Search query: defective work cost in construction

Related papers:

abstract: Abstract CdS, as semiconductor catalyst, has attracted much attention in photocatalytic production of hydrogen for the wide range utilization of visible light. Usually, noble metal deposited as a co catalyst on CdS surface is required to achieve high photocatalytic activity. Thus, replacing noble metal via cheap and easy synthesis co catalyst would be of great value for developing cost effective photocatalyst. In this work, noble metal free defective Mo15S19 combined with CdS diethylenetriamine (DETA) hybrid makes efficient separation of photoinduced carriers, and more importantly, reduced overpotential for hydrogen evolution reaction, thereby improved catalytic hydrogen evolution performance of designed composite. In particular, 3%Mo15S19/CdS DETA systems exhibited a high rate of hydrogen production, reaching 3.61 mmol g 1 h 1, which is similar with 3%Pt/CdS DETA and 9.5 and 2.19 times as high as that of CdS nanoparticles (NPs) and CdS DETA, respectively. At the same time, photocorrosion resistance of 3%Mo15S19/CdS DETA systems was dramatically improved. According to DFT theoretical calculations, it was found that the enhanced photocatalytic performance and anticorrosion are mainly due to efficient transfer of photoexcited electrons from CdS DETA to Mo15S19.
author_names: Zhen Li

Yang Yang

Kai Dai

Jinfeng Zhang

Luhua Lu
title: Construction of defective Mo15S19/CdS diethylenetriamine heterosctructure photocatalyst for highly active and stable noble metal free photocatalytic hydrogen production
venue: Applied Surface Science
year: 2019

abstract: Construction industry is of critical significance to the development of Australia regarding economic and social aspect, contributing one of the largest portions to Australia's GDP and providing residential building, infrastructure and functional facilities to the operation of the cities as well as job opportunities to the country. Construction disputes are common trait of this industry causing detrimental consequences to the construction projects leading to financial loss and delays in construction projects. Although there is a considerable amount of research and knowledge contributing to the study of dispute causation, legal disputes remain prevailing and hinder the process of construction, especially from the cost perspective. In order to improve our understanding of the causation factors underlying the legal disputes this research was conducted by examining the details of recent legal cases in NSW. Our objective was to determine the extent of the impact of insufficient work front instruction including missing specifications on occurrence of defective construction work. As a result, this research discusses that poor workmanship as a major causation factor is a direct derivative of vague job description. The observation that patent defects readily identifiable by inspection were a common source of dispute supports our hypothesis that ambiguity of the task provides tradespersons the opportunity to deliver a sub standard job. Professional ethics and technical skills of the tradies have been discussed to have a moderating effect. Clear and precise specifications are inevitable if disputes are to be reduced.
author_names: Zhaorong Wu

Payam Rahnamayie Zekavat

Sungkon Moon

Liyaning Tang

Sherif Mostafa
title: Investigating the root cause of legal disputes over defective construction
year: 2019

abstract: Purpose: Poor project knowledge and inadequate experience are frequently linked to construction time cost overruns. This paper aims to expound on the criticality of project knowledge and experience in the successful delivery of projects in the construction industry. Design/methodology/approach: Following a detailed literature review, a quantitative positivist approach with a questionnaire survey involving industry professionals is used to appraise the 30 prevalent causes of time cost overruns according to frequency, effectiveness and importance indices. The data are then subjected to Spearman's rank correlation tests and exploratory factor analysis. Findings: Using the importance index, which assimilates both frequency and effectiveness indices, the criticality of knowledge and experience in the overall context is seen as fundamental for addressing the contractor's faulty planning and scheduling, construction mistakes and defective work, site management and supervision, delayed/slow decision making, incomplete drawings and design documents and change/variation orders. Spearman's rank correlation tests indicate a good consensus of perceptions among the key parties involved. Next, an exploratory factor analysis uncovers six underlying knowledge based factors affecting construction performance, relating to inaccurate resource estimates, design changes, resource shortages, lack of experience, incompetence and mistakes and defects. Originality/value: The study draws out the repercussions of the hitherto limited research into the deficiencies in knowledge and experience in undertaking construction projects to enhance performance using knowledge management functions.
author_names: Jeffrey B H Yap

