Bridge building, especially when the bridge must span massive distances and withstand tons of traffic, the possibility of earthquakes, high winds and other tests of strength and design, requires both art and science.
The art and science of designing and building bridges have changed for the better as a result of increased understanding of engineering principles, as well as advances in technology. New materials and methodologies add to the changes in bridge building.
One of the newer methodologies that are widely used in building bridges and other structures is 3D modeling – specifically as it pertains to structural analysis.
Structural analysis is the determination of the effects of loads on physical structures and their components. Structures subject to this type of analysis include all that must withstand loads, such as buildings, bridges, vehicles, machinery, furniture, attire, soil strata, prostheses, and biological tissue.
Structural analysis is combined with computational engineering to develop and apply models and simulations to solve the complex physical problems that arise when designing and engineering structures such as bridges. Computational engineering uses 3D model simulations for both the conceptual and design development phases.
Initially, computational engineering can be used to quickly investigate the best forms and geometrical options for the structure. The process can be used to refine and economize the design, aiding the design engineers in understanding the structural behavior, visual appearance, fabrication complexities, and sustainability issues.
The ability to produce early 3D images and renderings is important. 3D images help to solidify the design and provide virtual models for clients and stakeholders. By controlling parametric boundaries, it is possible to quickly optimize the design for a number of parameters ranging from weight to solar heat gain, offering early evaluations of issues such as constructability or energy modeling.
Once the overall design concept is agreed upon, the structural analysis provides the numerical mathematical process to extract structure responses under service and seismic loads in terms of structural demands such as member forces and deformations.
Some of the structural analysis tests that might be run include these adapted from the CalTrans Bridge Design Practices, February 2015:
- Static Equilibrium
In a supported structure system when the external forces are in balance with the internal forces, or stresses, which exactly counteract the loads (Newton’s Second Law), the structure is said to be in equilibrium.
- Dynamic Equilibrium
When dynamic effects need to be included, whether for calculating the dynamic response to a time-varying load or for analyzing the propagation of waves in a structure, the proper inertia terms shall be considered for analyzing the dynamic equilibrium
- Vibration Analysis
Vehicles such as trucks and trains passing bridges at a certain speed will cause dynamic effects that must be analyzed.
Designing, engineering, analyzing and testing can all be done via 3D CAD techniques. These techniques enable better structures, faster, at lower costs. For more on how CAD / CAM services can help, contact us, or learn more about our 3D CAD conversion services.