MATH: Fundamentals of Structural Steel Design DOCX

Title	MATH: Fundamentals of Structural Steel Design
Author	M. Domingo
Pages	76
File Size	3.1 MB
File Type	DOCX
Total Downloads	373
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CHAPTER NINETEEN BASE PLATE 19.1 Base Plates for Axially Loaded Columns Steel columns are placed on some type of supporting member or by a concrete footing. A base plate is necessary when a steel column terminates on any reinforced concrete footing to spread the high intensity of stress in the steel to a value that can be safely carried by the reinforced concrete footing. These base plates can be welded lug angles. For small columns these plates are usually shop-welded to the columns, but for larger columns it is necessary to install the plates separately and set them to correct position. The columns are then set and connected to the footing with anchor bolts which pass through the lug angles which have been shop welded to the columns. The NSCP Specifications provides two allowable bearing pressures for concrete supports. a. If the entire concrete area A2 is covered by the plate whose area is A1: FP = 0.35f c ' b. If A1 is less than A2: FP = 0.35f c ' A2 A1 but ¿0.7 f c ' The following stresses are recommended by the NSCP Specs, a. On sandstone and limestone… FP=2.75MPa b. On brick in cement mortar…….FP=1.72MPa c. On the full area of a concrete support...Fp¿0.35 f c ' d. On less than full area of concrete support….Fp¿0.35 f c ' A2 A1 but 0.7f c '...