GATE Exam Questions Questions

• Effective flange width of a reinforced concrete T-beam in compression (IS 456 concept) Let l0 be the distance between adjacent points of zero moment, b the rib (web) width, and D the flange thickness. According to IS 456 (conceptual form), the effective flange width beff may be taken as:
• Working stress design (IS 800:1984) — factor of safety for axial compression What factor of safety did IS 800:1984 adopt while arriving at the permissible stress in axial compression?
• Bituminous emulsions in highway works — typical applications In flexible pavement construction and maintenance, bitumen emulsions are mainly used in:
• Effective vertical stress beneath a river — sand bed saturated unit weight given A river has 5 m of water overlying a sand bed. The sand has saturated unit weight γ_sat = 20 kN/m^3 and the unit weight of water γ_w = 9.81 kN/m^3. Determine the effective vertical stress at a point located 5 m below the top surface of the sand bed (i.e., 5 m into the sand, beneath 5 m of water).
• Groundwater — storage coefficient of a compressible confined aquifer For a confined aquifer with finite compressibility, on what parameters does the storage coefficient (S) primarily depend?
• Flow through porous media — proportionality in Darcy’s law According to Darcy’s law for laminar flow through a saturated porous medium, the average (Darcy) velocity is directly proportional to which parameter?
• Open-channel rating — estimating discharge from slope change at same stage A river reach has discharge Q1 = 173 m^3/s when the water-surface slope S1 = 1/6000 and the stage at the gauge is 10.0 m. During a flood, the stage remains 10.0 m but the water-surface slope increases to S2 = 1/2000. Assuming the cross-section and roughness are unchanged (uniform flow at the same stage), estimate the new discharge.
• Prestressed concrete — concrete stress at transfer with tendons at the CG A pre-tensioned concrete member has a 200 mm × 250 mm rectangular section. Tendons of total area A_s = 500 mm^2 are located at the section’s centroid. The initial prestress in steel is f_si = 1000 N/mm^2. Assuming modular ratio m = E_s/E_c = 10 and instantaneous elastic shortening only, compute the uniform compressive stress in concrete at transfer.
• Regime channel design (Lacey) — mean velocity expression A stable alluvial channel is to be designed to carry discharge Q (m^3/s) with silt factor f according to Lacey’s method. What is the expression for the mean regime velocity V (m/s)?
• Wastewater quality — what does BOD measure? Biochemical oxygen demand (BOD) of wastewater is primarily a measure of which constituent class?
• Head loss due to sudden expansion — key assumption in derivation When deriving the expression for head loss in a sudden expansion of a pipe using continuity and the impulse–momentum equation, which additional assumption is made about the separated eddying fluid in the expansion zone?
• Geodetic visibility of a lighthouse over the sea horizon A lighthouse has a height of 120 m above mean sea level and is just visible above the horizon from a ship at sea level. Considering the combined correction for Earth’s curvature and standard atmospheric refraction, determine the correct horizontal distance between the ship and the lighthouse, expressed in metres.
• Potable water assessment – single most important parameter for domestic use For judging the suitability of a water supply for domestic (drinking) purposes, which water quality parameter is considered the most important indicator of safety?
• Zero-air-voids (saturation) unit weight – dependent variables At zero air voids (100% saturation), the unit weight of soil depends on which of the following basic quantities?
• Rigid pavements – principal function of a base (sub-base) layer In cement concrete pavements, what is the primary reason for providing a base/sub-base course beneath the slab?
• Definition of a shallow foundation based on depth-to-width ratio A foundation is classified as shallow if its depth (measured from ground level to foundation base) is:
• Unconfined compressive strength (UCS) range for stiff clay Classify the unconfined compressive strength of a ‘‘stiff’’ clay by choosing the appropriate UCS range (kN/m²).
• Prestressed concrete beam – stress at the top fibre due to prestress only A rectangular beam 300 mm wide by 900 mm deep is prestressed with an initial force P = 700 kN applied at midspan with an eccentricity e = 350 mm relative to the centroidal axis (eccentricity taken towards the top fibre). Determine the stress at the top of the section due to prestress alone, in N/mm² (state the sign).
• Backwater curve in a long mild-slope prismatic channel ending in a pool A long prismatic channel has a mild bed slope. Its downstream end discharges into a pool created by a dam (high tailwater). Identify the resulting gradually varied flow water surface profile upstream of the pool.
• Plate Bearing Test – Interpreting an Inflated Tyre Load In a plate bearing (plate load) test for pavement/subgrade evaluation, if the applied load is delivered through an inflated pneumatic wheel (tyre) rather than a rigid steel plate, the loading mechanism most closely corresponds to which idealized plate behavior?