**6.3 Prevention and protection**

Since material degradation process is inevitable for both physical and environmental factors, a few actions must be considered on the design process to control

**Figure 21.** *Bridge concrete construction joint damaged [20].*

**Figure 22.** *Steel beam with fatigue crack failure [21].*

*Bridges: Structures and Materials, Ancient and Modern DOI: http://dx.doi.org/10.5772/intechopen.90718*

#### **Figure 23.** *Steel beam with fatigue crack failure [23].*

due poor construction procedures. **Figure 21** shows a typical bump problem, which can be avoided using any joint procedure and materials offered in the industry.

notice there are no yielded zones on the beam, only a sudden crack.

**6.3 Prevention and protection**

*Infrastructure Management and Construction*

**Figure 21.**

**Figure 22.**

**114**

*Bridge concrete construction joint damaged [20].*

*Steel beam with fatigue crack failure [21].*

Another physical factor that affects the structure is fatigue, caused by the loading and unloading forces due the traffic flow, affecting the stressed elements of the bridge. Fatigue causes degradation on material mechanical properties with each load cycle; this means each vehicle passing over the deck. If each cyclic load produces a stress equal or higher to yielding stress of the material, therefore a large amount of cycles will cause a decrease on the material allowable, allowing brittle failure of the element. **Figure 22** shows a crack developed due fatigue stress loads;

Since material degradation process is inevitable for both physical and environmental factors, a few actions must be considered on the design process to control

corrosion, wear and fatigue. Prevention and protection procedures are required, including maintenance process to avoid possible damage.

Corrosion prevention is the best economic way to preserve the structural elements of any bridge and the result is a positive benefit in the useful life of the materials [22]. Acidic corrosive emissions and hydrocarbons, in combination with high humidity accelerate the process of corrosion and degradation. The designer should analyze the type of electrochemical attack that would occur during the life of the structure.

For structural steel, epoxy paints are used to insulate direct contact of water or moisture. For the reinforcement of concrete, should take care of the coating to avoid exposure to moisture. As shown in **Figure 23**, the possibility of install a cathodic protection system should be considered.

Wear degradation process is unavoidable for any surface subjected to friction; therefore, the damage depends of the applied load and affected zone. If a flexible roadway is used, wear degradation is higher and requires additional maintenance compared with reinforced concrete roadway. By the other hand, reinforced concrete piers may have contact with the water flow of the river; frictional forces would be present and wear factor became an issue, requiring additional coating to protect the reinforcing bars.

For fatigue degradation process, the designer must consider the weight of all vehicle types, cyclic loads, loading scenarios and fatigue material properties as a way to prevent brittle failure. All elements should have enough stiffness to avoid high stresses under typical cyclic load cases, therefore the fatigue allowable stress should be greater than the applied loads. Fatigue procedures as Modified Goodman Diagram or Miner's Rule are used [24].
