Types of cracks in the beam
The large ceiling beams hanging around in the modern office or the ordinary room make it remarkable and creates a visual impact. A Beam is a long stout piece of metal or timber used as horizontal support for a building, and it transfers the load to a vertical load-bearing element of the structure. The connecting beam forms the structural skeleton of a building. The grid of beams and columns is used to construct a concrete foundation and support the building's floors, walls, roof, cladding, etc. The rays can crack due to various reasons such as pest damages, natural aging, overloading, environmental issues, and failure of other supporting structures below the beam. If you are unsure of the severe crack damages in the beam, here are the two methods to check it out. The first method is to hold the string tightly between the shaft's ends and check for sagging. If it is so, then the beam is falling apart and is affecting the integrity of the structure. The second method is to fix the masking tape over the crack and check if it stays over time. If it is ripped apart, it means that the gap is widening, and the appropriate measures have to be taken immediately to fix it or rebuild it.
The six common types of cracks in the beam are,
1. Flexural / Tensile Cracks: These types of damages occur due to the Tensile Stresses. When the external waterproofing company Bangalore forces are applied to the beam concrete structure, the bending stress is developed. It is of two types: joyous bending moment called sagging and negative bending moment called hogging. The maximum tension is at the mid-portion on the bottom side and looks perpendicular to the sagging's neutral axis. In hogging, the maximum pressure is at the support region on the top side. The prevention of tensile crack is done by providing a higher and lesser reinforcement while designing the beam structure.
2. Shear Cracks: This crack occurs due to the Shear Stresses. The shear forces act on the joints of the support structure, beams, walls, and columns at the bottom side face, and it is more than the strength of the shaft. So it creates the crack bend at a 45-degree angle. Note that the shear stresses have little value at the mid-span of the beam, and no cracks are developed. But it creates cracks at joints on the lateral side of the shaft. The prevention of shear crack is done by providing a higher and lesser reinforcement while designing the beam structure.
3. Combination of Flexural and Shear Cracks: This crack development is due to the Tensile and Shear Stresses's combination. Here, the stresses appear at both the top and bottom side faces and create cracks perpendicular at first but inclined later.
4. Cracks due to corrosion: Usually, the beam's top face is covered with a slab, but the bottom part is exposed to the environment. If the concrete cover is insufficient, then the reinforcement's corrosion occurs, and the cracks are formed. These micro-cracks at the bottom of the beam on the arms, parallel to the beam orientation. This type of damages can be prevented by using sufficient concrete cover.
5. Cracks appearing due to the beam structure's compression failure: The compression force acting on the beam results in compressive stress. If this stress reaches its maximum, it will push the beam in the inward direction, resulting in a crack formation.
6. Crack formation due to the insufficient use of rebars in the beam: The reinforcement bars or rebars increase the concrete's tensile strength. It also helps to prevent the cracks from getting more expansive. If it is insufficient, it leads to cracking and breaking of the concrete beam.
How do you repair the cracks on the Reinforced concrete beams? The cracks on the reinforced concrete beams are to be fixed immediately, as it affects the integrity of the structure and poses safety issues to the people.
Step 1: Before repairing the cracks, first examine the reason and the extent of damage to the beam structure.
Step 2: Check the condition of jack posts or the lally columns for any cracks, deflection, or rusting.
Step 3: Once all the support jack posts are structurally sound, the beam cracks can be fixed.
Step 4: The quick way to repair the beam is to use angle iron to the steel angle's supporting shaft.
Step 5: Next, make holes in the angle iron with intervals to insert the lag screws through it.
Step 6: Remove any utility lines that run through the beam, maybe plumbing, electrical, or power lines.
Step 7: Use joist hangers at the part that needs to be fixed. once the joist is pried, you can use the jack and the temporary post to push up the angle iron
Step 8: Once the angle iron is wedged against the support beam, you should use lag screws to screw up the angle iron onto the support beam.
Step 9: After fixing, the jack and the quick post are removed.
Step 10: Some Effective methods to prevent the collapse of support beams are retrofitting and jacketing, and reducing the beam load. In case of the crack continues to grow in width, consider rebuilding the support beam.
Cracks and their expansion are the precursors of any structural damage or collapse of the building. It also reduces the bearing capacity, and so a structural strengthening system is needed.