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Lateral support and skin reinforcement for reinforced beam

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The buckling of the unsupported beam with any dimension even narrow and deep is a rare occurrence. If the beam subjected to appreciable lateral torsion. ACI code [10.4.1] stating that lateral support is not required to placed closer than 50 times b, where b is the least width of compression face or flange.however, it must be considered in determining the maximum spacing for lateral support.






Skin Reinforcement for Deep Beams
ACI code [10.6.7] stating that skin reinforcement shall be added for beams with depth h is 400 mm or more, the purpose of this reinforcement is to control cracks in the upper part of the tension zone, this reinforcement will be distributed in both vertical faces of the beam within a distance of h/2 from the tension zone as shown in figure 1,
Figure 1










spacing between skin reinforcement shall be according to ACI code [10.6.4], 

S=380(280/fs)-2.5Cc and not greater than S=300*(280/fs)

where 

fs is the calculated closest to the tension face at service load shall be computed based
on the unfactored moment. It shall be permitted to take fs as 2/3fy.
Cc is the least distance from the surface of skin reinforcement or prestressing reinforcement to the side face.

skin reinforcement may be used to calculate the beam flexural strength if the correct strains for the additional reinforcement related to the neutral axis are used to calculate bar stresses. ACI doesn't state any amount of skin reinforcement, it is only stating that additional reinforcement shall be added in the vertical faces of tension zone to prevent excessive cracking. skin reinforcement doesn't have to exceed the half of bending tensile reinforcement



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My name is Mohammad Hamdan, and I am a Civil/bridge Engineer with extensive professional background and experience in the field of construction. I have 10+ years of experience in the construction field. During my professional career, my emphasis has been placed on structural projects, mainly bridges, infrastructure and roads. Reading and practicing the design of structures is my passion.i was lucky to be a part of a big team that executed major highway interchanges. I believe in spreading the knowledge, thus, i compose these courses to share my experience and knowledge. My course focuses on the practical side of construction field. On other word, i am sharing some of what new engineers need to know about construction field. Beside working on construction field, i love writing some articles on my website ( curious civil engineer) Moreover, i wrote some engineering papers, you can check them  by searching my name on Google (Mohammad mamon Hamdan)