89
Timber Bridge Failure
P10=1-‐[(1-‐0.0376)*(1-‐0.6409)] P10=0.6544
P8=1-‐[(1-‐0.0014)*(1-‐0.0294)*(1-‐0.0071)] P8 = 0.0376 Superstructure deterioration
0.0014 Deck
0 Kerb
P9=1-‐[(1-‐0.0455)*(1-‐0.5242)*(1-‐0.2094)] P9=0.6409 Substructure Deterioration
0.0294 Girder
0.0071 Corbel
0.5242
0.0455 Pile
Headstock
0.2094 Whales and bearings
Figure 4: FTA for the hypothetical bridgeFigure 4: FTA for the hypothetical bridge
It is assumed that an element
past developments in Australia.
Weena Lokuge on 07 3470 4477 or
It fails is assumed an 4. element fails its CS replacement reaches 4. For Weena.lokuge@usq.edu.au. the hypothetical bridge, there is when its CSthat reaches For Duewhen to the limited the hypothetical bridge, there is budget, timber bridges are still in 65.44% chance that it will fail in 2018 and the major contribution cReferences omes from the substructure. This 65.44% chance that it will fail in service but their high maintenance Crawford, S. (2014). “Timber is e2018 vident rom the contribution inspection data costs in Table 2. recognized and and fthe major are well
Bridge Management: Past, Present become a challenge to bridge and Future”. Engineering and management agencies. This study Technology Forum, TMR. has presented a condition-based reliability method that utilizes the Lokuge, W., Gamage, N. and Proposed Markov process method can be combined with the fault tree analysis to predict the Discussion and limitations visual inspection reports of timber Setunge, S. (2016). “Fault tree Proposed Markov process bridges to the given future the inspection analysis method probability of failure of a timber bridge of predict interest report for is deterioration available for the method can be combined with condition of bridge components. of timber bridges using an current year. There ato re predict several limitations of the byproposed transition probability matrix as it is based the fault tree analysis This is achieved adopting the Australian case study.” Build the probability of failure of a stochastic Markov model, which only on limited number of inspection reports. It can be applied to a bridge having similar attributes. Environment Project and timber bridge of interest given is more suitable than the linear Management, 6(3), 332 – 344. Therefore the report model can be further refined if a large database can be developed so that bridge the inspection is available and non-linear deterministic Ranjith, S., Setunge, S., Gravina, for the current year. There are models. Furthermore, the failure elements can be categorised based on similar attributes. It is assumed the bridge failure occurs R. andthat Venkatesan, S. (2013). several limitations of the proposed probability of the whole timber “Deterioration Prediction of Timber when all the elements reach CS4. While reaching CS4 will be critical for some elements, it may not transition probability matrix as it bridge can also be assessed by Bridge Elements Using the Markov based onlyfor on o limited be isthe same ther enumber lements. using the fault tree analysis. The Chain.” Journal of Performance of of inspection reports. It can be predicted failure probability of Constructed Facilities, 27(3), 319applied to a bridge having similar timber bridge and its components Conclusion 325. attributes. Therefore the model can be used to reduce inspection can be further refined if a large Sonnenberg, A. (2014). maintenance cost through Timber bridges the legacy of and past developments in Australia. Due to the limited replacement database can be are developed so “Australian Bridge Inspection prioritization and timely manner, that bridge elements can be Processes.”<https://www.pittsh. ensuring the safety of timber budget, timber bridges are still in service but their high maintenance costs are well recognized and categorised based on similar com.au/cms_uploads/docs/ bridge network. become a challenge bridge has presented a condition-‐based attributes. It is assumedto that the management agencies. This study australian-bridge-inspectionbridge failure occurs when all More inspection data together processes.pdf> (Retrieved 22 reliability method that utilizes the visual inspection reports of timber bridges to predict the future the elements reach CS4. While with relevant factors such as daily August 2017). condition of bwill ridge components. Ttraffic his is volume achieved y adopting the stochastic Markov model, which is reaching CS4 be critical for andbenvironmental Wilson, M. (2016). Deterioration somesuitable elements, itthan may not the data are needed fordeterministic accurate more the belinear and non-‐linear models. the failure of TimberFurthermore, Bridges Using a Fault same for other elements. prediction in order to utilise the Tree Analysis. BEng (Honours), probability of the whole timber bridge can also be assessed by using the fault tree analysis. The proposed method efficiently. University of Southern Conclusion predicted failure probability of timber bridge and its components can be used to reduce inspection Queensland. Timber bridges are the legacy of For more information contact comes from the substructure. This is evident from the inspection data Discussion in Table 2. and limitations
and maintenance cost through prioritization and timely manner, ensuring the safety of timber bridge network. Engineering for Public Works | September 2017