The General Architecture of a European Bridge Management

7/29/2019 The General Architecture of a European Bridge Management

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The General Architecture of a

European BridgeManagement System

PhD. Student, MSc, Dipl. Eng. Laurentiu Pavelescu

Technical University of Civil Engineering Bucharest

Faculty of Railways, Roads and Bridges

Bucharest, Romania

[email protected]

INCER 2012Bucharest, Romania

July 2012 INCER BUCHAREST CONFERENCE 1


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I. INTRODUCTION

A so-called Bridge Management System (often

abbreviated as BMS) addresses all activitiesthroughout the life of a bridge from conception

through design and construction, and finally to

replacement or demolition and is aimed at

ensuring their safety and functionality.

This requires techniques and procedures that

ensure that bridges are regularly inspected and

assessed, and that appropriate maintenance is

carried out to achieve a required standard of

condition throughout their service life.



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BMS - principal modules:1. Inventory of the stock;2. Knowledge of bridge and element condition

and its variation with age;

3. Evaluation of the risks incurred by users (including

assessment of load carrying capacity);

4. Management of operational restrictions and of

the routing of exceptional convoys;5. Evaluation of the costs of the variousmaintenance strategies;

6. Forecast the deterioration of condition and the

costs of various maintenance strategies;

7. Socio-economic importance of the bridge

(evaluation of the indirect costs);8. Optimization under budgetary constraints;

9. Establishment of maintenance priorities;

10. Budgetary monitoring on a short and long-term

basis.



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Fig. 1: Interconnections between inputs,models and outputs for BMS (according to

BRIME)



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II. FRAMEWORK

There is no easy way to define the inter-

relationships between the BMS inputs, models

and outputsthere are many variables that amanager should take into account and this

yields very complicated flow charts for the

entire BMS, if one wants to use full names for

inputs, outputs and models.

The models inter-connections are explained

through the outputs of some models that can

stand as derived inputs for other models (see

Table 1).

The models are analyzed in accordance withthe two levels of management: the project and

network level.



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III. MODELS

The models range from a to j and they are the

essential key of deriving an output from an initial

input (keeping in mind that an output can play therole of a derived input for another model).

a. This model is used to derive a measure for the

condition of each structural element and

component of the bridge inspection byobservations, material testing and information in

the inventory.

b. The model b provides a measure for the

overall condition state of a bridge through thecombination of the condition state values for allelements and components.



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c. The model c is supposed to use

information in the inventory such as the

engineering calculations and the final

drawings to derive the initial loadcarrying capacity measured in terms of

load, reduction factor or reliability index.

At this stage, should be identified the

most structurally vulnerable parts of the

bridge as well.

d. The key point for this model is to predict

the variation of the condition of the

bridge, in its entirety, or of some

elements of the bridge. This prediction is

made with the aid of the test histories

and inspections conducted for the

bridges in the managers stock. Theresults can be presented in a discrete

fashion, i.e. for every n years we can

derive the so-called condition state-

time trajectory.



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d. The model e is the one that predicts

the imperative of maintenance works,

whenever the poor condition of a

specific bridge makes it unsafe /

inadequate for the general use. This is a

challenging matter for engineers andmanagers.

The following inputs are to betaken into account:

the latest load carrying capacity;the structurally vulnerable parts of the

bridge;

the condition state-time trajectory for the

vulnerable parts;information from the assessment history

of the bridge.



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e. Evidently, the manager and the

engineers will base their maintenance

strategies on the cause of the

deteriorations and they will implementthose strengthening / repairing /

consolidating techniques that best fit the

situation. It is a direct relationship

between the maintenance method and

the cost that is involved, so this model

should as accurate as possible.

f. One of the biggest challenges for a

bridge manager is to generate

economic viable solutions whenever the

traffic restrictions are imposed due to

maintenance work. There are means by

which the engineers can predict thecosts involved by these traffic disruptions,

using, for instance, traffic data, the

duration of the predicted restriction and

the type of vehicles that will be rerouted.



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g. There are several ways that a manager of a

pile of bridges can use in order to select the

correct maintenance strategy, such as the

analysis of the results generated byinventory, the cost of different interventions,

the cause of the observed deteriorations,

the costs generated by the traffic disruptions,

the minimum required life after the

consolidation / repair / strengthening of the

bridge, etc.

h. There are many intervention strategies that

an administrator can choose, but some of

them are imposed by the bridges condition.

If a bridge has a poor condition but it meets

the load carrying capacity demands, the

most likely strategy of intervention is ageneral repair. A preventive approach is the

right one whenever deterioration has not yet

occurred to a great level but the choice for

such an action will conduct to reducing the

rate of deterioration and lifetime costs.



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i. The final objective of a Bridge Management

System is to generate a maintenance

programme for every bridge in a specific pile

(we refer to this as the project level). Thisintervention should take into account

optimization methods for reducing the total

life-time costs and improve the general

condition based on factors such as:

information in the inventory;

the choice of optimal maintenance method;maintenance costs and lives;

delay costs;

the rate of deterioration (condition state-time

trajectories);

the life required of the bridge;

the extent of deterioration;the date when essential maintenance

becomes necessary;

the discount rate used in lifetime costing.



