5.4evaluation by load tests

5.4.1 General Requirements

This section applies only to static vertical gravity loads applied to existing roofs or floors.

Where load tests are used, the EOR shall first analyze the structure, prepare a testing plan, and develop a written procedure for the test. The plan shall consider collapse and/or excessive levels of permanent deformation, as defined by the EOR, and shall include procedures to preclude either occurrence during testing.

5.4.2 Determination of Load Rating by Testing

To determine the load rating of an existing floor or roof structure by testing, a test load shall be applied incrementally in accordance with the EOR’s plan. The structure shall be visually inspected for signs of distress or imminent failure at each load level. Measures shall be taken to prevent collapse if these or any other unusual conditions are encountered.

The tested strength of the structure shall be taken as the maximum applied test load plus the in-situ dead load. The live load rating of a floor structure shall be determined by setting the tested strength equal to 1.2D + 1.6L, where D is the nominal dead load and L is the nominal live load rating for the structure. For roof structures, $L_{r}, S$, or $R$ shall be substituted for $L$,

where

$L_{r}=$ nominal roof live load

$R=$ nominal load due to rainwater or snow, exclusive of the ponding contribution

• $S=$ nominal snow load

More severe load combinations shall be used where required by the applicable building codes.

Periodic unloading is permitted once the service load level is attained, and after the onset of inelastic structural behavior is identified, to document the amount of permanent set and the magnitude of the inelastic deformations. Deformations of the structure, such as member deflections, shall be monitored at critical locations during the test, referenced to the initial position before loading. It shall be demonstrated, while maintaining maximum test load for one hour, that the deformation of the structure does not increase by more than 10% above that at the beginning of the holding period. It is permissible to repeat the test loading sequence if necessary to demonstrate compliance.

Deformations of the structure shall also be recorded 24 hours after the test loading is removed to determine the amount of permanent set.

Where it is not feasible to load test the entire structure, a segment or zone of not less than one complete bay representative of the most critical condition shall be selected.

5.4.3 Serviceability Evaluation

Where load tests are prescribed, the structure shall be loaded incrementally to the service load level. The service test load shall be held for a period of one hour and deformations shall be recorded at the beginning and at the end of the one-hour holding period.