Problem: Calculate the development length for a 25mm diameter deformed bar in tension. $f_y = 420 \text{ MPa}$, $f'_c = 28 \text{ MPa}$. Bottom bars, uncoated, normal weight concrete. Clear spacing > $2d_b$, clear cover > $d_b$.

Problem: Calculate the development length for a 25mm bar in compression. $f_y = 420 \text{ MPa}$, $f'_c = 28 \text{ MPa}$.

Problem: Determine the development length for a 20mm bar with a standard 90-degree hook in tension. $f_y = 420 \text{ MPa}$, $f'_c = 28 \text{ MPa}$. Side cover > 65mm.

Problem: Determine the required tension lap splice length for 20mm diameter bars. The development length $l_d$ calculated previously is $800 \text{ mm}$. The provided steel area is exactly equal to the required area, and all bars are spliced at the same location.

Problem: A $25 \text{ mm}$ deformed bar is to be anchored in a column footing using a standard 90-degree hook. Determine if the hook provides any development length benefit in compression. $f_y = 420 \text{ MPa}$, $f'_c = 28 \text{ MPa}$. Explain the code provisions regarding hooked bars in compression.

Problem: A heavy precast concrete balcony attached to a building facade suddenly tore away and collapsed. Post-collapse investigation revealed that the top reinforcing bars connecting the balcony slab to the main floor slab were smooth, short dowels that pulled out cleanly from the concrete without yielding. Analyze the mechanism of failure.

Problem: A series of closely spaced, large-diameter bottom bars in a bridge girder were cast with only 15 mm of clear concrete cover to the side face. Over time, longitudinal cracks formed along the length of the bars, and eventually, the entire side cover spalled off, leaving the bars exposed. Explain why inadequate cover leads to bond failure.