Progress Report 8

The mechanism calculations were performed and a custom motor is required to satisfy the low speed and high torque requirements of the bridge. The mechanical parts and results comply with AASHTO standards for a safe and efficient bridge design. A final cost analysis is compiled for the new projected cost of the full sized bridge. This is based on the final cost of all members and the estimated cost of the mechanical parts, construction, and other necessary labor and parts for the pedestrian bridge.

Progress Report 7

Modal analysis was performed on the bridge in ANSYS APDL with frequency results above 3 Hz, which is an AASHTO requirement. The first mode is shown in the figure with a fundamental frequency of 4.46. This frequency guarantee that the bridge will not collapse due to resonance with the natural frequency.

This finalized the original member selection and member connection designs are being calculated for each connection of the truss.

Progress Report 6

The Visual Analysis model of the bridge has been created, as shown in the first figure. This model was used to select beams in groupings. The beams selected were W6x15, W6x12, W8x24 beams of ASTM A992 Grade 50 steel based on the minimal deflections of the bridge in the closed and open positions as shown. This model is being imported into ANSYS where vibrational analysis can take place.

The prototype of the center mechanism is complete and features two motors, two gear boxes, two gears, one rack, six balance wheels and one switch to control the prototype in neutral, forward, and reverse.

Progress Report 5

This semester, one of the parts being worked on is the prototype. The rack and track have been 3D printed and all of the parts have either been ordered or have arrived. The assembling of the prototype will happen in the next few weeks. An abstract for a paper/poster presentation for the ASME International Undergraduate Research and Design Expo has been submitted for review. Upon approval the team will make a presentation at the conference outlining specifically the ANSYS validation of the truss model. The loading combinations determination and member selection are ongoing and will help the team to then move on and create their final ANSYS model with the final members. The Visual Analysis model is being created now using the loading combinations to determine the size of all members on the truss.

Progress Report 4

We have successfully copied the results of the validated ANSYS article in our own ANSYS analysis. Our results are shown here and display that the frequencies found from our model are close to the ones found in the article. We are continuing to adjust our model, including changing the boundary conditions, the density of each material, and other aspects not specified in the article to get closer results. Once we are satisfied with our results, we will begin altering this model to match our truss design (also shown below).

We are continuing to test load combinations to verify the main forces acting on the bridge. We are also working on the calculations for the preliminary mechanism design using an initial weight similar to the one being used for the actual Grays Ferry Pedestrian Bridge. Since we are not able to find an accurate weight of our bridge until we have calculated all of the load combinations, this weight will serve as a good estimate for initial calculations.

ansys results website

Mode Article Results (Hz) ANSYS Results (Hz)
1 4.80 4.04
2 6.13 5.94
3 8.33 10.85
4 12.29 11.28
5 13.40 13.17
6 18.80 15.21

truss

Progress Report 3

Our team went on a site visit on October 5 to learn more about about the current Grays Ferry Bridge and the ongoing pedestrian bridge replacement project. We met with Lane Fike, PE ; the Director of Capitol Programs at SRDC, Joseph Syrnick; President and CEO of SRDC, and Joseph Sullivan of Louis Berger. We discussed the existing bridge and its mechanical and structural attributes, as well as the designs for the replacement pedestrian bridge. We also discussed realistic constraints such as the historic eligibility of the bridge and the necessity of the bridge to be a movable one. We compared some of the AASHTO standards and recommendations, such as pedestrian and vehicle loading, to their ideas and were able to determine what type of constraints and abilities the bridge should have.

Since our last progress report, we have begun determining the amount of live loading that our bridge will experience for our preliminary design. We have also begun designing the truss and decking system to determine the total dead load of the bridge. This dead load will be used for calculations for our first design of the mechanical equipment. We have also created a preliminary model on Solidworks that serves to only show the layout of how the mechanical parts will work together and how they will attach to the span.

