During preliminary design estimation for a concrete beam, the width is initially assumed as__________________?
Show answer Hide answer
Answer: D. 1/30th of span
Explanation
During preliminary structural estimation, the width of a concrete beam is commonly assumed as 1/30th of its effective span. This empirical rule-of-thumb provides a reasonable starting dimension for calculating self-weight and bending moments. Initial proportioning based on span length ensures that the beam will have adequate stiffness during early design phases. Preliminary sizing allows structural engineers to estimate member dimensions before performing rigorous load and stress analyses. Beam proportions are typically expressed as fractions of the clear or effective span to satisfy deflection criteria. Standard rules help streamline the design workflow for reinforced concrete framing systems in commercial buildings.
Option A suggests a thicker beam proportion which is generally reserved for heavily loaded or continuous members. Option B provides a ratio typically used for preliminary depth estimation rather than beam cross-section width. Option C yields a wider preliminary proportion than standard empirical rules recommend for typical concrete beams.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Beam cross-sectional dimensions must be revised if the calculated shear stress exceeds_______________?
Show answer Hide answer
Answer: C. 20 kg/cm2
Beam cross-sectional dimensions must be revised if the calculated nominal shear stress exceeds the maximum allowable limit of 20 kg/cm2. Exceeding the maximum permissible shear stress causes brittle diagonal compression...
Q2. A short column measuring 20 cm × 20 cm contains 4 longitudinal bars with a combined cross-sectional area of 20 sq. cm. With permissible compressive stresses of 40 kg/cm2 for concrete and 300 kg/cm2 for steel, the safe axial load capacity should not surpass_______________?
Show answer Hide answer
Answer: B. 41,200 kg
Using allowable stress formulas for concrete and steel areas, the safe axial load capacity for the short column calculates to 41200 kg. Multiplying the allowable concrete stress by its net cross sectional area gives the...
Q3. Columns may be constructed using plain concrete provided their unsupported heights do not exceed their least lateral dimension multiplied by_______________?
Show answer Hide answer
Answer: C. Four times
Plain concrete columns may be constructed provided their unsupported heights do not exceed four times their least lateral dimension. Without internal steel reinforcement to handle tensile stresses, plain concrete columns...
Q4. In the case of a ribbed floor slab______________?
Show answer Hide answer
Answer: D. All the above
Ribbed floor slabs are governed by specific geometric limits regarding rib width, clear spacing, and overall depth relative to breadth. Code provisions ensure that concrete ribs have sufficient width for placing reinforc...
Q5. For standard structural cases, the stiffness requirement of a simply supported beam is met if the span-to-overall-depth ratio does not exceed________________?
Show answer Hide answer
Answer: C. 20
For standard structural cases, deflection control and stiffness requirements for a simply supported beam are met if the span to overall depth ratio does not exceed twenty. Limiting the span to depth ratio prevents excess...
Q6. The distribution profile of shear stress across a rectangular beam section follows_________________?
Show answer Hide answer
Answer: C. A parabolic curve
The distribution profile of transverse shear stress across a rectangular beam cross-section follows a parabolic curve. Shear stress is zero at the extreme top and bottom fibers where bending stresses reach their maximum...