System Alternates and Sections

General:

Many offices seen and built today have the general theme of square box frame with an interesting curtain wall or facade. Going further, the structural system can become more complicated with the addition of more simple boxed frames placed at different angles or heights. In the case of the ASCE National Headquarters the simple box frame structural system is used. This type of structural system effectively distributes loads from each floor to columns and into the ground. Its also allows for maximum spans creating open spaces on floors. The structural selection process used for the ASCE National Headquarters was easy but thought was given to some possible other structural systems. From the Architectural Studio Companion the structural system can be selected.

 

Architectural Studio Companion Ch.1, Basic Selection (Below):

Architectural Studio Companion Ch.1, Basic Selection (Below):

 

Architectural Studio Companion Ch.1, Basic Spans (Below):

Architectural Studio Companion Ch.1, Office Live Loads (Below):

Wood:

The wood frame structural systems are an economical alternative in some cases. Timber structures have the ability to make unique designs and many architectural styles. Wooden frames can effectively transfer loads to the ground. Loads are carried by a roof truss to the walls, which are load bearing. The load then is transferred into the foundation structure and into the ground. Using a wood frame structural system does not prove to be the best selection for the ASCE National Headquarters, due to the multistory construction.

 

Architectural Studio Companion Ch.1, Office Structural Selection (Below):

Steel:

Using a steel frame structure is the best selection for the ASCE National Headquarters. Steel frames provide for great horizontal and vertical loads bearing capacity. A total estimated load to be supported by the structure is 5,550 kips. Such loading is common for steel frame with concrete foundations buildings. It also allows for a good range of floor to floor heights and spans between columns. The maximum span is 40′ on center. While there is a multitude of steel beam shapes which can accommodate such spans, finding appropriate wood member would be a challenge. Generally, for the office type buildings, time of construction is directly related to the building cost. Steel frame is easy and fast to construct, while cutting down the cost of construction. Concrete building would  lengthen the project duration. Also, the construction is simplifies, because  the same size steel columns can be used for every floor for a 5 story structure, without a significant impact to the materials cost.

 

 

Concrete:

Concrete Slabs and Columns (Below):

Concrete provides options in multistory office building construction. A structural designer can institute a cast in place, off site precast, or mixed concrete slab with steel frame work. Cast in place concrete work is labor intensive but can provide for unique on site forming. The work and materials used can be well monitored, which provides a sound structure for the building. The off site precast method is constructed like a puzzle. Large sections are transported to the site and a crane will hoist each section to the designation area. For walls a “tilt up” method can be used to put large sections into place. Lastly, a steel frame with concrete slab floors is a common method and is heavy consider for the ASCE National Headquarters structural system.

 

Architectural Studio Companion Ch.1, Office Structural Selection (Below):

Tilt Up Construction (Below):

Concrete is a strong material in compression. Used in columns and slab floors, either poured in place or precast, it can provide a strong structure for large heights and reasonable spans in floor layout.

 

 

Steel Selection Preliminary Design:


Architectural Studio Companion Ch.1, Live Load Ranges (Below):


Architectural Studio Companion Ch.1, Lateral Stability (Below):

 

 

Resources:

http://woodframesystem.wordpress.com/wood-frame-system/

– Architectural Studio Companion

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