Abid Nadeem

INFLUENCE OF STEEL FIBRES ON STRENGTH AND DUCTILITY OF NORMAL AND LIGHTWEIGHT HIGH STRENGTH CONCRETE

Abstract This paper presents the results of a series of experiments conducted to investigate the effectiveness of fibre inclusion in the improvement of mechanical performance of concrete with regard to concrete type and specimen size. Lightweight aggregate concrete and limestone aggregate concrete with and without steel fibres were used in the study. The compressive strength of the concrete mixes varied between 90 and 115 MPa and the fibre content was 1% by volume. Splitting tests on prisms and three-point bending test on notched beams were carried out on specimens of varying sizes to examine the size effect on splitting strength, flexural strength and toughness. The experimental findings indicate that the low volume of fibre has little effect on compressive strength but improve remarkably splitting tensile strength, flexural strength and toughness. The increase in splitting tensile strength, flexural strength and toughness index for lightweight concrete seems much higher than that of normal aggregate concrete. The size effect on prism splitting tensile strength is not significant beyond a critical (transition) size. There are apparent size effects on flexural strength and toughness index. As the specimen size increases, splitting and flexural strengths appear to decrease, and fracture behaviour tends to be more brittle.

Government roles in implementing building information modelling systems: Comparison between Hong Kong and the United States

Purpose – Building information modelling (BIM) is a paradigm shift in the architectural, engineering and construction industries which transforms processes to achieve greater efficiency and effectiveness. The purpose of this paper is to highlight the implementation of BIM in Hong Kong and the USA and recommend strategies for BIM implementation in Hong Kong.Design/methodology/approach – A literature review of BIM initiatives taken in Hong Kong and the USA was conducted including the government policy, guidelines, standards and implementation status. Findings from the literature review were complemented with insights obtained through focused interviews of experts in the field for arriving at recommendations based on the research. The principal investigator of this research also participated in the establishment of a BIM professional institute as one of the founding board members.Findings – As a result of studies performed for this paper, guidelines are proposed for BIM implementation in Hong Kong. The role ...

Attributes of Building Information Modelling Implementations in Various Countries

Abstract Various initiatives can be taken to implement building information modelling (BIM) systems in a country. The purpose of this article is to highlight critical initiatives derived from the review of BIM implementations in both the public and private sectors in six selected countries. The methodology adopted for structuring the study is to classify BIM initiatives for its implementation in policy, process and technology fields. A literature review of such BIM fields from the USA, Finland, Norway, Denmark, Singapore and Hong Kong is provided. Moreover, the experiences of authors in BIM research projects conducted in the past through questionnaire surveys and interviews are also utilized to synthesize the findings. The review suggests that, in several situations, BIM is implemented in conjunction with industry foundation classes for better integration and interoperability of various components of a BIM system. The types and roles of major stakeholders in promoting and providing support for the implementation, research and development of BIM systems are presented. The findings suggest that initiatives can be taken for policy formulation, BIM organization, information exchange capability, research areas identification, promotion, presentation and liaison of BIM programmes for an effective BIM implementation in a country.

Comparison of workability and mechanical properties of self-compacting lightweight concrete and normal self-compacting concrete

Abstract The workability and mechanical properties of self-compacting lightweight concrete and normal self-compacting concrete have been studied. Self-compacting lightweight concrete with a binder content of 500–650 kg m−3 and a density of 1650 kg m−3 was made using less superplasticizer and viscosity modifying agent and a lower water/binder ratio than normal self-compacting concrete. The bulk density was only 75% of normal self-compacting concrete but with a similar compressive strength. The elastic modulus was about 80% of that of normal self-compacting concrete. These results indicate that self-compacting lightweight concrete is excellent in workability and has a lower density, a higher compressive strength and a relatively high elastic modulus than normal self-compacting concrete using the same design principles.

Improving existing delay analysis techniques for the establishment of delay liabilities

When construction delays occur, it is necessary to ascertain the liabilities of the contracting parties and to direct the appropriate amount of resources to recover the schedule. Unfortunately, delay analysis and schedule compression are normally treated as separate or independent aspects. This paper examines the feasibility of integrating the delay analysis and schedule compression functions into a broad‐scoped two‐stage process. The main issue is shown to be the kind of delay analysis required for each stage of the process and seven existing techniques are illustrated for use in conjunction with schedule compression. Since the current form and assumptions of delay analysis techniques are unlikely to provide the necessary level of feedback reliability for recovering delays, it is necessary to modify these techniques by incorporating some means of delay type scrutiny, excusable delays updating, and treatment of concurrent delays. The modified delay analysis techniques can serve as a basis for negotiation between the client and contractor and hence improve the interdisciplinary relations.