Scholarly articles and case studies for vibrational analysis for truss swing bridges have been studied and one has been chosen to be duplicated. The article chosen is “HUMAN COMFORT ANALYSIS AND VIBRATION CONTROL OF A STEEL-CONCRETE COMPOSITE FOOTBRIDGE” written by Joesley P. Mendes , José Guilherme S. da Silva and Wendell D. Varela. It is an analysis of the kinds of vibration and modes of vibration that a pedestrian truss bridge experiences. We will be copying their study and matching their results. Once the end conditions and modes of vibration are verified, we can build upon the geometry to create our specific bridge design.

Progress Report 2

This month, we have been researching, contacting companies, studying preliminary designs, and beginning to experiment with designs in ANSYS.

We have researched the specific type of bridge we are designing: center bearing pedestrian swing bridge. We have researched the existing Gray’s Ferry Swing Bridge, its mechanisms and shortcomings. We have also researched the plans for the new pedestrian bridge in its spot. We have also found scholarly articles from ASCE and other databases that explain the process, design, and results of verified swing bridge designs. These designs will be used as a basis for our design; we will create them in ANSYS to achieve the same results as in the article. These validated results will be built off of, so that there is confidence that our bridge design, created off of their bridge design, is also validated correctly.

We contacted SRDC (Schuylkill River Development Corporation), Hardesty & Hanover, and Louis Berger to set up a site visit. We will be meeting with representatives, professional engineers and CEO’s from these companies at the Gray’s Ferry Bridge construction site on Wednesday, October 5. We have done preliminary research and calculations based on this bridge that we will compare to their design and request more input on how to make an ideal design for our bridge.

We have studied the existing Gray’s Ferry Bridge designs, given to us by SRDC, to study the basic mechanisms that go into designing a center bearing swing bridge. We have begun experimenting with ANSYS to create simple designs to aid in our process once our designs have been decided on.

Progress Report 1

Preliminary research on different types of movable bridges and possible bridge locations was done throughout the summer. In September, it was chosen to redesign the Gray’s Ferry abandoned rail swing bridge over the Schuylkill River in Pennsylvania, Philadelphia. Research is being done on the types of mechanisms needed, the traffic across the bridge, and the environment and weather of the area. Research has also been done on how this bridge will be validated without a full moving prototype. ANSYS has been tested by the team members and optimal methods for creating a correct, verifiable geometry have been studied.  A trip to visit the site with the companies working on the new bridge is scheduled for next week. We have also obtained drawings and specifications for the current bridge to assist in beginning our design. We are currently studying the codes required for movable and pedestrian bridges and are deciding on an optimal design to fit the constraints due to the environment and the type of bridge.

Gray’s Ferry Swing Bridge Redesign

14595535_10153827118341850_5483250654282835388_nThe Gray’s Ferry Swing Bridge Redesign Project is a software redesign of the existing abandoned rail swing bridge over the Schuylkill River in Philadelphia, Pennsylvania. The current bridge, located next to the Gray’s Ferry Avenue Highway Bridge, is unusable because the railroad has been rerouted across another part of the river. The goal of this redesign is to create a pedestrian bridge, using the current foundation and center pier, that will be a continuation of the pedestrian trail connecting both sides of the river that is currently in progress on one side of the river. This bridge is eligible to be historic, so certain measures must be taken the mitigate the impact of this construction on the historic bridge. Some or all of the truss must be salvaged and used for the public and the new trusses must look similar to the old ones.

Our senior project team of two mechanical engineers and one civil engineer will research, design, model, and validate the most optimal redesign of this bridge to create a usable, efficient, and safe design. Using CAD software to model bridge parts, ANSYS to validate the loading and kinematics, Visual Analysis to design the members, and working prototypes of mechanisms to display the kinematics, the team will validate the geometry, loads, vibrations, materials, and movable aspects of the bridge, without creating a scale model of the bridge. Creating a scale model would deviate from how bridge design is done in industry, where designs are created and validated, then immediately turn over to the construction phase. The goal of our project is to design a bridge as it would be designed in industry. SRDC, Louis Berger, and Hardesty & Hanover are currently designing a replacement pedestrian swing bridge for this existing bridge and representatives from each company have agreed to advise us throughout our senior project.