Bearing Replacement on Eleven Heavy Haul Rail Bridges for Roy Hill

LEC have been a key technical advisor to Roy Hill throughout their ongoing heavy haul rail bridge bearing replacement program, from feasibility desktop studies through to advanced finite element analysis and bearing replacement.

---

DESKTOP STUDY OF HEAVY HAUL RAIL BRIDGES

FOCUSING QUESTION

Would it be feasible for the existing rail bridges to withstand an increased axle load and thus enable Roy Hill to increase their rail haulage capacity whilst utilising their existing infrastructure?

THE SOLUTION

LEC undertook a desktop study of three selected bridge spans to determine the maximum load carrying capacity of the existing waterway and overpass steel girder rail bridges along Roy Hill’s mine-to-port rail corridor.  Design checks of the main bridge components were carried out for strength (i.e. bending & shear) and serviceability.

THE LEC ADVANTAGE

Based on the outcome of the desktop study, LEC were able to advise Roy Hill of several opportunities that could be explored to increase the axle load on the bridges, such as detailed assessment using finite element analysis (FEA), site deflection & strain gauge measurements to determine the actual Dynamic Load Allowance (DLA), and de-rating of the bridge design load factors.

---

DETAILED ANALYSIS OF HEAVY HAUL RAIL BRIDGES

FOCUSING QUESTION

Determination of the actual Dynamic Load Allowance (DLA) for selected heavy haul rail bridges.

THE SOLUTION

Detailed finite element analysis (FEA) was undertaken by LEC to obtain analytical stress results, which were then compared with on-site strain gauge measurements obtained by Roy Hill’s sub-contractor.  This enabled LEC to determine an actual DLA for these bridges.

THE LEC ADVANTAGE

A detailed three-dimensional finite element model of the rail bridges was created by LEC in MSC.FEA using predominantly QUAD4 plate elements (four noded quadrilateral isoparametric element) and HEXA elements (eight-noded brick elements) were used to model the concrete deck. MSC.FEA is a state-of-the-art finite element analysis software package which is well-suited to this type of application.

---

VISUAL INSPECTION OF HEAVY HAUL RAIL BRIDGE BEARINGS

FOCUSING QUESTION

Roy Hill’s rail line has 11 steel girder rail bridges that form part of the vital link between their mine operations and port export facility, and their safe operation is reliant on the condition of the bridge bearings.

THE SOLUTION

Periodic visual inspections of the bridge bearings were undertaken by LEC to monitor the deterioration rate of the bearing by means of measuring the vertical gap between the upper and lower half of the bearing.

THE LEC ADVANTAGE

The team at LEC were able to provide recommendations based on the periodic measurement data.  This allowed Roy Hill to prioritise the bearing replacement programme accordingly.

---

BRIDGE BEARING DESIGN REVIEW

FOCUSING QUESTION

Roy Hill are replacing the existing elastomeric pot bearings with spherical bearings and the technical aspects of this change need to be fully understood to ensure safe & reliable operation.

THE SOLUTION

LEC carried out a technical review of the new spherical bearing design, including reviewing the design criteria, design loads & parameters and undertaking structural design checks (such as bolt shear capacity & weld design calculations).

THE LEC ADVANTAGE

During the design review, LEC identified some anomalies in the design loads which were able to be resolved with the original bridge designer and the new bearing supplier. LEC’s dimensional reviews, based on both documentation and site measurements, ensured the new spherical bearings will fit the existing bolt arrangements.

---

TECHNICAL ASSISTANCE DURING BEARING CHANGEOUT

FOCUSING QUESTION

To minimise disruption to heavy haul rail operations, the bearing changeouts were scheduled during tight shutdown windows.

THE SOLUTION

LEC provided on-site technical support for the bearing changeouts to enable quick resolution of any technical queries.

THE LEC ADVANTAGE

By collaborating with Roy Hill and their sub-contractors, LEC were able to ensure the bearing changeouts occurred on schedule and in accordance with the design intent.

