Large Scale Structures Laboratory

A researcher during the curved bridge experiment

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See photos of our lab set up, including access and fabrication space, on our photo gallery.

Design criteria (load ratings)

The test floor was designed as a continuous one-way slab spanning the narrow direction of the Laboratory from one exterior wall to the other, and supported on three intermediate load-bearing walls.

Two-way plate action was considered at boundaries, discontinuities and for the distribution of large point loads applied to the slab.

The capacity of the floor for loads distributed over large areas, is determined by the flexural reinforcement. Based on ACI, and using appropriate strength reduction factors, the flexural capacity per unit length of slab is estimated to be 300 K-ft/ft (1335 kN-m/m).For concentrated loads, the capacity is controlled by shear and this is estimated to be 40 K/ft (584 kN/m), again based on ACI.

Using load factors of 1.4 for dead loads and 1.7 for live loads, the rated load of the test floor is estimated as follows:

  • Uniform loads and patch loads of any size, in balanced or unbalanced configurations, in any direction up or down: 3.4 K/sq ft(163 kN/sq m)
  • North-south line loads, in any single slab, in any direction up or down: Varies linearly from 35 K/ft (511 kN/m) at mid span to 23 K/ft (336 kN/m) at 3 ft (0.93 m) from the supports
  • Single point loads, with no other load applied within 12 ft (3.7 m) of the load, and not adjacent to the basement stair openings: 300 K (1335 kN) upward, 240 K (1068 kN) downward

A lower live load factor of 1.4 may be used for experimental live loads that are controlled and monitored. In this case the above load ratings may be increased by 20%.

The box girder test floor weighs about 5000 K (22,250 kN). Desirable mass ratios of between 50 and 100 imply that specimen weights for dynamic tests should be in the range of 50 to 100 K (222 to 445 kN).

Natural lighting is provided by skylights in the roof and a bank of windows in the north wall. Electric power (110 and 220 volt), compressed air and water outlets are provided around the perimeter wall and in the basement (except for 220 volt lines). A control room is available on the west side of the test floor.