March 2009

If a beam is composed of two or more thin layers placed on each other without any attachment, the separate layers would slide past each other and the total strength of the beam would be the sum of the strengths of the various layers. The strength of this beam is lesser than a solid beam having the same cross-sectional area.
 

Problem 553
Determine the maximum tensile and compressive bending stresses developed in the beam as shown in Fig. P-553.
 

Problem 552
A cantilever beam carries the force and couple shown in Fig. P-552. Determine the maximum tensile and compressive bending stresses developed in the beam.
 

Problem 551
Find the maximum tensile and compressive flexure stresses for the cantilever beam shown in Fig. P-551.
 

Problem 550
Resolve Prob. 549 if the maximum moments are +2.5P lb·ft and -5.0P lb·ft.
 

Problem 549
A beam with cross-section shown in Fig. P-549 is loaded in such a way that the maximum moments are +1.0P lb·ft and -1.5P lb·ft, where P is the applied load in pounds. Determine the maximum safe value of P if the working stresses are 4 ksi in tension and 10 ksi in compression.
 

Problem 548
The inverted T section of a 4-m simply supported beam has the properties shown in Fig. P-548. The beam carries a uniformly distributed load of intensity w_o over its entire length. Determine w_o if f_bt ≤ 40 MPa and f_bc ≤ 80 MPa.
 

Problem 543
A portion of the floor plan of a building is shown in Fig. P-543. The total loading (including live and dead loads) in each bay is as shown. Select the lightest suitable W-shape if the allowable flexural stress is 120 MPa.
 

Flexural Stress varies directly linearly with distance from the neutral axis. Thus for a symmetrical section such as wide flange, the compressive and tensile stresses will be the same. This will be desirable if the material is both equally strong in tension and compression. However, there are materials, such as cast iron, which are strong in compression than in tension. It is therefore desirable to use a beam with unsymmetrical cross section giving more area in the compression part making the stronger fiber located at a greater distance from the neutral axis than the weaker fiber. Some of these sections are shown below.