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The models from a to j are involved with

analyzing data and deriving based on them the

correct decisions about the intervention

strategies of particular bridges, the project levelof a bridge management system. The next four

models, model to model analyze and

conduct a manager to take the right decisions

for pile of bridges, the so-called network level of

a bridge management system.

The bridges chosen to be within the stock candepend on many factors such as:

the region of the stock of bridges;

type of road: European and national roads,

county roads, rural / local roads;

type of bridgehere we can imaginedifferent classification factors, such as

material, the obstacle they cross, etc.



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Sometimes, it is not feasible to undertake the

intervention operations for each bridge due to

the budgetary restrictions (the most pressingones) or due to different constraints that can

occur. This status quo involves a differential

approach for improving a whole network than

the particular operations a bridge needs in

order to be fully functional.

These considerations imply restrictions /constraints that the optimization should imbed,

such as:

budgetary constraints;

the efficiency of the whole network, ratherthan a particular bridge;

the public policies.



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The administrator is most likely to wish that his

policy targets (yet another constraint) for the

condition of the whole stock and individual

bridges are being satisfied. According to BRIME,some policy target parameters may include the

following:

number of bridges with load restrictions of

different degrees;

number of bridges with other traffic restrictions

number of substandard bridges;annual traffic delay costs due to restrictions

and maintenance works;

number of bridges overdue an inspection;

number of replacements each year;

average condition of the stock;

number of bridges with condition state greaterthan X;

number of bridges containing one or more

elements with a condition state greater than Y.



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IV. THE FRAMEWORK BASIC

INPUTSAs can be seen in Figure 1, a letter is assigned for every input,

varying from A, for Inventory up to O for the Policy

Parameter Targets. A full list is given bellow:

A - Inventory

B - Inspection

C - Test Data

D - Inspection history

E - Test history

F - Assessment history

G - Traffic data

H - Duration of restriction

I - Future maintenance free life

(MFL) of repair

J - Compendium of

maintenance life/costs

K - Future life required

L - Maintenance history/policy

M - Discount Rate

N - Constraints

O - Policy Parameter Targets



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V. THE FRAMEWORK

MODELLING

A list of the calculations (or models)

representing the actual means by which we

can obtain an output starting from an initialinput is presented below.

It should be underlined that the Roman lettersstand for the project level of a Bridge

Management System, whereas the Greek

letters represent the network level of a BMS.



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a Condition state of element

b Condition state for bridgec Assessment of LCC assuming no deterioration

d Rate of deterioration/prediction future condition

e Predict future LCC

f Cause/extent of deterioration

g Traffic delays

hOptimal maintenance methodi Decide maintenance strategy

jOptimal maintenance programme

Prioritization model

Implication model

Comparison model Budget variation model


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VI. THE FRAMEWORK OUTPUTS

In direct correspondence with the previous

chapter, here-bellow is presented the

frameworks outputs, with the mention that the

values in parenthesis represent the outputs for

the network level BMS, the first (from 1 to 11)

being the outputs for the project level of a BMS.

1 Current condition state (elements)

2 Current condition state (bridge)

3 Original LCC and Critical areas

4

Condition state/time trajectory for eachelement

5 Condition state/time trajectory for bridge

6 Date for essential maintenance

7 Cause/extent of deterioration



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8 Delay costs due to maintenance or restrictions9 Optimum maintenance method

10 Best maintenance strategy

11 Optimal maintenance programme(12) Prioritized maintenance programme

(13) Values of policy parameters

(14) Degree of compliance with policyparameter targets

(15) Budget needed to obtain say 90%

compliance

From Table 1 one can easily read any inputs that

are associated with a specific output.

Remembering the fact that some of the outputs

can play the role of derived inputs, i.e. some of theoutputs are inputs themselves for different models

(or calculations) and generate other outputs, theFigure 1 can be rearranged in a more synthetic

fashion as in Table 1.


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OUTPUT DERIVED INPUTS BASIC INPUTS

1 A,B,C

2 1

3 A

4 D

5 E

6 3,4 F

7 B,C

8 6 G,H

9 7,8,10 A,I,J

10 1,3,4,6,8 A,K,L

11 4,3,8,9,7,6 A,J,K,M

(12) 11 N

(13) (12)

(14) (13) O

(15) (14)

TABLE I. INPUTS

ASSOCIATED WITH OUTPUTS(SEE FIGURE 1)


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CONCLUSIONSThe key point of this paper is that a computerised

Bridge Management System can be createdstarting from the main activities of management

such as, maintenance, inspections, technical

expertise, testing, etc.

The analyses was conducted respecting the two

levels of management, i.e. the project level

(dealing with specific, particular bridges) and the

network level (dealing with a whole pile of bridges).

This framework was developed as a result of acomparative analysis of the European BridgeManagement Systems that are in force nowadays

and is the proposal of the BRIME committee for a

unified management system.



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CONCLUSIONSRomania has to implement a Bridge Management

System of this kind that must comply, notnecessarily in its entirety, with the general

architecture of this European BMS and also

incorporate the supplementary constraints of our

technical norms in force.

The advantages of having o fully operational BMS is

that the managers are aided in their decisions by a

systemized and computerised tool that can help

them find answers to a variety of questions, one of

the most important one being the prediction

question what if... ?.

This kind of management system can be further on

developed to be intergrated into a more complex

one: a inter-connected Pavement Management

System with a Bridge Management System.



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The General Architecture of a European Bridge Management

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