建设项目全寿命周期成本控制的意义,对全寿命周期成本控制的内涵、目的、性质、手段、内容等作了探讨,比较分析了全寿命周期成本控制与传统的决策、控制理论与方法的区别,指出了全寿命周期成本控制的措施。     

A Petri-Net-based modelling approach to railway bridge asset management

Management of a large portfolio of infrastructure assets is a complex and demanding task for transport agencies. Although extensive research has been conducted on probabilistic models for asset management, in particular bridges, focus has been almost exclusively on deterioration modelling. The model being presented in this study tries to reunite a disjointed system by combining deterioration, inspection and maintenance models. A Petri-Net modelling approach is employed and the resulting model consists of a number of different modules each with its own source of data, calibration methodology and functionality. The modules interconnect providing a robust framework. The interaction between the modules can be used to provide meaningful outputs useful to railway bridge portfolio managers.     

浅析建设工程项目的造价管理

通过对现有建设工程项目造价管理模式的分析,并在参考国际全面造价管理课题研究的基础上,提出了我国建设工程项目造价的全面管理模式,并且简述了各阶段对工程项目造价控制的方法,以提高工程项目管理水平。     

论施工项目成本管理

简述了施工项目成本管理的必然性,介绍了施工项目成本管理的原则,并对实施施工项目成本管理的途径和措施进行了探讨,最后指出了项目成本管理实施中需注意的问题,以提高施工企业的经济效益,从而使企业走向持续发展和良性循环的轨道。     

Effects of soil-foundation-structure interaction on seismic structural response via robust Monte Carlo simulation

Uncertainties involved in the characterization and seismic response of soil-foundation-structure systems along with the inherent randomness of the earthquake ground motion result in very complex (and often controversial) effects of soil-foundation-structure interaction (SFSI) on the seismic response of structures. Conventionally, SFSI effects have been considered beneficial (reducing the structural response), however, recent evidence from strong earthquakes has highlighted the possibility of detrimental effects or increase in the structural response due to SFSI. This paper investigates the effects of SFSI on seismic response of structures through a robust Monte Carlo simulation using a wide range of realistic SFS systems and earthquake input motions in time-history analyses. The results from a total of 1.36 million analyses are used to rigorously quantify the SFSI effects on structural distortion and total horizontal displacement of the structure, and to identify conditions (system properties and earthquake motion characteristics) under which SFSI increases the structural response.