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“REI’s U.K. office developed the ‘bridge loader’ extension for STAAD.Pro to minimize the load application process, while complying with U.S. and international code requirements,” he said. The current version of BEAVA supports U.S. AASHTO 2000 standards and U.K. BS5400 Part 2 code. Eight international engineering firms collaborated with REI to develop the software.
The general philosophy governing bridge design is that, subject to a set of loading rules and constraints, the critical effects due to load application should be established and designed for. The process of load application can be complex since governing rules can impose interdependent parameters such as loaded length on a lane, lane factors and load intensity.
To obtain the maximum design effects, engineers have to try many loading situations on a trial and error basis. This leads to the generation of many live load application instances that have to be combined with dead load effects as well.
The bridge loader application is based on the use of 3-D influence surfaces, which are generated by STAAD.Pro as part of the loading process. An influence surface for a given effect on a bridge deck relates its value to movement of a unit load over a particular point on the bridge deck.
The program will automatically generate and draw influence surfaces for effects such as bending moments on members, support reactions, element stresses and deflection nodes. The engineer can then instruct the program to use the relevant influence surfaces and optimize load positions to obtain the maximum desired effects
After BEAVA generates the influence surfaces, the program saves them and they can be reused for any further investigation that may be required. The program can then proceed to follow the selected design code and calculate the number of traffic lanes, influence lines along the centerline of the traffic lanes, loaded length along the lanes, critical locations of all knife, UDL and vehicular loads, and the maximum and associate effect values. All results are displayed graphically including the critical position of the vehicle along the traffic lanes.
“The engineer’s knowledge and judgement is critical in deciding which effects and at what position on the bridge deck to obtain them,” Das said. “This is where users of the program can save a lot of processing time, and also can ensure critical positions are not missed.”
All relevant code instructions for loading definitions and traffic lane calculations are incorporated in BEAVA, and in cases where vehicle axle arrangements are not standard, it is possible to define a vehicle and save it in the library for future analyses.
BEAVA is fully integrated in STAAD.Pro and uses the same interface (GUI) for all input and output data. Loading arrangements can be displayed on the model, and for every loading arrangement produced, the user can instruct the program to generate a STAAD.Pro load case. The added live load cases can be subsequently combined with dead loads (non-moving vehicles) using STAAD.Pro load combinations. The final model can then be analyzed in STAAD.Pro. In addition, BEAVA also supports curved bridge roadways.
REI announced release of BEAVA at the company’s 15th Annual STAAD Users Conference in Las Vegas, Nevada, attended by DOT representatives from throughout the U.S. and engineers across the globe.
Research Engineers International, a division of netGuru, Inc., is a leading worldwide developer and distributor of high quality desktop and Web-enabled software solutions for the engineering industry. Founded in 1981, the company’s core business is the development of cost-effective, Windows-based solutions. REI has nearly 19,000 customers accounting for over 47,000 software installations and 140,000 concurrent users worldwide. Please visit REI’s website at www.reiworld.com.
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