Concrete Repair, Rehabilitation and Retrofitting IV

Proceedings of the 4th International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR-4), 5-7 October 2015, Leipzig, Germany

Frank Dehn, Hans-Dieter Beushausen, Mark G Alexander, Pilate Moyo

• Publisher: CRC Press
• Year: 2015
• Print ISBN:
  9781138028432
• eBook ISBN:
  9781317388784
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

The Fourth International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2015) was held 5-7 October 2015 in Leipzig, Germany. This conference is a collaborative venture by researchers from the South African Research Programme in Concrete Materials (based at the Universities of Cape Town and The Witwatersrand) and the Material

Concrete repair, rehabilitation and retrofitting

The construction of the bridge over the Vaal River in Warrenton—a case study

Tiago Massingue

The South African National Roads Agency Limited SOC (SANRAL), South Africa

ABSTRACT

The construction of the bridge over the Vaal River in Warrenton replaces an existing low level bridge that had been in operation for 83 years. From an economic perspective, the new bridge offers significant improvements in terms of living conditions to the people of Mahareng as during the rainy season they were deprived from crossing the Vaal River for approximately six weeks. Specific objectives outlined during the design stage, highlighted to the following improvements over the existing low level bridge:

• providing an extra lane capacity, improving traffic flow in both directions,

• providing new pedestrian footpaths and thus enhancing safety,

• providing safer road shoulders for bicycles crossing the bridge,

• improved discharge capacity during high floods of the Vaal River,

• reducing the risk of floods which have in the past affected the local community in Warrenton,

• improving the economic development for Warrenton,

• Enhancing the overall traffic flow and safety on the N18 as a National Road.

The existing low level bridge was to be demolished in order to accommodate the new one. However the existing legislation in South Africa [Section 34 Act 25,1999—South African Heritage Resources Agency] outlines that any structure that is in existence for over 60 years must be protected in terms of heritage requirements. Therefore, while the above objectives were still justified, Structural Retrofitting for altered service conditions was to be given to the old structure in order to preserve its historical significance. The Project has shown at the end that new and old can come together in a proactive bridge development interface. Critics argue that the old bridge has enhanced the significance of the new one. Additional benefits were gained by means of job creation, training programs and the SMME development in the area. This is a positive South African story about the development of bridge infrastructure projects as part of the South African National Roads Agency’s mandate to promote and develop road network of the country.

INTRODUCTION

Historically, the original bridge over the Vaal River in Warrenton opened for traffic on the 29 October 1931 and has the following dimensions: 55 spans of 16 m each and 2.5 m height. To accommodate pedestrians on the single carriageway bridge of 3 m width, 1 m × 0.6 m precast concrete side sidewalks were provided and painted in yellow for aesthetics Although it contained several constraints in terms limited bridge cross section allowing one direction of traffic flow at a time and overtopping by floods causing the isolation of local Municipality up to six weeks, it has been successfully in use for 83 years

The National Roads Agency initiated the process to revert this situation by defining a design team for the new bridge in 2007. Ravi Rooney and Edwin Kruger were responsible for the Drainage and Structural Design. Petronella Theron was assigned to work on access roads design while T Massingue would be responsible for the overall project management and implementation in the Western Cape. Limited scope was later assigned to expert consultancy firm, SNA to oversee some of the SANRAL functions and later the supervision of works. The new design criterion is based on the South African design requirements in terms of the Technical Recommendations for Highways THR 4 Road Category, THR 7 for Bridges and the National Water Act 1998, Section 21(c): Impeding or diverting the flow of water in a watercourse and Section 21(i): Altering the bed, banks, course or characteristics of a watercourse.

This paper deals with the construction of a new bridge, Bridge No. B0067 and the associated road works for the realignment of National Route 18 Section 1, N18-1 across the Vaal River at Warrenton, in proximity to and downstream the old existing single lane, low level river bridge, Bridge No. B2284 on N18-1. The new designed outlined a total length of realignment of N18-1, inclusive of the new bridge to was 1.48 km and the bridge length is 368 m.