---

SUMMARY OF SERVICES PROVIDED BY LEC TO ROY HILL

• Structural Integrity Assessment

• Advanced Finite Element Analysis

• Site Inspections of Existing Bearings and Dimensional Measurements

• Independent Review of the New Bearing Design

• Technical Assistance during the Installation of the New Bearings

---

Structural Design Review of a Tandem Rotary Tippler

LEC has recently completed an independent third-party structural design review of a new tandem rotary tippler and its associated positioner and wheel grippers. The new tippler was procured in order to increase the annual export throughput of an iron ore port.

Finite element model of the tippler and positioner structures

Typical fatigue stress range calculations

Detailed structural modelling and analysis was carried out independently using advanced Finite Element Analysis (FEA). Due to the cyclical motion of the tippler, design checks were focused on the fatigue service life assessment. Stress fluctuation due to the rotating motion of the tippler was calculated by analysing the tippler in several angular operating positions.

The independent design review was predominantly carried out in parallel with the Original Equipment Manufacturer’s (OEM) design process to meet the stringent project schedule. Design anomalies and structural non-conformance with the relevant design codes were promptly communicated to the OEM, thus allowing any required modification to the design to be implemented early in the design phase. This reduces the risk of potential costly production delays due to design issues and the associated on-site remedial work as well as the potential for commercial and/or legal disputes.

LEC also carried out a design review of the vertical lifting arrangement and transport saddles for land and sea transportation of the tippler cage structure, from the OEM’s fabrication yard to the owner’s site.

Design Verification of Drum Conditioner for Lithium Plant

LEC undertook finite element modelling, analyses and design verification of a drum conditioner for a lithium plant in Australia, which included:

• Design code compliance checks in accordance with AS 3990

• Buckling analysis using MSC.Nastran

• Natural frequency analysis using MSC.Nastran

• Fatigue endurance limit calculations in accordance with the requirements of BS 7608

The three-dimensional geometric model was discretised using predominantly MSC Nastran’s QUAD4 plate elements (four-noded quadrilateral isoparametric element) and where necessary TRIA3 (three-noded isoparametric triangular elements). MSC Nastran’s HEXA (eight-noded isoparametric solid elements), PENTA (six-noded isoparametric solid elements) and TETRA (four-noded isoparametric solid elements) were used locally to model the tyre support region closer to the exit end diaphragm to simulate the weld details for fatigue assessment. Fine mesh was adopted in the regions where fatigue assessment was required.

As a result, a design verification report was prepared by LEC containing proposed structural modifications for compliance with the applicable codes and standards.

Weighing of a Stacker Reclaimer

A rail-mounted bucket wheel stacker reclaimer had recently been refurbished following a partial structural failure, but before it could be returned to service it was necessary to weigh the machine to confirm its as-built condition matched the design intent for balance, stability, slew bearing loads and wheel loads.

LEC prepared a weighing method statement and undertook on-site supervision of the weighing, which was undertaken by jacking the eight-wheel bogie structures.

LEC then processed the site measurements to calculate the total weight and weight distribution (centre of mass) of the stacker reclaimer, and compared these to the design values to determine whether re-ballasting might be necessary to ensure the slew bearing service life would not be compromised due to an out-of-balance condition.

Finite Element Analysis of 3500t Sugar Bin

As part of an independent design review, LEC undertook finite element analysis (FEA) and design verification of a 3500-tonne capacity sugar bin.

LEC independently created the finite element model using MSC Patran based on the engineering design drawings of the proposed sugar bin, and the design loads were determined in accordance with the requirements of AS 3774 – Loads on Bulk Solids Containers.

The finite element analyses results were used in the design verification calculations in accordance with the requirements of AS 3990 and AS 4100, and a linear buckling analysis using MSC Nastran was carried out to identify any local member or plate buckling issues present in the proposed bin design.

The FEA results and design verification report were provided by LEC to the client to highlight any components of the sugar bin structure which did not comply with the requirements of the Australian Standards, to enable design modifications to be undertaken prior to fabrication.