Delay Analysis Method Using Delay Section

The most common cause of construction claims is delay. Moreover, delay claims are often extremely complex and difficult to resolve. For this reason, the construction industry requires an effective and reliable method for analyzing the causes and effects of construction delay. Presently, the methods of analysis in common use do not adequately account for several commonly encountered situations. As a result, project time extensions are often considered without rigorous analysis. Therefore the objective of this study is to propose and describe an effective and logical method for evaluating construction delays that adequately accounts for commonly encountered situations. To achieve this objective, the writers propose a new methodology called “delay analysis method using delay section” (DAMUDS) as a means of overcoming two limitations of existing methods: (1) inadequate accounting of concurrent delay and (2) inadequate accounting of time-shortened activities. The DAMUDS method builds upon the widely used method of contemporaneous period analysis. The writers’ points are illustrated through the use of an example case.     

Delay Analysis within Construction Contracting Organizations

Delayed completion of a construction project is often caused by a complex interaction of a combination of events, some of which are the contractor’s risks and others are the project owner’s. The apportionment of the liability to give effect to the risk allocation has therefore been a matter of great controversy. Many delay analysis methodologies have been developed over the years for performing this task. This paper reports on an empirical study into the current practice in the use of these methodologies in the United Kingdom, as part of a wider study aimed at developing a framework for improving delay claims analysis. The part of the study reported here was based on a questionnaire survey of key informants. The issues investigated include the categories of staff within contracting organizations who contribute to delay claims analyses, the awareness, use and reliability of existing delay analysis methods and the obstacles to their use in practice. The main findings of the study are that: (1) the preparation of delay claims often requires input from commercial managers (quantity surveyors), schedulers, site managers, external claim consultants and estimators; (2) commercial managers have the greatest involvement; (3) claims analyzed using the as-built versus as-planned and the impacted as-planned techniques are often successful although there is considerable literature on the shortcomings of these techniques; and (4) the main obstacles to the use of the methods relates to deficiencies in project records and scheduling practice.     

Modified But-For Method for Delay Analysis

“But-for” is a widely used method for analyzing and apportioning project delays among the responsible parties. Despite its acceptability, the traditional but-for method suffers from serious drawbacks; namely its narrow focus on the point of view of a single party and its inability to accurately consider concurrent delays. In this technical note, several improvements have been made to the but-for method to produce repeatable results and to account for concurrent delays. Details of the modified but-for (MBF) method are provided along with an example to demonstrate its advantages. To automate the MBF method, it has been coded in a macro program on commercial project management software. The method is simple and can help practitioners in apportioning project delays in an accurate and equitable manner.     

Dynamic Memory Computation of Impedance Matrix Method

The computational efficiency of the impedance matrix method has been greatly improved for large pipe networks with various dimensions and complexity. Several numerical methods for solving linear system were modified to deal with the complex domain operation and used into impedance evaluation. Two different memory reduction schemes were developed based on one-dimensional storage and implemented with the biconjugate gradient method and the Gaussian elimination scheme, respectively. A new implementation of the impedance matrix method, namely, the dynamic memory allocation scheme, was introduced to efficiently model hydraulic transients in pipeline systems that have large topological structures. Three hypothetical pipe networks, the multiseries system, the multilooped system, and the multiblock system, were used to test the performance of the developed schemes. The impact of randomizing pipeline parameters, i.e., friction factor, length, and wave speed, on computation efficiency was evaluated and compared. The dynamic memory allocation scheme not only reduces costs substantially in CPU execution time and memory space compared to other schemes but also shows significant potential as a real-time unsteady flow predictor for large pipe networks.     

Delay Mitigation in the Malaysian Construction Industry

This paper describes the importance of applying proper management in dealing with delays in construction for a growing economy. The main objective of this paper is to identify the management tools that are practiced in the local construction industry in mitigating delay. It also aims to identify the main factors that lead to project delays and to suggest recommendations on how to overcome or mitigate effects of the problem. Data is gathered from responses from questionnaire survey and interviews with those involved in construction project. The surveys and research findings indicate that delay incidents occur mainly during the construction phase of a project and one or more parties usually contribute to delay. This paper highlights the importance of having more experienced and capable construction managers as well as skilled laborers to enable the industry to develop at a faster rate either nationally or internationally.     

Computerizing ICBF Method for Schedule Delay Analysis

Schedule delay is a common construction dispute. For analyzing schedule delays, a previous study had proposed an academic analysis method, the “isolated collapsed but-for” (ICBF) method. However, because many construction projects involve numerous complex activities, the procedure of using the ICBF method for schedule delay analysis is time-consuming. Therefore, this study used Microsoft Visual Basic for Applications (VBA) language and spreadsheet techniques to develop an Excel-based program for rapid delay analysis rather than manual calculation. A case study confirmed that the program automatically produces analytical results with only common delay documents (as-planned and as-built schedules and identified delay events). Compared with previous studies, schedule analysts can obtain analysis results quickly and correctly. Research results provide not only a convenient tool for schedule delay analysis but also a guide to computerize various academic delay analysis methods in the future.     

