Construction Defects Research Articles

Numerical modeling for evaluation of the thermal resistance of reflective airspaces with and without defects

The thermal resistances (R-values) of airspaces depends on the emittance of all surfaces around an airspace, dimensions, heat-flow direction, and the temperatures of the bounding surfaces. Assessing the energy performance of building envelope components and fenestration systems requires accurate results for the R-values of any enclosed spaces. The evaluation of reflective insulation R-values has evolved to include use of computational fluid dynamics and surface-to-surface radiation to quantify convective and radiative contributions to the heat transfer across airspaces of all types. This paper compares an advanced and validated model for calculating enclosed airspace R-values with the widely-used ISO 6946 and airspace R-values in the ASHRAE Handbook-Fundamentals. The impact of construction and installation defects on the thermal performance of reflective insulation has not been previously evaluated. In this research, an advanced model was used to evaluate a construction defect and dimensional aspect ratios that one-dimensional methods do not address. Imperfect installation and defects that result in air movement into or through a reflective insulation assembly reduces the thermal resistance of the assembly. Additionally, the amount of thermal resistance reduction depends on the amount and temperature of invasive air or the size of internal defects that allows natural convection inside the reflective airspace. In this study, these performance issues are evaluated quantitatively using computer simulation techniques. The differences in results obtained using methods that are currently being used to evaluate the R-value and the advantages of the advanced method for evaluating the reflective insulation performance for different applications are discussed. For the case considered in this study, the results showed that the failure to achieve parallel surfaces results in less than a 5% decrease in thermal resistance. Also, the results showed that internal air gaps between airspaces result in negligible loss in R-value unless air gaps that allow circulation between airspaces are created.

Key residential construction defects: a framework for their identification and correlated causes

Purpose Construction defects are one of the primary causes of deficient quality performance and constantly yield project cost and schedule overruns mostly because of rework. This study aims to propose a new method for identifying a bespoke checklist of the most recurrent defects in residential construction work and their correlated causes as a basis for developing a framework for practical improvements in managing defect risks. Design/methodology/approach A literature review was first used to ground the defects within the existing theory and develop a new framework for ranking the key defects involved. This was demonstrated and tested by an analysis of Queensland Building Construction Commission (QBCC) archival data for 42,000 reported defects in new Queensland residential buildings. A questionnaire survey of 427 construction practitioners from 37 trades was then conducted to determine their causes. Findings The developed framework consists of preconditions for defective acts, defective supervision and organizational influences and is found to be suitable for analyzing the QBCC archives to rank the 20 most frequent defects. In the demonstration study, a questionnaire survey identified the highest frequency latent causes of defective acts to be workers taking shortcuts to complete tasks, workers’ lack of skill or knowledge level, challenges and limitations of technical constructability, and incorrect material supply; the failure to correct a known problem and poor supervision for defective supervision; and inadequate employee training, low managerial priority for quality and high time pressure and constraints for organizational influences. Originality/value The method is a new approach to identifying the key defects in residential construction work and their correlated causes for developing bespoke checklists as an aid to in managing defect risks.

The strong influence of small construction errors on sound insulation of buildings with heavyweight concrete structure: A Portuguese case study

In order to attain an expected sound insulation in buildings, it is necessary to employ appropriated constructive solutions, but it is also fundamental to guarantee compatibility with other involved design professional fields, proper detailing of solutions and correct on site mounting. A solution with a predicted high acoustic performance may result in failure if there is no proper interconnection between other design professional areas or if execution mistakes occur, even if of very small dimension. The main objective of this technical paper is to analyse the influence of defects that typically occur in buildings, located in Portugal, resulting in very poor airborne or impact sound insulation performance. The chosen situations refer to buildings with heavyweight concrete structure, where small construction defects occurred and/or wrong decisions were taken, ending up with a large reduction on the final acoustic performance. Some of these errors, given their small size or because they occurred in hidden zones, easily passed unnoticed, on site. The defects here addressed in what refers to airborne sound insulation are related with execution of double masonry hollow brick walls, sound bridges in acoustic suspended ceilings, passage of ventilation or sewage pipes, inappropriate installation of acoustic doors, shutter boxes or windows. As for impact sound insulation, the presence of rigid connections is the main focus of the characterisation here performed.