Ban Leong Lim

Martin Skitmore

Jason Gray
title: Criticality of project knowledge and experience in the delivery of construction projects
year: 2021

abstract: Abstract Since the end of the twentieth century, discussion on dwelling rehabilitation versus its demolition and new construction has been steadily increasing in intensity, which is especially due to the necessity for the regeneration of urban centres. However, rehabilitation is not always considered the most economical solution, and demolition and new construction may constitute a better option. In the present work, a multi family building in Seville, Spain, is used as a case study. After having suffered damage from a construction failure, it is assessed for its complete rehabilitation. Defective maintenance has worsened the bad condition of the building. A model is proposed, from the project budget perspective, that allows the environmental (Ecological Footprint indicator) and the economic (project's bill of quantities) assessment of the recovery of the dwelling. In the case study, the rehabilitation Ecological Footprint and the project cost are 0.06 gha/m 2 of floor area (457.22 EUR/m 2 and 0.14 gha/m 2 (576.33 EUR/m 2 for a new building on the same plot, respectively. It can be deduced that, even with a severely damaged building, the repair and retrofit work incurs a lower economic and environmental impact than that of the total replacement with a new construction.
author_names: Ma Desiree Alba-Rodriguez

A Martinez-Rocamora

Patricia Gonzalez-Vallejo

Antonio Ferreira-Sanchez

Madelyn Marrero
title: Building rehabilitation versus demolition and new construction: Economic and environmental assessment
year: 2017

abstract: In this short paper, we compare well known rule/tree classifiers in software defect prediction with the CTC decision tree classifier designed to deal with class imbalanced. It is well known that most software defect prediction datasets are highly imbalance (non defective instances outnumber defective ones) In this work, we focused only on tree/rule classifiers as these are capable of explaining the decision, i.e. describing the metrics and thresholds that make a module error prone. Furthermore, rules/decision trees provide the advantage that they are easily understood and applied by project managers and quality assurance personnel. The CTC algorithm was designed to cope with class imbalance and noisy datasets instead of using preprocessing techniques (oversampling or undersampling) ensembles or cost weights of misclassification. The experimental work was carried out using the NASA datasets and results showed that induced CTC decision trees performed better or similar to the rest of the rule/tree classifiers.
author_names: Igor Ibarguren

Jesus M Perez

Javier Muguerza

Daniel Rodriguez

Rachel Harrison
title: The Consolidated Tree Construction algorithm in imbalanced defect prediction datasets
venue: 2017 IEEE Congress on Evolutionary Computation (CEC)
year: 2017

abstract: The residential construction industry is an important contributor to the Australian economy; the industry employs a very large component of the national workforce, and yet the industry is plagued by defective work and poor quality. Previous research has revealed that defects and rework are endemic in the residential sector. In an attempt to quantify the degree of defects being experienced in new residential construction this paper provides an analysis of defects that were recorded by a government owned housing insurance organization, the Housing Guarantee Fund. This research represents one of the most comprehensive research studies of building defects undertaken to date in Australia. The data used were not based on a sample like previous studies but instead represent all new houses constructed in Victoria, Australia between 1982 and 1997. An analysis of the data revealed that one house in eight reported defects, and that the cost of rectification was 4% of the construction contract value. The paper discusses the nature of the most important defects and investigates the impact of contractor type and building type.
author_names: Anthony Mills

Peter E D Love

Patricia J Williams
title: Defect Costs in Residential Construction
year: 2009

abstract: Concrete is most utilized construction materials, it is having many advantages, some are low cost, long service life (when properly mixed, placed and cured) ease of construction and high compressive strength. In present time the civilization depends upon the available ranges of concrete or reinforced concrete (RC) structures, ranging from domestic structures to heavy structures. However, numerous concrete structures suffer important degradations and damages due to environmental exposure or extraordinary overload or have insufficient strength because of defective construction, increased service load requirements, or updated codes, fiber reinforced polymer (FRP) composites strengthening becoming nowadays a commonly accepted and widespread technique. The research includes static analysis of beam under glass fiber composite plate with PCC and RCC to optimize material and cost of beam with designed strength. In present research work the response of plain concrete beam, reinforced concrete beam and reinforced concrete beam with GFRP plate is analysed with finite element analysis sotware. ABAQUS software is used to perform analysis of beam. The results and outcomes of analysis concluded that the reinforced concrete beam with GFRP plate gives better results than any other case taken under consideration.
author_names: P K Joshi