Strengthening of concrete structures with FRP sheets and plates

Presents an overview and discusses the applications of fibre reinforced polymer (FRP) sheets and plates in the strengthening of concrete structures. An insight may be obtained from the discussions made to enhance the use of these techniques for productive use. In addition, selected case studies have been furnished where FRP materials have been used for repairing/retrofitting, emphasizing the application of different types of FRP materials in strengthening concrete structures. Concludes that the use of FRP material is rapidly gaining pace and replacing the traditional steel or metal based materials due to its enhanced properties and cost effectiveness.

Attributes of Building Information Modelling and its development in Hong Kong

Building Information Modelling (BIM) is a promising tool for facilitating automation in the construction industry. Since its inception in the early 80s, assisted by advancement in computing technologies, BIM is slowly replacing conventional 2-dimensional CAD technologies in a few countries. Also, standards and guidelines are being developed by various organisations for its unified use on architectural, engineering and construction projects. The attributes of BIM derived from its various definitions are discussed in this paper along with its utilisation trend in Hong Kong. A qualitative consideration of BIM is provided by the item analysis of BIM definitions. Evolution of the perceptions of architectural professionals about BIM in Hong Kong has been investigated by reviewing past studies and by use of a questionnaire survey. The major stakeholders driving the implementation of BIM in Hong Kong are identified. Finally, the studies of five selected cases of BIM implementation in Hong Kong are presented and the lessons learned from these cases are examined.

Fibre reinforced polymer materials for prestressed concrete structures

Fibre reinforced polymer (FRP) materials are currently used for concrete structures in areas where corrosion problems are serious. Recent applications of FRP rebars in normal reinforced concrete structures in fact cannot fully utilise the strength of FRP. A more rational use of FRP would be in the area of prestressed concrete (PC) structures. In spite of the superb strength provision of FRP tendons over steel tendons, use of FRP PC members is often questioned by practising design engineers. This is largely due to the brittleness of FRP tendons and lack of ductility in FRP RC structures. Recent research has demonstrated some important findings in promoting the confidence of adopting FRP RC beams. This paper reviews some recent work on the use of FRP in PC structures. Future possible research areas are also highlighted.

Flexural and split cylinder strengths of HSC at elevated temperatures

This paper investigates the effect of elevated temperature on the flexural strength (FS) and split cylinder strength (SCS) of high strength concrete (HSC). Four concrete mixes of 50, 90, 110, and 130 MPa grade were prepared and subjected to elevated temperature exposure of 200°C and 400°C, and cooled under slow and quick cooling conditions. In addition, 130 MPa grade concrete specimens were also subjected to 100°C and 600°C exposure temperatures to compare FS and SCS under elevated temperatures. It was observed that with the increase in the elevated temperature, the FS and SCS experienced significant losses. The loss was found to be higher for richer concretes. FS was observed to experience a sharp loss at low temperatures that became gradual later at high temperatures. SCS, however, experienced a gradual loss, though sharper than FS, with the increase in temperature. The results indicated that cooling had a significant effect on the residual values and quick cooling caused greater loss in FS and SCS, than slow cooling at elevated temperatures. The quick cooling was noted to produce maximum loss over slow cooling at temperatures around 400°C.

Using building information modelling to achieve lean principles by improving efficiency of work teams

ABSTRACT Both Building Information Modelling (BIM) and Lean principles have significant impact on efficiency and effectiveness during a project development process within the construction industry. It is widely accepted that BIM can be used as a tool to help reduce project cost; shorten project duration by optimizing the construction sequence; improving the coordination of project teams; providing communication platform for different disciplines; etc. A further exploration can be made to find out whether BIM can be used as a tool to help project teams to achieve the Lean principles. In this research, a hypothesis was developed to validate if BIM can be used as a tool to achieve the principles of Lean construction by improving the construction productivity during a project. Several metrics were investigated to measure the contributions of BIM towards project productivity. By analysing a case study, this paper explores the connection between BIM and Lean principles; the contribution of BIM in the improvement of coordination and collaboration of work teams; enhancement of project quality; and reduction of waste and cost.