Blog

Compute the axial compressive strength Pn and moment capacity Mn of the following tied column when the largest strain in the concrete is 0.003 and the strain in the tension reinforcement is 0.003. Note that you should not include φ in the answer and that you should not consider Pn,max.b = 12 in.h = 20 in.Clear cover to ties = 1.5 in.Number of longitudinal bars = 6Size of longitudinal bars = No. 9Size of ties = No. 3Concrete strength = 3,500 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 60,000 psi

To reduce the chance of field errors, all of the bars in a column should have splices of the same length, regardless of whether they are on the tension or compression face.

Almost universally, an even number of bars is used in rectangular columns, so that the column is symmetrical about the axis of bending.

Determine the maximum axial strength φPn,max for the following tied column.Column width, b = 22 in.Column thickness, h = 26 in.Number of longitudinal bars = 12Size of longitudinal bars = No. 10Size of ties = No. 4Concrete strength = 7,500 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 60,000 psi

Use the interaction diagrams found in Appendix A of the textbook to determine whether the following circular spiral column can safely support a load of Pu = 509 kip and Mu = 381.7 kip-ft.h = 18 in.fc’ = 4 ksify = 60 ksiγ = 0.9ρg = 0.05

Compute the axial compressive strength Pn and moment capacity Mn of the following tied column when the largest strain in the concrete is 0.003 and the strain in the tension reinforcement is 0.003. Note that you should not include φ in the answer and that you should not consider Pn,max.b = 16 in.h = 22 in.Clear cover to ties = 1.5 in.Number of longitudinal bars = 6Size of longitudinal bars = No. 9Size of ties = No. 3Concrete strength = 3,000 psiYield strength of longitudinal bars = 60,000 psiYield strength of ties = 60,000 psi

In nonseismic areas, spiral columns are used more extensively.

ACI 318-14 Table 20.6.1.3.1 requires a clear concrete cover to the ties and spirals in columns of not less than _______.

Spiral reinforcement acts to restrain the longitudinal expansion of the column core under high axial loads and delays the failure of the core, making the column more ductile.

In seismic regions, ties are normally spaced further apart.