Komal Bedi
title: Static Finite Element Analysis of Gfrc Simply Supported Beam
year: 2019

abstract: The techniques of strengthening reinforced concrete beams have been widely used in civil engineering. RC beams often need strengthening due to defective construction, having higher loads than those foreseen in the initial design of the structure, or as a result of material deterioration or accidental damage. The need for strengthening concrete structures has become a crucial problem all over the world. Rehabilitation of structures results in less construction waste materials, reserve natural resources, reduces the negative effects of the environment, saves time and cost, etc. The structural behavior of reinforced concrete beams strengthened by addition of steel plates or steel angles has been investigated in the undertaken research. The main aim of this research is to demonstrate the best method of the investigated strengthening techniques. The experimental work comprised of 18 RC beams divided into three groups; the first group consists of 6 normal RC beams, the second group contains 6 RC beams strengthened by addition of steel plates and the third group contains 6 RC beams strengthened by addition of steel angles. Keywords: Steel Plate, Steel Angle, RC Beam, Concrete
author_names: Ali I Tayeh

Sari W Abusharar
title: A Comparative Study on the Strengthening of RC Beams with Steel Plates and Steel Angles
year: 2018

abstract: In the last decades, developing and sustaining large complex engineering systems have become more challenging (de Graaf, Voordijk, van den Heuvel, 2016) To facilitate contracting firms in the Dutch construction industry in their ability to deliver these more complex projects, innovative procurement methods based on integrated contracts, using Uniform Administrative Conditions for Integrated Contracts (UAV ic) such as Design Build or Design Build Maintain, are used by large clients in the Dutch construction Industry (de Graaf, Vormer, Boes, 2017; Makkinga, de Graaf, Voordijk, 2018) The transfer of responsibility from clients to contracting firms for the project design creates the demand for contracting firms to control and review the quality of their own work. Design decisions and commitments have a great impact on project life cycle cost and defective design is a major cause of contract claims and change orders during construction (Andi Minato, 2003) de Graaf et al. (2016) and de Graaf, Vormer, et al. (2017) argue for a transition to the SE way of working in the Dutch construction industry. Reef Infra, a mid sized Dutch contracting firm, finds it challenging to increase standardization, independency, and overall performance regarding their SE process and finds it also challenging to collect performance information to SE related tasks. SE is a relative new way of working, which leads to a lot of insecurity (within the organization) struggle and discussion between Reef Infra and their clients and between Reef Infra and their subcontractors. Reef Infra is looking for opportunities to measure their SE performance to find or identify opportunities for improvement. Measuring their SE performance enables them to target underperforming SE tasks. Alongside their wish to improve their SE application, Reef Infra also finds it challenging to collect performance information, specifically regarding SE tasks and how to relate this to common project success categories in terms of budget, schedule and quality. When they are able to quantify this relation, Reef Infra can prove that their control over the SE process contributes to common project success categories and that they can use that information for BVP tenders. To identify solutions for these challenges a research project is conducted. The project is performed to answer the following research question: How can a Civil Engineering Contracting Firm measure their Systems Engineering performance and how do these metrics relate to project success indicators budget, schedule and quality? In this research project, a measurement tool is developed and applied to measure SE performance and project success in terms of budget, schedule and quality. The goal of the research is to assist Reef Infra in their improvement of their SE process by measuring their SE application in projects under UAC ic. In addition, how SE contributes to achieving project success indicators budget, schedule and quality, which are commonly used as BVP objectives, is also explored. The goal within the research is to advice Reef Infra how they can measure their SE application to improve their SE process and to relate the extent of SE application to project success indicators budget, schedule and quality. A case study research design is applied to develop and apply the measurement tool. Multiple cases were selected according to the one phase screening approach of Yin (2014) There were two main sources of evidence to fill the measurement tool. First, an extensive document analysis was performed to provide initial results. Afterwards, unstructured interviews were conducted to fill gaps in the results and validate findings. A case study protocol was developed to ensure that within case