User:Amanda044/sandbox

11/16: Outline + Draft

Outline

Lead

·       Expand

History

·       Patent

·       First instances

Process

·       Forming Concrete

·       Lifting Slabs

Applications

·       Successful Installations

·       Building Collapses--- what caused them to collapse?

Lift Slab Construction

Axon and Elevation Diagram of Lift Slab Construction

Add to Lead--- (Youtz-Slick Method) This method of construction allows for a large portion of the work to be completed at ground level, negating the need to form floor work in place. The ability to create monolithic concrete slabs makes the lift slab construction technique useful in quickly creating structures with repetitive form work, like parking ramps.

History

This method of construction simultaneously began development in 1948 by both Philip N. Youtz of New York and Thomas B. Slick of Texas. Although the first patent for lift slab construction was given to Slick in 1955, the method of construction is also known as the "Youtz-Slick Method". His patent called for a method that would allow for fabrication to be completed at the ground level, eliminate a large portion of the form-work, create uniform floors of concrete, and reduce the labor to be completed at an elevated level.

Add to Northrup Hall--- Northrup Hall was the first full scale building erected using lift slab construction. Being such, the process drew a crowd of spectators, waiting to see if the structural integrity of the building would hold.

Process

Concrete

To begin, a concrete slab is first poured on the ground level. Subsequent floors and the roof are then poured and formed on top of the initial ground slab. Bond breakers are used between each floor plate to allow the slabs to separate. Along with reducing the form work required to create the slabs, slabs can be easily protected from inclement weather since all of the slabs remain together during the curing process.

Lifting Mechanisms

To assure the security of a structure during the raising of the slabs, the hydraulic jacks, attached to the top of the columns, use synchronized consoles to lift the slabs at an even rate. Conventional methods of mounting the jacks to the columns require that the jacks are removed before continuing to raise the slabs. More recent approaches utilize welded plates, separated from the columns, to support the jack.

Simultaneous Floor and Wall Construction

In Latin America, contractors have started to use a form of lift slab construction where load-bearing concrete walls are raised at the same time as the floor slabs. Both the wall panels and the floor slabs are cast on the ground. The walls are attached to the slabs through hinges formed by plastic ropes. As the floors are raised, the walls unfold into place and form the vertical support for the system.

Applications of Lift Slab Construction

The building located at 2150 Shattuck Avenue in Berkeley, CA (or First Savings Building) is one example of lift slab construction utilized in the Bay Area in the mid-twentieth century. Built in 1969, the First Savings Building utilizes lift slab construction to support the fourteen story height of the building. The buildings structural system is comprised of a system of trusses in which the various concrete slab floors are hung from. In turn, these trusses extend out from two reinforced concrete cores which provide the main structural support for the entirety of the building.

Add to L' Ambiance--- The failure of the structure has been primarily attributed to instability with the steel columns that were meant to support the floors. Although other factors were involved in the collapse while under construction, it is the the insufficient lateral bracing that caused the structural failure.

Additional Readings

1. Elazouni, AM, and ME Abd El-Razek. “Adapting Lift-Slab Technology to Construct Submerged Pile Caps.” Journal of Construction Engineering and Management 126, no. 2 (March 1, 2000): 149,157.
2. Masih, Rusk. “Stability of Lift Slab Structure During Construction Stage,” 271–77. ASCE, 1994. http://cedb.asce.org/CEDBsearch/record.jsp?dockey=0086682.
3. Porter, J.B., and Building Research Institute. Lift-Slab Construction: Its Implications in Building Design and Engineering. Building Research Institute, Division of Engineering and Industrial Research, National Academy of Sciences, National Research Council, 1955. https://books.google.com/books?id=aUsrAAAAYAAJ.

11/9: Contributions to Lift Slab Construction

In the article describing lift slab construction, the actual construction process is only generally described. I plan to add further details, describing the technical process, the components, and any other variations in methods of construction. The article currently mentions some of the structural failures associated with this type of construction, but the article would benefit from seeing some of the successful cases of lift slab construction. Perhaps more sub-headings within the article could be added, splitting the case studies into successes vs. failures, standing vs. collapses, benefits vs. risks, etc.

Along with the above-mentioned additions, I plan to include images and diagrams in order to help visualize lift slab construction and its applications.

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Additional Sources

1. Elazouni, AM, and ME Abd El-Razek. “Adapting Lift-Slab Technology to Construct Submerged Pile Caps.” Journal of Construction Engineering and Management 126, no. 2 (March 1, 2000): 149,157.
2. Feld, J., and K.L. Carper. Construction Failure. A Wiley Interscience Publication. Wiley, 1997. https://books.google.com/books?id=-jnlb-oJxcEC.
3. Guidelines may revive lift-slab technique. (1998). Civil Engineering, 68(1), 18-19.
4. Institute, American Concrete. ACI Manual of Concrete Inspection. Publication SP. American Concrete Institute, 2007. https://books.google.com/books?id=NrjF22uGbX8C.
5. Masih, Rusk. “Stability of Lift Slab Structure During Construction Stage,” 271–77. ASCE, 1994. http://cedb.asce.org/CEDBsearch/record.jsp?dockey=0086682.
6. Masih, Rusk, and Vladimer Hambertsumian. “Reliability of Energy Method to Predict Lift Slab Structures Stability.” Journal of Performance of Constructed Facilities. 12, no. 3 (1998): 153,160.
7. Porter, J.B., and Building Research Institute. Lift-Slab Construction: Its Implications in Building Design and Engineering. Building Research Institute, Division of Engineering and Industrial Research, National Academy of Sciences, National Research Council, 1955. https://books.google.com/books?id=aUsrAAAAYAAJ.
8. Taranath, B.S. Reinforced Concrete Design of Tall Buildings. CRC Press, 2009. https://books.google.com/books?id=A96JR7qkWGgC.
9. Zallen, Rubin M., and David B Peraza. Engineering Considerations for Lift-Slab Construction. Reston, VA: American Society of Civil Engineers, 2004

Looked over by Ashley Losco (11/20/17)