ESW Crane Gantries REPORT- Prelim

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PROJECT ENGINEERING SERVICES

REPORT: Engineering Services Workshops -

Crane Gantries Invest igat ionRevision History:

DateReportStatus

Written by Reviewed byReviewed

Date

Issued to

Name Purpose

2012-04-11 Draft M Rakgotho K Hutchinson Review

Approved by:

NameECSA Reg.

No.Signature & Stamp Date


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ii)

TABLE OF CONTENTS

PAGE(S)

1. Purpose ..................................................................................................................... 12. Background ............................................................................................................... 13. Structural Elements.................................................................................................... 14. Recommendations ..................................................................................................... 35. Conclusion ................................................................................................................. 3APPENDIX A ......................................................................................................................... 4APPENDIX B ......................................................................................................................... 5APPENDIX C ........................................................................................................................ 6APPENDIX D ........................................................................................................................ 7

LIST OF FIGURES

Figure 1: ESW Girder Supports ..............................................................................................2


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1. Purpose

The purpose of this report is to give commentary on the structural suitability of the ESW

workshops crane gantries to carry a second 15 tonne crane.

2. Background

The Engineering Services Workshops is contemplating purchasing a new 15 tonne crane.

The 15 tonne crane is aimed at replacing the existing 5 tonne crane, which operates on the

same gantries as another existing 15 tonne crane, with the view of increasing the operational

capacity of the gantry and/or workshop. The proposed arrangement is to install this new 15

tonne crane also on the same gantry as the existing one. The Project Engineering Services

Civil Engineering Division was then requested to investigate the suitability of the crane

gantries to deal with the proposed arrangement.

3. Structural Elements

3.1 Crane Gantries

The investigation of these elements was done in three phases:

a) Examining the existing scenario;

b) Studying the effects of the installation of a second 15 tonne crane;

c) Estimating the possible design functionality of the gantries.

Findings:

The analysis results of these phases are attached in Appendix A, B and C for the respective

phases, and discussed below.

Phase a)

The current setup gantry comprises of:

Main Beam Capping Beam

533x210x101 I1 PFC 300x100 Channel

The analysis of this phase indicated that the current scenario does not satisfy the code

requirements for member stability and deflections (horizontal deflections in particular).

For member stability, the code requires that: =

+

1.

This requirement is only satisfied when the fail-safe-switch works optimally, with a shut-down distance of 3.75 m or more. This, however, would not fall within Ultimate Limit Statedesign as defined in the code, as for this limit state, one has to design for the worst possiblecase and that would suggest an operational failure of the switch. When assuming a failure ofthe switch, the stability requirement is not met on the two outer-most spans in both ends ofthe system.

The resultant horizontal deflection from the two cranes operating together exceeds the limit

stated in the code:: 600.


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2)

Phase b)

The analysis of this phase simply indicated the already expected results. An installation ofthe second 15 tonne crane exacerbates the Phase a) findings.

Phase c)

In this phase, I investigated the possible size crane that the gantries could have beendesigned for, my subject. It appeared in the analysis that current the crane gantries couldhave actually been designed to carry only one 15 tonne crane.

This, however, cannot be confirmed due to the lack of original design information of theworkshops.

3.2 Gantries Supports

The support-arrangement used in the workshops for these gantries is in accordance with theguidelines provided in South African Steel Construction Handbook, 6th Edition for heavy

duty cranes. The 5.5m high columns currently on site (254x146x43) can carry the resultantloads induced by the addition of a second 15 tonne crane at both limit state designs. This isso in that the 70x70x6 Equal Angle bracings installed on both sides of the I-section (as seenin Figure 1 below) significantly lower the effective length of the columns

The columns are also fitted with a 20mm thick base-plate that is thick enough to cope withthe new loads. The four (4x) M24 HD Bolts are found to be sufficient to deal with theresultant loads as well.

Figure 1: ESW Girder Supports


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3)

3.3 Column foundations

It is not possible at this stage to comment on the ability of the columns concrete foundations

to deal with the proposed scenarios resultant loads. This is primarily due to the fact that

there is neither design nor As-built drawings of the workshops.

4. Recommendations

It is recommended that a design project be commissioned to appropriately size the crane

gantries before an additional 15 tonne crane is installed. A preliminary analysis and sizing for

the proposed scenario (additional 15 tonne crane) yielded that the following gantry setup be

adopted (see Appendix D for details):

Main Beam Capping Beam

533x210x101 I1 PFC 300x100 Channel

It is also advisable to bring the existing scenario to compliance with the South African

Standards as the workshop may not necessarily have sound legal arguments should a major

accident occur and the gantries be subjected to their ultimate design loads.

It is further recommended that the workshops be re-drawn for proper record keeping, and it

would be advisable that this exercise be carried out by the SARPES department to ensure

compliance with Anglo Gold Ashanti standards and specifications.

5. Conclusion

The existing crane gantries need further modifications to meet the proposed scenario where

two 15 tonne cranes can operate together on the gantry. The modifications are detailed in

the recommendations section.

On the column foundations, it can be assumed that they have sufficient capacity to deal with

the proposed scenarios resultant loads. This assumption is based on the fact that the

columns appear to have been over-designed in the first place. If this assumption is not

sufficient, an X-ray scan of the foundation could then be commissioned.


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4)

APPENDIX A


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6)

APPENDIX C


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7)

APPENDIX D

ESW Crane Gantries REPORT- Prelim

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