results are mutually comparable in the cross case analysis. Based on the results of the research, the relation between the extent of SE application and project success cannot be determined. Too little data points were gathered. Looking at the graphs (Figure 8, Figure 9 and Figure 10) there is no optimum in the extent of SE application in relation to project performance. It is unclear if a higher or lower extent of SE application could prevent such events from happening. The findings of Honour (2013) and Beasley and O'Neil (2016) cannot be confirmed, because no clear relation cannot be established. Moreover, in the cases many other characteristics or events seem to affect the project success. To eliminate bias of such characteristics on the relation between the extent of SE application and project success, more assessments of projects using the measurement tool have to be conducted. The results do however confirm that the extent of SE application is different in each project. Although, all projects score an average SE score within a range of approximately 10% because the maximum score was 66% and the lowest score was 56% The results suggest that SE elements are in some projects not applied while in other projects the same SE elements were applied quite substantially. This means Reef Infra does not apply a comprehensive and standardized SE method in their civil engineering projects. There are multiple reasons for the extent of SE application. First, unclear and out of date SE procedures affect the extent of SE application. Second, the level of SE skill and knowledge affected the extent of SE application. Third, Reef Infra is highly dependent on the client for the extent of SE application. Establishing clear SE procedures, enhancing SE skill and knowledge and reducing client dependency could enable the contractor to properly assess the extent of SE necessary to realize project success. A contingency approach to SE in construction projects can prevent over and underinvestment. Relating SE performance to project success, enables proper recognition of how much SE activity is enough. This aspect must be further explored to establish clear methods for recognition. The approach to SE must be corresponding with the characteristics of the project, otherwise SE does not provide value in the project. Although, the measurement tool developed in the research emphasizes the extent of SE process applied at the project level it does provide the contracting firm with the necessary information to target underperforming SE tasks. Overall, to ensure that the contractor is capable of approach SE as a flexible process and not to overemphasize on SE tools, it is important the contractor must establish clear SE procedures, enhance SE skill and knowledge and reduce client dependency. To conclude, based on the qualitative case study research findings, the SE process framework is applicable to assess the extent of SE application at a civil engineering contracting firm. The output of the measurement tool provide contractors with vital information to improve their SE process. Moreover, three specific factors affecting the extent of SE application are derived from the results. Based on the results no clear relation could be established between the extent of SE application and project success in terms of budget, schedule and quality. However, the findings do suggest when more projects are assessed using the measurement tool a relation can be established and the bias effect of other characteristics and events that also affect project success can be eliminated. Therefore, Reef Infra benefits from further applying the measurement tool to assess the extent of SE application in their projects.
author_names: Ebel Berghuis
title: Measuring systems engineering and project success an evaluation of systems engineering practices and project duccess in a Dutch civil engineering contracting firm
year: 2018

abstract: In promoting the new rural cooperative medical system in our country,we face a series of problems such as,low participation; defective management system; high cost in collecting fund,unreasonable compensation standard,limited compensation ability; difficulty in supervision; defects in legislation and policy; lack of reasonable human resource system,and so forth. For the future,we need to normalize and improve it from the following aspects:strengthening the construction of managerial institutions and improving the management abilities; expanding channels for collecting fund,establishing long term effectiveness mechanism; improving the relation with the outside and forming positive interaction; establishing the rural urban integrated medical security system and management system as soon as possible; enhancing the medical supervision and improving the management efficiency; accelerating the work of legislation,ensuring the stability of policies on the new rural medical security system; reinforcing the human resource construction,emphasizing the cultivation of professionals for hospitals in townships,etc.
author_names: Chen Liu-qin
title: The New Rural Cooperative Medical System of Our Country:Characteristics,Problems and Countermeasures
year: 2009