The IAP 11 It serves as a set of instructions and guidelines for the design of bridge projects based on the loads they are designed to withstand. It covers how to quantify loads, dimension structural members, and apply design assumptions from the perspective of functionality and structural safety.
Compliance with this Instruction is a necessary condition for authorizing the crossing of other roads over the roads of the Spanish National Highway Network.
IAP 11: Purpose and Scope of Application
The education and IAP Guide 11 focuses its study on all infrastructures known as cross-passage works (ODP) that support the roads. One ODP It is considered to be one that allows for both the circumvention of discontinuities in the route and the avoidance of topographic features or other civil engineering structures.
The purpose of this guideline is to establish common design parameters and methodology for culverts:
- Determine the actions to be taken.
- Calculating Weighting Coefficients.
- Specification of Action Combinations in a Project.
- Functional criteria.
General Design Principles
Below, we briefly explain the general principles that serve as the basis for calculating loads on highway bridges in accordance with this instruction.
Essential Requirements
For the proper functioning of the infrastructure Throughout its service life, the following fundamental requirements must be met.
- The team of design engineers must consist of qualified professionals with sufficient experience.
- The team of technicians and operators responsible for carrying out the work must have the necessary knowledge and experience.
- The building materials that will comply with the technical requirements established by regulations.
- Quality controls will be carried out throughout the entire project and implementation process.
- The structure will be used for the same purpose for which it was designed.
Service life
The service life of a bridge is the period of time during which it will serve to fulfill the functional and safety tasks for which it was designed, starting from the end of its implementation.
- Estimated 100-year design life for highway bridges.
- This includes its upkeep and maintenance.
- It does not include significant renovation projects.
Verification Criteria
The structural strength It must allow for functional and safe use. These characteristics will be verified by comparing the stabilizing forces of the structure and the ground, which must be higher than the destabilizing values.
Destabilizing forces result from external loads acting on the structure, and they are calculated at the ultimate limit state corresponding to the design scenario to be analyzed, including the appropriate safety factors.
Ed,dst ≤ Ed,sbt
- Ed, etc. calculated value of the effect of destabilizing actions
- Ed, sbt calculated value of the effect of stabilizing actions
Project Scenarios
The project scenarios These are physical conditions that could affect the structural safety of the bridge. Each project must conduct an individual assessment of potential situations that could affect the bridge during its service life, taking the following into account.
- Conditions that persist throughout their service life.
- Temporary situations during periods such as construction or repair.
- Accidental or exceptional situations, such as a vehicle collision.
- Seismic events under exceptional conditions.
Borderline States
The borderline states These indicate the maximum stress condition that each structure can withstand according to the established design criteria. For the purposes of applying this Instruction, they are classified as ultimate limit states and serviceability limit states.
Ultimate Limit States (ULS)
The Latest Border States refer to the maximum stress that the structure, or any of its components, can withstand before structural failure. The instruction considers the following:
- Equilibrium ELU (EQU): loss of static stability.
- Stress-Strain Limit (STR): Resistant failure or excessive plastic deformation.
- Fatigue ELU (FAT): a result of repeated variable loads.
Service Limit States (ELS)
The Service Limits refers to the maximum load that the structure can withstand while maintaining the functional or service conditions for which it was designed. The instruction considers the following:
- Cracking-related ELS: affects the durability or appearance of the bridge.
- Deformation-related structural damage: affects the appearance or functionality of non-structural elements.
- Vibration ELS: those exceeding the levels considered acceptable for user comfort.
- Laminating-related ELS: irreversible damage or deformation.
- Slip ELS: affects joints secured with high-strength screws
In conclusion, the IAP 11 is an excellent guide—comprehensive and easy to follow, which allows for the drafting of ODP projects for roads within a mandatory regulatory framework.