Analytical study on influence of subsurface voids on moment capacity of singly reinforced concrete beam – Inspired by a project case study

Ultrasonic echo tomography is a non-destructive testing technique that has been used to detect subsurface construction defects located within reinforced concrete members. In order to reasonably define the scope of the repair work for the detected subsurface construction defects, it is important to understand the relationship between the extent of the construction defects and the performance of structural members. This preliminary analytical study was conducted to evaluate the moment capacity of singly reinforced concrete beam sections containing subsurface voids. It was determined in this study that if the location of void remained the same, an increase in the depth of void resulted in a reduction in the moment capacity. As the void extended outside the compression zone and the depth of void continued to increase, the moment capacity did not decrease further. If the depth of void remained the same, a void located closer to the top of beam resulted in more reduction in the moment capacity than the same void located closer to the neutral axis. A parameter named the percentage of remaining moment capacity was proposed to be used to identify the unacceptable void configurations from the standpoint of moment capacity.

Attesting Building Defect Causality Factors of The Actual Project Data and Internet Survey: A Triangulation Method on Empirical Data Statistical Analysis

The paper aims to analyse the findings of the building or the construction defects found from the mix-method research through the triangulation technique to maximise its results consistencies. Early on, the methodology approach for the study involved the mix-method option involving the collection of the actual projects’ defect data and the structured online questionnaires survey. In this paper, a triangulation method was used to increase the credibility and validity of research findings. The findings revealed a strong correlation between actual defect variables empirical input and the descriptive statistical defect census. The results also show the Likert Scale’s Google Form (LS GF) responses on the actual defects independent and dependent variables versus statistical defect census survey; tabulates on decisive co-relation causation factor between the multiple defect categories. The paper describes, identifies, and proved the critical aspect of building defects contribution factors from actual defects data collection and online census's statistical input.

A Study of Prospective Barriers, Benefits and Measures for Building Information Modeling (BIM) Adoption in Nepalese AEC Industry

The construction industry needs modern construction methodology and technology to improve sustainability and production performance. Building Information Modelling (BIM) technology supports improving the quality of products by reducing design and construction defects, risks to the health and safety of workers, and reduce overall project cost and delivery time. The BIM has capabilities, but it is still undiscovered and unable to exploit the full scale of its benefits in the Architectural Engineering and Construction (AEC) industry. There is a trend to adopt the BIM level 1, which is limited to 2D and only in a few cases 3D models uses in the design and construction of residential and commercial buildings, particularly in Nepal. Hence, this paper focuses on providing insight into the BIM benefits and identifies the potential barriers while adopting BIM Level 3 in Nepal. This was accomplished by developing a 4DBIM model of a multi-story residential building in Nepal and conducting the industry survey via focus group with the AEC professionals based on the developed 4DBIM model. A comprehensive literature review was conducted and presented the findings of the BIM benefits and barriers while adopting BIM. The study found that commercial and governmental projects can immediately be adopted BIM technology. It is concluded that the unavailability of skilled BIM users and the lack of proper policies for BIM adoption are key barriers in Nepal. Hence, the new policy is required to achieve and exploit the full scale of the BIM benefits and improve the project delivery in terms of quality, cost and time including the health and safety of workers and the sustainability of the AEC industry.

Assessment of public building defects and maintenance practices: Cases in Mettu town, Ethiopia

Building flaws are one of the main aspects of building problems that need to be carefully considered. Besides the high demand for construction projects in Ethiopia, the problems of defective buildings and maintenance issues were so prevalent. According to the researchers' field survey, Mettu town's public buildings have suffered from major building defects and deterioration, and neglect of maintenance practices. This research aimed to assess building construction defects and maintenance practices in Mettu building projects. A case study and questionnaire survey were utilized for data collection. A Case study was conducted on a randomly selected nine public building projects in Mettu Town using site observation and formal checklists. Whereas, a questionnaire method was used to address the study objectives based on respondents' perspectives using ordinal scales of Likert's. The Spearman rank correlation coefficient, mean score, and weighted average values were utilized for data analysis using Microsoft Excel spreadsheet and SPSS version 20 tools. The study revealed that non-structural cracks were found the top first-ranked building defect. Shortage of budget, inadequate maintenance standards, and Poor maintenance cultures were the top-ranked building maintenance factors. Project delay, High maintenance cost, and diminishing reputation were the top-ranked impacts of building defects. Periodic and regular construction supervision and proper and periodic maintenance were the top measures to minimize building defects.