Work undertaken in terms of the contract includes:

• Establishment of the contractor;

• The provision of offices, laboratories and housing for the engineer’s site personnel,

• The accommodation of traffic. The existing low level river bridge remained in use for the accommodation of traffic throughout the construction of the project.

• The relocation of existing electrical (Eskom and Municipal) and telecommunication services,

• The construction of roads works,

• The construction of surface drainage,

• The construction of subsoil drainage

• The construction of the new Bridge B0067 across the Vaal River.

• The rehabilitation of the existing low level bridge, which was retained due to the historic significance thereof,

• Ancillary work consisting of:

• The installation of service ducts;

• The construction of segmental block paved sidewalks

• The construction of gabion erosion protection, including the protection of approach fills to the new bridge across the Vaal River;

• The erection of guardrails;

• The erection of fencing,

• The relocation of existing road signs and the erecting of new road signs

• The application of road markings,

• The establishment of grassing,

• Finishing of the road and road reserve and the treatment of the old road;

• The erecting of the following at the existing low level bridge across the Vaal River;

• Bollards to prevent vehicular access to the bridge

• Information signs regarding the use of the bridge

• The construction of a segmental block paved rest area on the Warrenton side of the Project. A commemorative plaque providing a brief background of the existing low level bridge and new bridge was erected at the rest area. A blocked paved walkway was constructed from the rest area to the existing low level bridge.

• The erecting of the overhead lighting over an 800 m length of the project, including across Bridge no. B0067.

PROJECT OUTPUTS

At the end of the 22 months construction period, the following road and bridge construction outputs were achieved:

• 144 Precast Beams

• 27.2 tonnes per beam;

• 16 Prestressing Strands,

• Total length presstressing Strand in Beams approximately 59.04 km,

• Total Length Rebar in Beams: approximately 209.4 km

• Elastomeric Bearings: 288

• Total Volume Concrete in Bridge: approximately 6295 m³

• Total Area Formwork (Temporary and Permanently): Approx 10350 m²

• Mass of Total Structure: Approx 16000 tonne

In line with the South African Government’s Policy to address poverty the following aspects were also included in the project:

• Labour Intensive Methods,

• The Contract Participation Goals (CPG)

• Training & Skills transfer Programs, and

• The Socio-Economic Development,

• Environmental Control & Mitigation Actions

As a result, the proportion of persons-hours in terms of employment throughout the project duration was: Male: 255884 and Females: 38392. The value of employment of local persons was in the order of R5.6 million. The value of employment of all persons was: Male: R10.9 million and for Female was R1.1 million, totaling overall R12 million.

The overall project cost was R86 million which is approximately EURO 8 million.

Numerical study on effect of ductility in the flexural capacity enhancement of RC beam strengthened with FRP

A. Kashi & M.Z. Kabir

Department of Civil and Environmental Engineering, AmirKabir University of Technology, Iran

F. Moodi

Concrete Technology and Durability Research Center. AmirKabir University of Technology, Iran

ABSTRACT

The repair, rehabilitation and strengthening of Reinforced Concrete (RC) beams is a challenging engineering problem. Flexural strengthening of these members is achieved by attaching FRP strengthening system to the tension face of a flexural member. Previous studies have demonstrated by attaching externally bonded fabric of Carbon Fiber Reinforced Polymer (CFRP) laminate to the tension side of reinforced concrete beams can increase stiffness and maximum load of the beams.

In this report, a finite element model was posted out to examine the effect of ductility on the flexural capacity enhancement of RC beams after attaching CFRP. Two cases of RC beam (552 mm × 305 mm × 6840 mm) were analyzed by FE modelling (Figure 1). The field of longitudinal flexural rebar has been dissim...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• ICCRRR committees
• Concrete durability aspects
• Condition assessment of concrete structures
• Modern materials technology
• Concrete repair, rehabilitation and retrofitting
• Performance and health monitoring
• Education, research and specifications
• Author index