This could be found in the ACI318, Chapter 20,”Strength
Evaluation of Existing Structures” Section 20.3 “Load Test Procedure”. Based on
this reference, the total test load, including the dead load already in place,
shall not be less than “0.85 [(1.4D + 1.7L)] – un-factored weight” of the slab
where D is the total un-factored dead load and L is the total un-factored live
The following steps should be carried out on site:
� Calibrated dial gauges should be fixed at the bottom of the slab to measure
the expected deflection. Five (5) gauges should be used to monitor the
deflection in the case of loading.
� The gauges should be set to an initial reading.
� Special precautions should be made to prevent any vibrations in the testing
� Test load provided by the contractor should be uniformly distributed on the
slab according to the intensities indicated in the cases of loading.
� Test load should be applied in four (4) approximately equal increments.
� Response measurements should be recorded after completion of each Increment
� After completion of four (4) loading increments, the slab should be kept
loaded for 24 hours after which deflection readings and response measurement
should be taken.
� The slab will be unloaded. Final response measurements should be done after
unloading directly then after 24 hrs from removal of test load in order to
indicate residual deflection.
the measured maximum deflections shall satisfy one of the following two
� ?max ? L2 / 20,000h
� ?rmax ? ?max / 4
?max: is the maximum deflection in mm
?rmax: is the maximum residual deflection in mm
L2: is shorter of:
(a) Distance between centers of supports in mm.
( Clear distance between supports plus thickness of member in mm.
h: is the thickness of the slab in mm.