Webber and LAN Build Newest Galveston Cruise Terminal Upon Unique Foundation
Adding terminal capacity to one of the busiest cruise ports in the country in Galveston, a design-build team created a $12.7 million terminal addition that rests on the foundation of an 1930s-era grain silo, a blend of new and old that works for the port.
"We are proud we were able to develop a creative foundation solution, which required support from the entire design-build team," says Jon D. Jelinek, an Associate with Lockwood, Andrews & Newnam (LAN) in Houston and structural engineer of record.
The Port of Galveston handles more than one million cruise passengers a year and is the fourth busiest cruise port in the nation. It ranks among the top 10 in the world. The original buildings were cargo facilities, for cotton and other products exported by Texas. They were retrofitted to basic facilities to operate as cruise terminals years ago.
"The market has grown and the cruise line said it wanted to bring in a larger vessel with more capacity," says Bruno Elias Ramos, AIA, Principal In Charge for BEA Architects in Miami. "But in order to do that, it needed facilities that can process passengers more efficiently."
The team renovated the old terminal and built a new structure, linking the two with a connector building.
"The new facility has all of the amenities," Ramos says. "It can handle the larger vessels."
The new 60,000-square-foot terminal will provide seating for more than 2,500 passengers. Scope includes building a larger security screening area, waiting areas and ticket counters.
"The check-in process minimizes stops and hurdles and maximizes the number of passengers who can be debarked and embarked," Ramos explains.
Webber of Houston received the design-build contract to expand Cruise Terminal No. 2 to accommodate more passengers and larger ships in 2014. The port used a qualification-based, two-step process, with a technical and price proposal.
"It was a team effort, with everyone working well together," says Casey McKay, Project Manager for Webber.
Webber started excavation and concrete plinth work in October 2015. The first floor slab was poured and steel erection began in January.
Soil Conditions Present Challenges
Originally, the plan was to build a new building in a different location. But a large portion of the site had poor soil conditions, a 17-foot-deep layer of soft clay, which was susceptible to consolidation and settlement. It became a major hurdle. To accommodate flood plain requirements, the finished ground floor elevation was established 6 to 8 feet above existing grade. The load associated with the fill overburden would impose intolerable settlements that forced the team to consider an alternate building configuration and foundation.
"When you have roughly 30,000 square feet of surface, 90 percent used for pedestrian traffic, we could not have trip hazards that might result at the expansion joints," McKay explains. Ramos and the team at BEA had to reconfigure the building layout so it fell within the footprint of a pair of old grain silos' mat concrete foundations, and Webber's design team had to ensure it would support the new building.
"We found ourselves in a predicament that stifled the project, but the solution, with innovation on the design side and getting the client buy in, was the best for the project," says Kyle Rodemacher, Webber's Design Manager.
Horner & Wyatt, industrial engineers in Kansas City, Missouri, designed the grain elevator foundation more than 80 years ago. The 40-foot thick reinforced concrete mat was supported by more than 4,000 12-inch diameter, 30-foot long timber piles spaced at 2.5 feet on center each way. The former grain silos, removed in the 1990s, had been more than 100 feet tall. LAN performed some core sampling and visualized the timber piles, completed a structural analysis.
Webber had to excavate down between 7 and 8 feet to make the old mat visible. The team demolished a portion of the mat to expose the butt end of some of the timber piles to visualize their condition and to facilitate nondestructive pile integrity testing. Concrete core samples were retrieved and tested for compressive strength.
"By exposing the piles, we could see they were on plan," McKay says. "They were incredibly well preserved. There was no deterioration at all. It was pretty impressive."
The timbers had been submerged below the ground water table, which helped to preserve them. The team conducted finite element modeling to determine settlement contours. LAN was then able to conclude the mat foundations were sound and capable of holding the new structure's surcharge loads, which were transferred to the mat slabs, 13-feet below the floor of the new building.
Using a 1930s-era grain elevator foundation for the new building, became very important to the success of the project," Jelinek says.
"Once we got the permits, the construction has gone well and quickly, and that was because of the collaboration," McKay says.
The team brought in fill material having suitable properties to accommodate a soil-supported ground floor slab. The thickness of the fill material varied between 6 and 8 feet to establish the desired finished floor elevation above the 100-year flood plain elevation.
Webber self-performed the dirt work and concrete, except for pouring the main building slab. Demac & Company Concrete Contractors of Houston poured the slab.
The two-story pre-engineered metal building was designed to withstand hurricane-force wind speeds of 140 mph. LAN designed concrete closure walls around the perimeter to accommodate hurricane-force winds and storm surge effects. All loads are collected into the concrete plinths, which are anchored into the robust silo mat foundations.
"We were able to capitalize on the economic efficiency of a pre-engineered metal building," Rodemacher says. "By nature, the metal buildings are flexible. With the relocation to a freestanding facility, rather than the original location that interfaced with the existing terminal, we were able to let the metal building move more freely."
Ramco Erectors of Houston erected the structural steel, and the building came from Rigid Global Buildings in Houston. JW Kelso Co. of Galveston handled the interior build out, which includes a ramp so passengers can roll their carry-on baggage instead of using the escalator, improving the disembarking process.
A two-level connector building links the old and new terminal. It is structurally separate from the new building and features a structured ground floor, mitigating the effect of the poor soil. The connector building is founded on spread footings.
"By limiting the bearing pressures of our foundations to less than 1,000 pounds per square foot, it did not reduce the capacity of the existing building's foundations," Jelinek says.
All of the construction took place while the original terminal continued to serve passengers. At times, construction activity had to stop when cruise ships were in port.
The team had zero recordable injuries. On most days 100 people were working on site. Several engineers and safety managers monitored activities. The team is proud of the safety record and completed the project in June.
"It's been a successful project," McKay says. "It's truly been a great team effort and project."