Investigating the influence of quality management on building thermal performance

PurposeDespite the number of quality management procedures being currently applied, construction defects in the domestic sector are acknowledged to contribute to the energy performance gap of buildings. This paper investigates the limitations and challenges to the implementation of project quality plans (PQPs) and their impact on the achievement of expected thermal performance in the UK social housing projects.Design/methodology/approachA qualitative approach, guided by grounded theory, was used in this research. This methodology provided the structure for systematic data analysis iterations, enabling cross-case analysis. An analytic induction process was designed to seek the explanation of the targeted phenomenon and required data collection until no new ideas and concepts emerged from the research iterations. This study collected data from five social housing projects through interviews, site observations and project documentation.FindingsMultiple limitations and challenges were identified in the implementation of PQP to deliver thermal efficient social housing. Generally, there is the need for more objective quality compliance procedures based on required evidence. When investigating the root of the challenges, it was concluded that the adoption of statutory approval as the main quality compliance procedure led to the dilution of the responsibility for prevention and appraisal of defects that compromised the effectiveness of PQP devised by housing associations (HA) and contractors.Originality/valueThis study identifies the shortcomings of PQP in addressing quality issues with potential to undermine the thermal performance of social housing projects. The findings could be used by HA, contractors and policymakers as steppingstones to improve the energy efficiency in the domestic sector.

Urban Drainage: The Challenges and Failure Assessment Using AHP, Addis Ababa, Ethiopia

Urban drainage infrastructures are facing critical challenges due to a lack of integrated asset management, periodic maintenance, improper design, and construction methodologies. The objective of this study is to understand the urban drainage challenges and assess the failure causes and their impacts to recommend possible mitigation measures. Drainage failure causes and impacts are analyzed using the analytical hierarchy process (AHP) qualitative multicriteria decision model after conducting technical group discussions, interviews, and technical field surveys. The assessment was performed by taking representative samples from both cross- and longitudinal drainage infrastructures. The AHP analysis results showed that approximately 35.5% and 28.6% of failure causes are debris and various solid wastes for cross- and longitudinal drainage structures with correlation coefficients of 0.93 and 0.95, respectively. The result showed that design and construction defects are the second major failure causes. The research results showed that urbanization has a direct relationship with major drainage failure causes, resulting from man-made debris and solid waste clogging. On the other hand, drainage failure caused by siltation, drifts, and vegetation is higher in newly developing semi-urban and agricultural areas. The number of barrels in cross-drainage structures also contribute significantly to cross-drainage failure by creating a flow barrier due to the intermediate columns. The drainage failure impact assessment result showed that both cross- and longitudinal drainage failures primarily impact road pavement following transport disruption and traffic accidents, accounting for 38.5%, 18%, and 16%, respectively. Our research recommended that the mitigation measures for drainage failure are proper asset management and maintenance, appropriate construction supervision, and awareness creation, with weights of 36.3%, 15.5%, and 15.3%, respectively. As a drainage problem mitigation measure, the longitudinal drainage analysis results showed that the provision of a combination of cross-fall slopes, gutter slopes, and local depressions at the inlets can contribute to an increase in the trapping efficiency of the drainage system by 50%, which can reduce surface flooding substantially.

Identification of construction defects in residential buildings

The formation of construction defects is a problem thatoccurs in every investment process. The aim of the research presentedin the article is to identify defects in residential buildingshanded over for use and to assess their degree of significance.To assess the significance of defects, the Pareto-Lorenz analysisand the called ABC classification. Based on the research, it wasfound that the defects identified in the following building elementsare significant for the quality of the building: plasters, windows,floors, electrical installations, common parts, plumbing,improper cleaning of elements, doors and glass

Energy transfer and patterning characteristics in pulsed-laser subtractive manufacturing of single layer of MoS2

The single-layer Molybdenum disulfide (MoS2) was subtracted by using pulsed lasers with different parameters. The machining results were tested by optical microscopy, Raman spectrum, photoluminescent (PL) spectrum, scanning electron microscopy (SEM), and atomic force microscopy (AFM), indicating that the femtosecond laser machining has a better boundary effect than the nanosecond laser. Molecular dynamics (MD) were used to simulate the subtractive manufacturing effect and thermal transfer under different pulse widths and energy conditions. It has been proved that the short-width pulsed laser is more suitable for patterning MoS2. During the MD simulation, wrinkles and defects were found during the laser machining of long-width pulsed laser. The band structure of MoS2 was calculated by density functional theory (DFT) to investigate the effect of different wrinkle and defect conditions on the nonlinear laser absorption. The effect of defects on MoS2 thermal transfer was explored by plasma construction defects. The energy transfer during long-width pulsed laser machining was obtained. This work provides fundamental understanding of laser patterning and machining of MoS2 for future device applications.

