If the effect of a strength deficiency is well understood and it is practical to measure the dimensions and determine the material properties of the members required for analysis, an analytical evaluation of strength based on this information is permitted. Required data shall be determined in accordance with 27.3.
If uncertainty about the strength of part or all of a structure involves deterioration, and if the observed response during the load test satisfies the acceptance criteria in 27.4.5, the structure or part of the structure is permitted to remain in service for a time period specified by the licensed design professional. If deemed necessary by the licensed design professional, periodic re-evaluations shall be conducted.
Dimensions of members shall be established at critical sections.
If required, an estimated equivalent fc' shall be based on analysis of results of cylinder tests from the original construction or tests of cores removed from the part of the structure where strength is in question.
The method for obtaining and testing cores shall be in accordance with ASTM C42.
If dimensions, size, and location of reinforcement, and material properties are determined in accordance with 27.3.1, it is permitted to increase ϕ from the design values elsewhere in this Code; however, ϕ shall not exceed the limits in Table 184.108.40.206.
Table 220.127.116.11—Maximum permissible strength reduction factors
|Strength||Classification||Transverse reinforcement||Maximum permissible ϕ|
|Flexure, axial, or both||Tension controlled||All cases||1.0|
|Shear, torsion, or both||0.8|
Load tests shall be conducted in a manner that provides for safety of life and the structure during the test.
A precast member to be made composite with cast-in-place concrete shall be permitted to be tested in flexure as a precast member alone in accordance with (a) and (b):
(a) Test loads shall be applied only when calculations indicate the isolated precast member will not fail by compression or buckling.
Response measurements, such as deflection, strain, slip, and crack width, shall be made at locations where maximum response is expected. Additional measurements shall be made if required.
The initial value for all applicable response measurements shall be obtained not more than 1 hour before applying the first load increment.
A set of response measurements shall be recorded after each load increment is applied and after Tt has been applied on the structure for at least 24 hours.
A set of final response measurements shall be made 24 hours after Tt is removed.
The portion of the structure tested shall show no spalling or crushing of concrete, or other evidence of failure.
Members tested shall not exhibit cracks indicating imminent shear failure.
In regions of members without transverse reinforcement, structural cracks inclined to the longitudinal axis and having a horizontal projection greater than the depth of the member shall be evaluated. For variable-depth members, the depth shall be measured at the mid-length of the crack.
Measured deflections shall satisfy (a) or (b):