deep trellised wood-decked overhangs. Lake|Flato’s concept designs show the columns terminating at the bottom of wide-flange girders. Options were reviewed, including one making the column and beam centroids coincident, but the team determined that the visual effect was not as dramatic. In keeping with the exposed structures elsewhere in the museum, Datum recommended introducing offset steel tie rods to take the thrust from the columns. Further study on the wood columns proved a glued-laminated, tapered member to be ideal. Due to the proximity of museum visitors, the connection detailing here was even more critical than the Great Hall trusses, and Datum’s engineers worked closely with Lake|Flato to provide clean knife-plate reinforced pin connections. The Witte Museum has always been a cultural anchor for San Antonio, but the reimagined spaces have put it on par with the top-caliber natu- ral history museums in the country. Kim Biffle, chief of engagement at the Witte, said that the city and local residents have shown a new level of pride and ownership in their museum. This is evidenced in the increased attendance and consistent flow of requests for the banquet spaces and courtyards. Furthermore, the new spaces are allowing the Witte to host the premier event of a changing exhibit for the first time in the museum’s history, and to be the centerpiece of exhibits for “Confluence in Culture,” an exhibit showcasing 300 years of history coinciding with San Antonio’s upcoming tricentennial. The team wanted to incorporate wood into the Susan Naylor Center’s exposed structural elements, resulting in glue-laminated heavy timber roof decking over steel beams and tapered glue-laminated wood king-post roof trusses.
Part of the existing structural system included clay-tile formed ribbed concrete floors.
team wanted to incorporate wood into the exposed structural elements, resulting in glue-laminated heavy timber roof decking over steel beams and tapered glue-laminated wood king-post roof trusses. Also, similar to the changing exhibits building, the top chord member is a pair of steel channels to conceal electrical and fire sprinkler conduit, with steel rod tension chord and bridging. The final truss connection detailing may look simple, but it is the result of a number of cycles of suggested and tested arrangements. Additional second-floor framing along the east façade was necessary, in part to help the Witte showcase a larger portion of its collection of several hundred donated Fiesta royalty gowns from San Antonio’s annual Battle of Flowers parade. That floor framing was executed in composite steel with varying specifications of architecturally exposed structural steel. To match the existing construction and reduce the im- pact of expansive soils, the ground floor system was designed as a two- way concrete slab, cast on cardboard forms and resting on belled piers. The addition wraps around and into the west courtyard, where it transi- tions into a two-story screened porch enveloping an ancient Cypress tree. The team crafted designs for a wood-decked steel roof, a com- posite steel second floor, and a ground floor framing of heavy timber decking on steel beams around the tree’s trunk. At the foundation, the team’s precautionary measures for the tree included exposing the near- surface roots during construction and obtaining an arborist’s opinion of acceptable excavations. Following those guidelines, the drawings were revised, moving a new pier further from the tree, shallowing up the perimeter concrete and steel floor beams, and cantilevering over larger roots. For the approach to the building from the south, and also for the entry into the great hall from Broadway Street and from the Witte’s west courtyard, something special was in order. For these three entries, the design team wanted to introduce V-shaped pairs of wood columns with
LARRY RICKELS, P.E. , served as principal in charge of the structural team and managed the renovations to the existing structures for Datum Engineers Inc. (www.datumengineers.com); Datum’s TIM STOCKS, P.E. , managed the enhance- ments to the Susan Naylor Center; and CRAIG RIOS, P.E. , president of Datum Rios, managed the structural designs for the Mays Family Center.
29
april 2018
csengineermag.com
Made with FlippingBook Annual report