Behavior of Confined Headed Bar Connection for Precast Reinforced Concrete Member Assembly

The mechanical performance of precast RC structures relies on the connections, especially the connections of steel bars, between precast RC members. Grouted sleeve splices and grouted spiral-confined overlap connections are widely used in engineering practice in China. Both of these two connection splices require on-site grouting. The process is concealed and invisible, leading to difficult on-site inspection. The unseen defects cause a challenge for detection and repair, which may impair the reliability of precast RC members’ behavior. This paper presents an RC member assembly connection with visible on-site construction quality-monitoring. The proposed confined headed-bar connection (CHBC) consists of two overlapping headed bars and confinement stirrup. With CHBC, the potential construction defects are diminished, and subsequently the construction quality as well as the reliability is upgraded. Experimental investigation on 18 CHBC specimens was carried out; the main parameters considered were overlap length and bar-head size. The failure modes, bearing capacity, stirrup strain development and bond versus slip response are studied. Working mechanism of CHBC is investigated in terms of bond behavior force and concrete compression force at head experimentally and numerically; distributive relationship of these two forces is revealed. The results show that for Φ12 reinforcement, a 90 mm overlap length under test parameters is adequate to reach headed bar ultimate strength in CHBC. Finally, a CHBC-bearing capacity prediction method is suggested based on the superposition method and strut-and-tie model theory.

Experimental and Numerical Study on Unreinforced Brick Masonry Walls Retrofitted with Sprayed Mortar under Uniaxial Compression

The use of shotcrete or sprayed mortar is a common construction alternative to retrofit unreinforced brick masonry (URM), and extensive research has already been carried out in this area. However, most studies have been conducted on lateral strength, for example, eccentric compression or seismic forces. On the other hand, there are few studies about uniaxial compression, and the results of most studies confirm a strong relationship between the thickness of the retrofitting layer and whether it is a double-sided retrofitting section. However, most studies are exclusively experimental, with few samples, and lack numerical analysis; therefore, deeper research is required on this issue. In this sense, this paper combined experiments and finite element (FE) simulations to further study the uniaxial compression. A series of cyclic uniaxial compression experiments on URM retrofitting with sprayed mortar were performed. The experimental results were used to calibrate the FE model. Using these calibrated FE models, more variable parameters were run so that more reference results could be obtained. Moreover, the resulting damageable model of FE will be useful for studying the behavior in the inelastic phase. Results found that the compression strength of most composite walls retrofitted with sprayed mortar increases with the thickness of the sprayed layer and can improve the construction defects of the masonry itself. An over-thin sprayed layer reduces the range of the elastic phase of the composite wall. This phenomenon tends to stabilize with increasing thickness. The ultimate strength of the composite masonry is generally positively correlated with the overall increase in the thickness of the sprayed mortar but may cause a negative contribution to the ultimate strength of the composite masonry when the sprayed layer is too thin. The contribution of double-sided spraying to the ultimate strength of the composite wall was not as large as expected, but the contribution to the improvement of the elastic modulus of the wall was significant.

Recent advances in metal-organic framework/carbon nanotube nanocomposites for developing analytical applications.

Nanoscience shows promise for scientific advancement in many sectors, such as biology, energy, materials, environment, and manufacturing. Nanocomposites are mixtures of two or more materials, one of which is nanosized particles. The composites are expected to show combined features resulting in general enhancements in their physical and chemical properties. Metal-organic frameworks (MOFs) are coordination polymers that have attracted attention from researchers in recent years due to their porosity and controllable functionality. Another example of interesting nanomaterials is carbon nanotubes (CNTs) which are also known for their mechanical and thermal properties. Incorporation of both these materials into a nanocomposite has shown an enhancement in properties and conquered challenges in the defects of construction. This mini-review sheds light on the recent synthetic approaches and characterization of MOF-CNT nanocomposites in order to access porous selective nanocomposites that can improve analyte detection in environmental matrixes and biological systems. A summary of the chemical composition of nanocomposites, analytes in the target, and analytical techniques used is provided.

Enhancing building maintainability through early supplier involvement in the design process

Abstract The post-construction phase represents a critical milestone in the project lifecycle. This is because design errors and omissions as well as construction defects are examined during this phase. The traditional procurement approaches that are commonly adopted in construction projects separate design from construction, which inhibits contractors, suppliers and other parties from providing the design team with constructive comments and feedback to improve the project design. Consequently, lack of considering maintainability aspects during the design process results in increasing maintenance and operation costs as well as reducing building performance. This research aims to investigate the role of early supplier involvement (ESI) in the design process as an approach for enhancing building maintainability. To achieve this aim, a research methodology consisted of literature review, case studies and survey questionnaire was designed to accomplish four objectives. Firstly, literature review was used to examine the concepts of building maintenance, maintainability, the design process and ESI. Secondly, three case studies were presented and analysed to investigate the role of ESI towards enhancing building maintainability during the design process. Thirdly, a survey questionnaire was conducted with a representative sample of architectural design firms (ADFs) in Egypt to investigate their perception and application of ESI towards enhancing building maintainability during the design process. Finally, the research developed a framework to facilitate ESI during the design process in ADFs in Egypt. Data analysis showed that ‘Difficulty of trusting external parties and sharing information with transparency’ was ranked the highest challenge of ESI in ADFs in Egypt.

