By Jenee D. White
AECnews Contributing Writer
The tragedy of the August 1, 2007 collapse of Minnesota’s I-35 W. Mississippi River Bridge raised red flags around the nation, and became a focal point for the construction of top-performing, safe bridges. Preventative measures will depend on greater information about material strengths, the effects of various forces, and outcomes of damaging events like earthquakes and massive storms.
Though the exact cause of the bridge collapse has yet to be determined by the National Transportation Safety Board, it is believed that possible errors in the initial 1967 construction may have caused or contributed to the failure. This eight-lane steel truss arch bridged the Mississippi River in Minneapolis. Maintained by the Minnesota Department of Transportation (MnDOT), it was Minnesota’s fifth busiest bridge, averaging 140,000 vehicles daily; it was initially designed to carry only 66,000 vehicles per day.
Currently in the planning phase of bridge replacement, MnDOT will build St. Anthony Falls (35W) Bridge using the technological advancements of today’s bridge solutions, providing a means for improved constructibility, structure performance, and maintenance of traffic.
Bridge design and engineering software automates the design of bridges, giving engineers the means to perform an array of sophisticated analyses of the design. More importantly, they can simulate the performance of bridges and give engineers the opportunity to investigate virtually unlimited designs to arrive at the best possible one.
Bentley Systems has taken a keen interest in the Minnesota tragedy and what it means to bridge engineering in general. In addition to creating software for design and engineering, Bentley provides tools for monitoring the conditions of bridges, such as the company’s LARS/BridgeModeler products. Complimentary 3D laser scanning technology allows for data collection of structures, providing a better understanding about existing bridges, many of which were built long ago.
Bentley Bridge RM software provides a solution for complex bridge design, which provides linear and non-linear structural analysis. The software has the ability to analyze 3D bridge systems of any type. The software can accurately check the bridge for stability and serviceability. RM includes load analysis for reinforced and pre-stressed members, shear checking, and more, and can determine if and where additional reinforcement to a bridge structure is needed.
Engineers are able to analyze how weather conditions will affect the design and mitigate the effects of possible events via RM’s computational fluid dynamics and wind testing capabilities. Specialized RM applications include analysis of rolling stock to understand and minimize vibrations and other effects from carrying high speed trains.
Construction of a bridge is a major effort that must be meticulously planned. The RM system includes the ability to study a fourth “time" dimension that simulates in 3D the performance of the bridge components under construction. This allows analysis of how the bridge-in-progress will react during the various stages of construction.
Bentley has a particular vested interest in the bridge industry, as it offers solutions that span the bridge lifecycle, to include the company’s focus on bridge information modeling (BrIM). BrIM is an approach intended to enable delivery of safer, better-engineered bridges , as well as a means to process innovation in bridge construction, maintenance, operation, and rehabilitation.
The W9 Almbrücke Bridge in Austria was recently built using Bentley structural analysis software. It is a continuous beam over five spans. The cross section is a composite construction of steel box girder with concrete slab, for a total length of 264 meters.
Engineering Software to secure construction of roads and buildings
A data sprawl exists in today’s construction of transportation and commercial infrastructures. The inability to gather and access the important data relevant to one’s task is debilitating, which not only costs time and money, but introduces unnecessary risk. Data is held in “silos” of information; often, key software and data systems do not interoperate or share data effectively. Certainly stakeholders in the process are frustrated when attempting to collaborate with one another.
Bentley offers a number of data sharing, collaboration and project management tools, such as ProjectWise, which enable vast sharing of the “right,” most timely engineering data across an organization. The system goes beyond document management to address version control, digital signatures, workflow access, data security, and more.
Information of a structure is gathered from the beginning stages of design, and is continuously added to until the structure’s decommissioning. This information is critical to planning and design for better security and sustainability, which provides an historical view that enhances planning for the future.