Project Information

The NAU Challenge Course Climbing Wall project was proposed by NAU, will be designed by a Civil Engineering Capstone team, and will be constructed by the Construction Management Program.  The design and construction will be completed by students for no charge to NAU.  NAU has asked that the structure be designed to the standards of The Association for Challenge Course Technology (ACCT), but indicated that engineering codes supersede ACCT standards.

The key stakeholder in this project is NAU Campus Recreations.  NAU will be providing the funds to pay for the building materials, professional engineer’s approval, and any subcontracting that is required. Other stakeholders include NAU faculty and students and other businesses or groups utilizing the climbing wall.

Project Constraints

• Wall must be 12 feet high and 8 feet wide
• Must use two wooden cedar poles as main support
• Poles must be installed into the ground at a depth of 4 feet, or 10% of their length plus 2 additional feet, whichever is the greater of the two
• Trex Deck must be used on front face of wall
• Must have a platform on the backside 9 feet above the ground level
• A belay cable must be installed at least 1 foot below the top of the poles
• No guy wires are to be utalized in design
• Use availabe materials

Design Alternatives

As shown below, a decision matrix was created in order to determine which type of deck support to use in the design. The options include a truss supported deck, which are two diagonal pieces of sawn lumber supporting the deck, or a post supported deck, which are two vertical posts that bolt into a shallow foundation on the ground surface.

The design chosen was the truss supported deck due to the fact that it is more economical, has better aesthetics, and is significantly easier to build than the post supported deck.

Origionally, NAU had asked the Capstone team not to use polyurethane expansion foam for the foundation due to issues that had occured during construction of the Challenge Course. In order to determine what material would work best for the foundation, another decision matrix was created, as shown below.

After reviewing the results of the decision matrix, it was determined that polyurethane expansion foam should be used. The construction team would need proper training to learn how to properly mix and place the foam into the boring.

Details of Final Design

Geotechnical

Previous geotechnical studies indicate solid rock just below the ground surface.  The rock will be excavated for placement of the two structural poles at a depth and width complying with ACCT code.  Once the poles are placed, the remaining space within the holes will be filled with polyurethane expansion foam which will work as the foundation for the wall.  The rock presents a solid foundation for the poles; however, strength of the rock was be determined to ensure it has the strength required support the wall and applied loads.

Loads

Designing the wall itself required an in-depth look at the structural demands the wall will receive. Wind and live loads will be the largest forces acting on the structure, and therefore the team’s biggest concern.  Load magnitudes were estimated using the ASCE 7-05 (Minimum Design Loads for Buildings and Other Structures) as a guide, and using LRFD (Load and Resistance Factor Design) load combinations to ensure conservative loading cases.  These estimates were then checked to ensure compliance with the City of Flagstaff standards.  Calculations must be completed to insure that the wall is capable of withstanding wind and live loads as well as self-weight and snow loads, with a built in factor of safety from the LRFD calculations.  Safety is one of the Capstone team’s biggest concerns and is vital to the project, so all calculations are conservative.

The Final Design

The rough design, shown to the right, uses two wooden poles as supports for the structure with the base of the poles placed into the bedrock.  All dimensions were determined according to NAU’s design criteria.  The face of the wall is composed of a frame with Trex deck running vertically (to keep the wall face from being used like a ladder).  Horizontal supports run across the back of the frame (according to the International Building Code, IBC) and a diagonal support will be added to resist swaying.  The back deck is run between the two poles and will be attached to the poles with both horizontal and angled supports in order to create a small truss.  A railing was added to the deck according to IBC code.  A removable ladder will be purchased by NAU for entry and exit from the deck.

Final Auto CAD drawing located under the "Documents Tab."

Materials

The materials to be used will include Trex Deck Lumber and 12 inch diameter Western Red cedar poles (class 3), as specified by NAU.  All other materials were determined by the design team according to available resources and safety of design. Any spare poles, decking, bolts, and harness tie-ins will be used for the construction of the wall.

Schedule and Team Budget

Schedule

Team Budget