ktny
Structural
- Oct 14, 2003
- 1
I recently saw an embeded steel link beam design that used the method described in PCI design handbook 5th edition, section 6.9 Structural Steel Haunches, where it resolved the applied moment into two compression zones on top and bottom flanges (bearing on concrete). Simply, the bearing forces (one near the face of the concrete shear wall, and the other at the end of the steel link beam) separated by the moment arm resists the applied moment.
I also saw an example of an embeded steel link beam design where the applied moment was resolved into top and bottom flanges of the beam as compression and tension forces, which were then resolved into the shear wall through a number of studs. Here, the pull out force of the concrete was checked on the tension side of the linkbeam. Also, the web of the beam did not extend the full length of the flanges but only a short way into the shear wall, enough to take the shear force in the beam.
The main difference between the two was that the method described by PCI decreased the embeded length of the link beam but the vertical (shear and bearing) load on the web of the linkbeam was greater. On the other hand, the method utilizing the studs had large embedment length to develop enough pullout strength in the concrete and to accommodate the number of required studs, but the shear force in the beam was less.
I was wondering, which one of these methods are widely used in the industry, and if both of them are used equally often, when and where should each method be utilized to optimize the design. In a highrise, I would think the large link beam forces (both moment and shear) would be significant in determining the construction of the link beams depending on the method chosen.
Thanks.
ktny
I also saw an example of an embeded steel link beam design where the applied moment was resolved into top and bottom flanges of the beam as compression and tension forces, which were then resolved into the shear wall through a number of studs. Here, the pull out force of the concrete was checked on the tension side of the linkbeam. Also, the web of the beam did not extend the full length of the flanges but only a short way into the shear wall, enough to take the shear force in the beam.
The main difference between the two was that the method described by PCI decreased the embeded length of the link beam but the vertical (shear and bearing) load on the web of the linkbeam was greater. On the other hand, the method utilizing the studs had large embedment length to develop enough pullout strength in the concrete and to accommodate the number of required studs, but the shear force in the beam was less.
I was wondering, which one of these methods are widely used in the industry, and if both of them are used equally often, when and where should each method be utilized to optimize the design. In a highrise, I would think the large link beam forces (both moment and shear) would be significant in determining the construction of the link beams depending on the method chosen.
Thanks.
ktny