Method for Calculating Schedule Delay Considering Lost Productivity

A delay claim often occurs when a difference between the actual completion date and the contract completion date exists. The duration of a delay is an essential piece of information required for determining the cause of a delay. However, it is difficult to analyze a delay claim due to the fact that numerous factors that cause this delay, thereby making it a very complex issue. One of such factors is the lost productivity or loss of productivity. Despite the fact that it is one of the major causes of delay, there have been only a few studies that focus on converting lost productivity into delay duration carried out to date. Claims for productivity losses are generally the result of tension between the contractor and the owner. This tension arises due to the great difficulty involved in quantifying disruption effects. Thus, to calculate accurately the delay duration, a logical method for analyzing schedule delay caused by lost productivity is necessary. Therefore, in this study, we propose a method for analyzing construction schedule delay where this lost productivity is taken into consideration. This methodology was implemented on a case project to ascertain its practicability, and to decide whether it can be utilized in the case of a delay claim related to lost productivity. The significance of this paper is twofold. One is the method to convert the lost productivity into the delay duration, which can be applied to reasonable delay claim settlement. The other is the process to analyze the construction schedule delay considering lost productivity.     

用计算法修复车床大拖板

在修理车床拖板和床身导轨时,经常由于床身导轨棱形导轨和平导轨磨损不一样而采用的磨削深度一样,致使修理后车床拖板倾斜下沉。本文为此进行了专门讨论,提出了平导轨与棱形导轨补偿值之间的数学关系,并提出了两种解决方法:三点同轴计算法和啮合间隙计算法。     

Causes of Delay in Building Construction Projects in Egypt

Delay in construction projects is considered one of the most common problems causing a multitude of negative effects on the project and its participating parties. This paper aims to identify the main causes of delay in construction projects in Egypt from the point of view of contractors, consultants, and owners. A literature review was conducted to compile a list of delay causes that was purged based on appropriateness to Egypt in seven semistructured interviews. The resulting list of delay causes was subjected to a questionnaire survey for quantitative confirmation and identification of the most important causes of delay. The overall results indicated that the most important causes are: financing by contractor during construction, delays in contractor’s payment by owner, design changes by owner or his agent during construction, partial payments during construction, and nonutilization of professional construction/contractual management. The contractor and owner were found to have opposing views, mostly blaming one another for delays, while the consultant was seen as having a more intermediate view. Results’ analyses suggest that in order to significantly reduce delay a joint effort based on teamwork is required. Furthermore, causes of project delay were discussed based on the type and size of the project.     

液压油氧化的分析及延缓氧化的方法

阐述了液压油氧化的原因、危害、简易检测方法、控制措施及实际取得的效果。     

张力减径机工艺计算方法的研究

针对从西德引进的集体传动12架张力减径机未购买其工艺软件的问题,从工艺理论上建立了集体传动张力减径机的工艺计算方法,为新规格产品的开发找到了理论依据。     

基于Matlab的热加工图的数值构造方法

利用热加工图(Processing Map)可以分析材料在不同区域(不同的变形温度和应变速率)的高温变形机制,从而获得热加工"安全区"和"不安全区",达到控制组织演变、避免缺陷的产生和优化工艺参数的目的.Murty提出热加工图计算方法适用于复杂本构方程的材料,但其公式中含有积分项,计算过程复杂.Matlab具有强大的矩阵计算功能,本文给出了基于Matlab平台的计算过程和简易程序,可快捷得出计算结果.并绘制出材料的热加工图.     

Causes of Delay in the Planning and Design Phases for Construction Projects

Problems of delay occur in all phases of construction projects. While most previous studies have focused on finding causes or overcoming delays in the construction phase, few studies have analyzed delay problems in the planning and design phases. The main purpose of this study is to identify and rank delay causes in the planning and design phases. A structured questionnaire was sent to engineers at the A/E companies for public construction projects in Taiwan. Based on 95 valid responses, this study identified the delay causes and analyzed the importance and frequency of delays using the relative importance index. Analytical results reveal that “changes in client’s requirement” are the main causes of delays in both planning and design phases. The finding is good justification for many public clients who usually change their requirements during the planning and design phases that really delay construction projects.     