Research of the causes of defects in the basic construction of a grain wagon after longterm operation

Research of the causes of defects in the basic construction of a grain wagon after longterm operation

Methodological importance of legal constructions and their influence on the legal norms interpretation

The article reveals the methodological significance of legal constructions and shows their influence on the interpretation of legal norms. It has been found that legal construction is one of the epistemological tools of legal science and means of interpreting legal norms in the process of their implementation. A concentrated expression of the possible conditions of law enforcement determines the methodological significance of legal constructions during the interpretation of legal norms. The legal construction is shown as a set of stable connections of the object, which ensure its integrity and identity. Emphasis is placed on the fact that intraindustry and inter-industry connections of legal norms allow law to preserve its properties as a regulatory in the face of internal and external changes, to be stable and stable. The existence of a stable structure determines the existence of law as a system is a condition for the existence of law. The author came to the conclusion that in order to optimize legal interpretation activity, it is necessary to improve the process of eliminating defects in legal constructions. The ambiguity and inconsistency of legal constructions is a consequence of the increase in the number of scientific terms, special expressions, contradictions and gaps in the normative material. The reason for this is hasty normative design without compliance with the requirements of legal technique. With the help of legal constructions, insightful, detailed and in-depth clarification of the content of legal norms is carried out.

Concrete Structure Ultrasonic Testing Technology Research Latest Progress and Development Trend

Many concrete structures in use have safety problems due to material deterioration, actual construction defects, structural damage, etc. Therefore, nondestructive testing is required to determine the presence of defects. Ultrasonic technology is an important tool in nondestructive testing, which can detect defects in concrete and be combined with other methods or models to make it more accurate. At present, ultrasonic inspection technology has been more research at home and abroad, both in theory and in engineering, and there has been great progress. This paper summarizes the latest progress of ultrasonic inspection technology for concrete structures at home and abroad respectively, and points out the future development trend.

Evaluation of common defects of grouted sleeve connectors

Grouted sleeve connectors have been widely used in vertical connections of prefabricated reinforced concrete structures. However, the quality of grouted sleeve connections are likely affected by adverse factors during winter construction such as grouting operation error, adverse environmental change, and management negligence. Some defects in winter construction are difficult to check including insufficient strength of grouting material, insufficient anchorage length of connecting reinforcement bars and adverse impact of low-temperature grouting. Although research has been carried out on the connection performance of grouted sleeves with defects, few are on the comprehensive evaluation of the connection performance of grouted sleeves with different defects caused in winter construction. In this paper, 25 groups (75 sleeves) of semi-grouted sleeve connectors with various defects are designed and manufactured. The effects of insufficient anchorage (i.e. insufficient length of reinforcement bar extending into the sleeve), insufficient strength of grouting materials and low-temperature grouting on the tensile properties of semi-grouted sleeve connectors are experimentally studied. On the basis of the test, finite element analysis is performed on extended defect conditions to comprehensively evaluate the safety control indicators. This research provides reference for the safety evaluation of grouted sleeve connections for prefabricated structures.

Seepage Characteristics Analysis on Earth Dams Considering Polymer Cutoff Wall with Construction Defects

In recent years, non-water reaction polymer grouting is a new technology for anti-seepage and reinforcement that has been widely employed in anti-seepage projects. However, there is little research on the consequence of defective polymer cutoff walls affecting the seepage safety of earth dams. To analyze the influence of the number, location, and randomness of defects in the wall on seepage characteristics of the earth dam, a three-dimensional finite element model of a typical earth dam with the polymer cutoff wall is established by numerical simulation technology. The model reflects the real geometry of the polymer cutoff wall as well as the internal common construction defects—windows and uneven thickness. The results indicate that construction deficiencies, especially defect rate and thickness uniformity, have a negative effect on the actual anti-seepage performance of the polymer wall. Eventually, the seepage safety of the earth dam may be endangered due to overestimation of the actual impermeability, if only assuming the cutoff wall is intact. Therefore, the index reflecting the integrity and the impermeability of the polymer cutoff wall is proposed, and the corresponding proposals are offered based on calculation results.