Section 1708: In-Situ Load Tests
2018 Philadelphia Building Code (Chapter 17: Special Inspections and Tests)
1708.1 General
Whenever there is a reasonable doubt as to the stability or load-bearing capacity of a completed building, structure or portion thereof for the expected loads, an engineering assessment shall be required. The engineering assessment shall involve either a structural analysis or an in-situ load test, or both. The structural analysis shall be based on actual material properties and other as-built conditions that affect stability or load-bearing capacity, and shall be conducted in accordance with the applicable design standard. The in-situ load tests shall be conducted in accordance with Section 1708.2. If the building, structure or portion thereof is found to have inadequate stability or load-bearing capacity for the expected loads, modifications to ensure structural adequacy or the removal of the inadequate construction shall be required.
1708.2 In-Situ Load Tests
In-situ load tests shall be conducted in accordance with Section 1708.2.1 or 1708.2.2 and shall be supervised by a registered design professional. The test shall simulate the applicable loading conditions specified in Chapter 16 as necessary to address the concerns regarding structural stability of the building, structure or portion thereof.
1708.2.1 Load Test Procedure Specified
Where a referenced material standard contains an applicable load test procedure and acceptance criteria, the test procedure and acceptance criteria in the standard shall apply. In the absence of specific load factors or acceptance criteria, the load factors and acceptance criteria in Section 1708.2.2 shall apply.
1708.2.2 Load Test Procedure Not Specified
In the absence of applicable load test procedures contained within a material standard referenced by this code or acceptance criteria for a specific material or method of construction, such existing structure shall be subjected to an approved test procedure developed by a registered design professional that simulates applicable loading and deformation conditions. For components that are not a part of the seismic force-resisting system, at a minimum the test load shall be equal to the specified factored design loads. For materials such as wood that have strengths that are dependent on load duration, the test load shall be adjusted to account for the difference in load duration of the test compared to the expected duration of the design loads being considered. For statically loaded components, the test load shall be left in place for a period of 24 hours. For components that carry dynamic loads (for example, machine supports or fall arrest anchors), the load shall be left in place for a period consistent with the component’s actual function. The structure shall be considered to have successfully met the test requirements where the following criteria are satisfied:
- Under the design load, the deflection shall not exceed the limitations specified in Section 1604.3.
- Within 24 hours after removal of the test load, the structure shall have recovered not less than 75 percent of the maximum deflection.
- During and immediately after the test, the structure shall not show evidence of failure.
💡 Special Inspector's Commentary
Section 1708 comes into play when the structural integrity of an existing building is called into question. This "reasonable doubt" is often triggered by age-related deterioration, fire damage, unpermitted contractor modifications, or direct Make Safe Violations issued by the Philadelphia Department of Licenses and Inspections (L&I).
When the actual material properties or as-built conditions are unknown, an in-situ load test must be conducted under the direct supervision of a Registered Design Professional. As licensed structural engineers in Philadelphia, Viking Engineers can develop and supervise the approved load test procedures, analyze the deflection and recovery metrics, and provide the engineering assessment required to prove your structure is safe or identify the precise modifications needed to bring it up to code.