# Remedial Modelling of Steel Bridges through Application of Analytical Hierarchy Process (AHP)
## 8 Conclusions  
The digital revolution and artificial intelligence have opened the door for smarter infrastructure. Nowadays, scientists and practitioners have the technology to understand how a tunnel, a building, a bridge, or a railway line is performing during its service life. This will lead to improved asset management, as decision makers will know how to prioritise the assets and when, and how, to manage it more competently. Application of decision support models for management of civil infrastructure also enables more economic design, reduced costs and greater efficiencies, both in the cost of construction and in the subsequent asset management costs, delivering benefits to multiple stakeholders [32]. Corrosion and fatigue can have a detrimental effect on the serviceability and structural lifespan of a steel bridge. Corrosion caused by the oxidation of the iron can attack the structure and eventually shrink the cross-sectional area of the member. It can also freeze joints which are assumed to be free \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Criteria**} & \multirow{2}{*}{**Alternative**} & \multirow{2}{*}{**Weights/\%**} & \multirow{2}{*}{**Splice Plates**} & **Steel Plate** & **FRP** & **Partial Member** \\  & & & & & **Strengthening** & **Strengthening** & **Replacement** \\ \hline Service Life & 13.76 & 3 & 4 & 4 & 5 \\ Safety & 45.81 & 4 & 4 & 4 & 5 \\ Cost & 26.27 & 3 & 2 & 3 & 2 \\ Environmental Impact & 4.53 & 3 & 3 & 4 & 3 \\ Traffic Disruption & 6.63 & 2 & 2 & 3 & 1 \\ Aesthetic Appeal & 2.99 & 2 & 2 & 3 & 4 \\ Overall Score & 100 & 336.16 & 204.37 & 364.07 & 382.57 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Global Priorities of Different Major Strategies. to move, such as pins, bearingss and hangers. Fatigue cracks initiating from high stress regions can propagate through the members in the structure, essentially causing the member to loose cross-sectional area. Both of these reduce the load carrying capacity of the bridge. This research has proposed a decision system for the remediation of steel bridges based on multi-criteria analysis. The mechanism of deterioration on steel bridges were investigated and identified and the remediation treatments used for these deterioration mechanisms have been analysed. The decision system based on the Simplified Analytical Hierarchy Process (S-AHP) has been proposed as the main model for strategy selection. In this framework the eigenvector approach of the AHP is chosen for criteria weighting. The S-AHP accounts for the uncertainty and complexity associated with the values representing the relative importance while creating a sensitive evaluation of the consistency in judgments. The system allows the user to define the benefits of the criteria that are important to them, so that an appropriate treatment can be found for the deteriorated structure. The system was then tested to ensure that the model can be used in a practical environment. One of the key strength of the system is that the main model can be applied to other types of civil infrastructure such as dams, tunnels, pavements and buildings. As a subsequent outcome of this study, several areas have been identified to require further research and development, in order to improve the versatility and practical application of the system. The recommendations for future study are to:  
* Extend the capabilities of the proposed system to consider impact damage, as this deterioration mechanism is often encountered by engineers and bridge inspectors. This would further enhance the usefulness of the system as an integrated leaning and accountability tool. * Incorporate relevant standards and procedures used during the rehabilitation process with the recommendation. This would require the system to consider a broader range of site specific constraints, to ensure all relevant policies were addressed. Additionally, the system would need to be reviewed on a consistent basis to guarantee superseded standards and policies were updated, to avoid possible litigation for misuse.