容忍延迟网络中基于生灭模型的消息控制方法

提出了在多拷贝传递的基础上增加消息拷贝消除机制,合理地控制了网络中的消息拷贝数.在网络中根据节点相遇时消息拷贝教发生变化的特性,构造了消息拷贝数的离散时间的马尔可夫链,建立生灭模型,进一步验证并得出了平稳分布.通过仿真实验比较,相遇次数与时间基本上是线性关系,与理论模型极为相近.与传染路由比较,采用拷贝消除机制网络中的消息拷贝数有了明显的减少,消息成功传递率达到90%,适当增加延迟时间,能够达到100%.消息拷贝数的平稳分布与仿真实验中基本一致.     

钢坯加热炉待轧决策方法及应用

介绍了钢坯加热炉优化待轧炉温决策的目标函数及求解方法,并提出了运用在实际控制系统中的一种优化待轧炉温解决方案.结果表明：模拟和实际运行效果良好.     

防静电环氧地面施工工艺

沈阳有色冶金机械总厂研究所理化实验室按工艺要求采用防静电环氧地面,该地面具有防静电,抗腐蚀作用.叙述了工艺原理,工艺流程,和施工要点,包括基层处理,底层、中层、面层的施工和养护在内的施工工序以及工程验收取得的主要技术指标和质量标准.     

Resource-Activity Critical-Path Method for Construction Planning

In this paper, a practical method is developed in an attempt to address the fundamental matters and limitations of existing methods for critical-path method (CPM) based resource scheduling, which are identified by reviewing the prior research in resource-constrained CPM scheduling and repetitive scheduling. The proposed method is called the resource-activity critical-path method (RACPM), in which (1) the dimension of resource in addition to activity and time is highlighted in project scheduling to seamlessly synchronize activity planning and resource planning; (2) the start/finish times and the floats are defined as resource-activity attributes based on the resource-technology combined precedence relationships; and (3) the “resource critical” issue that has long baffled the construction industry is clarified. The RACPM is applied to an example problem taken from the literature for illustrating the algorithm and comparing it with the existing method. A sample application of the proposed RACPM for planning a footbridge construction project is also given to demonstrate that practitioners can readily interpret and utilize a RACPM schedule by relating the RACPM to the classic CPM. The RACPM provides schedulers with a convenient vehicle for seamlessly integrating the technology/process perspective with the resource use perspective in construction planning. The effect on the project duration and activity floats of varied resource availability can be studied through running RACPM on different scenarios of resources. This potentially leads to an integrated scheduling and cost estimating process that will produce realistic schedules, estimates, and control budgets for construction.     

冷床设备基础工程大体积混凝土施工及温控计算

文章针对衡阳钢管厂二连轧冷床工程施工,根据现场环境、材料、结构形成等诸方面的条件,制定了可行的技术方案,并相应进行了温控计算,供工程技术人员在处理类似工程时参考.     

Finite Difference Method for Computation of 1D Pollutant Migration through Saturated Homogeneous Soil Media

The physical processes such as advection, dispersion, and diffusion and interaction between the solution and the soil solids such as sorption, biodegradation, and retention processes have been considered in the governing equation used in the present study. Finite difference method has been adopted herein to solve the one-dimensional contaminant transport model to predict the pollutant migration through soil in waste landfill. In the finite difference technique, the velocity field is first determined within a hydrologic system, and these velocities are then used to calculate the rate of contaminant migration by solving the governing equation. A total of seven contaminants have been chosen for analysis to represent a wide variety of wastes both organic and inorganic. A computer software CONTAMINATE has been developed for solution of the contaminant transport model. Results of this study have been compared with existing analytical solution for validation of the proposed solution technique. Design charts for liners have also been developed to facilitate the designers. The liner thickness has been optimized by considering the effect of velocity of advection, dispersion coefficient, and geochemical reactions for all the contaminants of this study.     

New Method for Construction of Diaphragm Walls

Diaphragm walls are built to exclude earth and water from an area so that work may be performed under reasonably dry conditions. The range of applications for diaphragm walls includes earth-retaining and load-bearing walls for a variety of constructs such as underpasses, deep basements, underground stations, tunnels docks, and pump houses. In traditional construction methods, the concrete diaphragm wall consists of separate panels, which are not formed as a continuous monolithic construction. Vertical joints are used to divide the wall into panels, and horizontal reinforcement is not continuous from one panel to the next. Recently, a diaphragm wall, believed to be one of the largest ever built, was successfully constructed in Egypt with a continuous horizontal reinforcement. This paper describes in detail a new construction method for a diaphragm wall system. In addition, the difficulties encountered during construction are highlighted. Movements of the wall during excavation are reported. A comparison between the new and traditional construction methods is carried out in terms of cost and schedule. Applying the method presented in this paper offers substantial opportunity for reducing the steel reinforcement requirement and eliminating the use of shoring systems or ground anchors.