What is the maximum lateral pressure formula for concrete placement rates ≤ 7 ft/hr?

P_max = 150 + 9000R/T (where R = rate, T = temperature)

Scaffolds must be secured against lateral movement with what maximum height-to-base ratio?

4:1 maximum unsupported height-to-base ratio

True or False: Temporary structures may use different safety factors than permanent structures.

True. They use reduced design life considerations and controlled loading conditions.

What are the three main categories of excavation support systems?
A) Sloping, shoring, shielding
B) Cutting, bracing, anchoring
C) Trenching, walling, banking
D) Grading, supporting, protecting

A) Sloping, shoring, shielding

The active earth pressure coefficient K_a equals _____.

Tan²(45° - φ/2)

What happens to wood shore capacity when load duration factor C_D increases?

Shore capacity increases because temporary loading allows higher stress levels.

Heavy-duty scaffolding must support what minimum load per square foot?

75 psf (360 kg/m²)

Which factor does NOT affect lateral concrete pressure on formwork?
A) Rate of placement
B) Concrete temperature
C) Reinforcing steel grade
D) Height of placement

C) Reinforcing steel grade

True or False: Formwork deflection limits are typically L/180 for structural applications.

False. Limits are L/240 for structural formwork and L/360 for finishes.

What is the load duration factor C_D for 7-day construction loading?

1.25

Lateral earth pressure at depth z equals _____.

K_a × γ × z

Why do temporary structures allow increased soil bearing capacity?

Short load duration reduces probability of extreme loading events.

What is the minimum point load requirement for scaffolding?

250 lb (114 kg) at any point

For concrete placement rates > 7 ft/hr, which pressure equation applies?
A) P = 150 + 9000R/T
B) P = 150 + 43,400/T + 2800R/T
C) P = 150h
D) P = 3000 psf maximum

B) P = 150 + 43,400/T + 2800R/T

True or False: Steel shores use a resistance factor φ_c = 0.85 for compression.

False. The resistance factor φ_c = 0.90 for compression in steel columns.

Column stability factor C_P accounts for what structural behavior?

Buckling failure in compression members

The apparent pressure for braced sand excavations equals _____.

0.65 × K_a × γ × H

What causes reduced lateral concrete pressure at higher temperatures?

Faster concrete setting reduces hydrostatic pressure development time.

Medium-duty scaffolding design load is what value?

50 psf (240 kg/m²)

Which connection type is NOT typical for temporary structures?
A) Couplers
B) Pins and wedges
C) Welded joints
D) Bolted connections

C) Welded joints

True or False: Excavations 5 feet deep always require protective systems.

True. OSHA requires protection for excavations 5 feet or deeper.

Critical buckling stress for steel columns when KL/r > 4.71√(E/F_y) equals _____.

0.877F_e

What happens to earth pressure when soil friction angle increases?

Active earth pressure coefficient decreases, reducing lateral pressure.

Wind velocity pressure formula includes what four factors?

Q_z = 0.00256 × K_z × K_zt × K_d × V²

For soft clay excavations, apparent pressure distribution is typically:
A) Triangular
B) Rectangular
C) Trapezoidal
D) Parabolic

C) Trapezoidal

True or False: Temporary bridges may use 10-year wind speeds instead of 50-year.

True. Reduced recurrence intervals account for shorter exposure periods.

Maximum concrete pressure is limited to _____ psf or 150h, whichever is less.

3,000