Tanglewood Embassy Suites Solarium

The Project

The Tanglewood Berkeley Heights Solarium project consists of a one-story 2,200 SF, enclosure constructed adjacent to a 150,000 SF nine-story hotel. The Solarium was designed using curved, built-up steel bent frames that support a high steel cupola. Auto-dimming Sage Glass clads the conservatory exterior, which changes translucency when positive current is applied. Ehlert Bryan was the Engineer of Record for the main hotel building and for the Solarium structure.

Structural Features

The Solarium’s structural system consists of four main, varying depth, curved steel frames containing multiple size openings that span unbraced through the clearstory. A continuous tension ring resists outward thrust at the low roof eave. Varying depth steel hip and leaner frames connect into the main frames to create the rectangular tiered open volume. Due to sequencing issues during construction, lateral loads were resolved using cantilevered wide flange steel columns fixed to the hotel foundation walls in lieu of the hotel masonry shear walls or frame action of the conservatory.

The steel frames were modeled in RISA 3D using finite element modeling. Stresses and deflections were checked against AISC specifications and AISC Design Guides. Spreadsheets were used to check AISC limit states for I and T shaped elements due to the varying depth sections. Secondary moments due to shear effects were considered at T sections, similar to a castellated beam design.

The concept of adding the Solarium to the overall project began when the hotel neared 75% completion. Initially, the Solarium was to be laterally braced solely through the hotel low roof diaphragm using existing masonry shear walls within the hotel. This ended up not being feasible due to a late change in general contractors on the hotel and delays procuring the Solarium itself. The Solarium lateral design was unresolved as the construction of the hotel neared completion. Late additions of X bracing, thicker moment frames or additional shear walls to stabilize the Solarium was not feasible at this point.

The Solarium was laterally braced using stiff W12 cantilevered columns connected to the outside face of the existing hotel foundation wall up to the low connecting roof. These stiff columns resolved the lateral loads from the Solarium into the foundation walls with the help of the existing hotel roof diaphragm and hotel shear walls, without any modification to either design. This creative idea helped keep both buildings on schedule without delay in fabrication and construction.

For more information on this project, please visit Tanglewood Conservatories.