Load Rating - 2012-256 - Responsive - 6

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Report

City of Vancouver

Burrard Street BridgeRehabilitation DesignLoad Rating

May 2012



REPORT

Executive Summary

As part of the rehabilitation program for the Burrard Street Bridge, a load rating was conducted for the

Burrard Street Bridge following the bridge inspection in 2011. The analysis was performed in accordance

with the Canadian Highway Bridge Design Code (CHBDC CAN/CSAS6-06), Clause 14.

The bridge was analysed considering up to six traffic lanes using the design vehicle CL625 (64 tonnes) in

combination with distributed live load. This load corresponds to the design load for new highways and

bridges in British Columbia. The assumption of six traffic lanes is expected to accommodate the future

bridge laning configurations envisaged and provide an appropriate assessment of all major structural

elements. Depending on the configuration and details adopted, adding fences and barriers is not expected

to negatively affect the assessment.

The Burrard Street Bridge comprises of two major elements the concrete approaches and the steel truss

spans. Our analysis indicates that all steel truss members have adequate capacity. However, our analysis

of the gusset plates using a simplified method did not find sufficient capacity in all cases. More rigorous

analysis of the remaining gusset plates is required. We recommend additional finite element analysis of the

remaining gusset plates in order to verify their adequacy.



ReportBurrard Street Bridge Rehabilitation Design

Load Rating

Table of Contents

SECTION PAGE NO

Executive Summary iTable of Contents iii

1 Introduction 1

1.1 Description of the Existing Bridge 1

1.2 Existing Information 3

1.3 Allowances for Future Loading 3

s.13(1); s.15(1)(l); s.17(1)(c), (d), & (f); s.18(a); and s.19(1)(b)



City of Vancouver

s.13(1); s.15(1)(l); s.17(1)(c), (d), & (f); s.18(a); and s.19(1)(b)



REPORT

1 Introduction

In 2011, the City Of Vancouver (City) retained Associated Engineering (AE) to carry out a

bridge rehabilitation program for the Burrard Street Bridge. This load evaluation is part of that

assignment.

1.1 Description of the Existing Bridge

The Burrard Street Bridge was built in the 1930's and is one of the primary landmarks in the City of

Vancouver. The general arrangement (GA) is included in Appendix A of this report. The bridge,

shown in Figure 1-1, consists of steel truss main spans and concrete viaduct approaches.

Figure 1-1

Burrard Street Bridge



City of Vancouver

In 2000, a seismic upgrade was undertaken at Bent 24 in the north approach to the bridge. The

piers and footings were strengthened and longitudinal restrainer and cross bracing seismic

members were installed. Similarly in 2005, seismic upgrades were undertaken for the south

approach spans, including Bents 4, 7, 10, 13, 16, and 19, and a shear wall was installed to

strengthen Bent 4. The seismic upgrading work has no impact on the current load rating study.

The City of Vancouver has also informed us that currently there is a program underway for

replacement of the bearings supporting the approach spans of the Burrard Street Bridge. Allexisting rocker bearings will be replaced with disk bearings; however, the current articulation will be

maintained. In addition, disk bearings will be installed to replace the sliding bearings at Bent 4, and

the span length between Bents 3 and 4 will be decreased by 200 mm.

The bridge has a roadway width of 18 288 m (60-0). The current deck arrangement has a total of

five lanes of vehicular traffic and one lane of bicycle traffic. The load rating analysis was carried ou

based on up to six lanes of traffic to produce the most severe loading condition.

The two identical trusses for both types of deck-truss span are spaced 13 106 mm (43-0) apart

and have a depth of 9144 mm (30-0) between top and bottom chord centerlines. The top chords,

bottom chords, diagonals and load carrying vertical members consist of built-up box sections. The

178 mm (7) thick reinforced concrete deck is supported by steel S24 x 80 stringers spaced at

1828 mm (6-0) The stringers span 6706 mm (22-0) for the 176 truss and 6604 mm (21-8) for



ReportBurrard Street Bridge Rehabilitation Design

Load Rating

1.2 Existing Information

The following reference documentation was reviewed and considered in conducting this load

evaluation.

x Record Drawings: Burrard Street Bridge Drawings No. 34-E-0 through No. 34-E-53.

x Associated Engineering Close Proximity Inspection Report , February 2012.

x Delcan Burrard Street Bridge Load Evaluation Report , November 2009.

x Seismic Retrofit Drawings:

x Burrard Bridge Bent 24 Seismic Upgrading Drawing No. 1533 1 through 7;

x Burrard Bridge Seismic Upgrading Drawing No. 1720 1 through 17;

x Burrard Bridge Seismic Upgrading Phase II Drawing No. 1170 40 through 59.

1.3 Allowances for Future Loading

At this stage we do not know what bridge modifications may be implemented, and therefore a future

loading allowance cannot be pre-determined. Accordingly, we have not built any allowance for

future loading into our load rating of components. However, as a result of the structural

assessment, we are able to comment on the implications of adding loads to the bridge.

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