Irreversible shifts in structures statically stable against displacement as the result of cyclic temperature fluctuations

Conclusions

• 1. A concrete slab or rock mass, exposed to the action of a constant displacement force, statically stable against displacement, will be subjected to slow irreversible displacements under the action of temperature fluctuations.

• 2. When irreversible temperature shifts cannot be tolerated, connections must be included in the system so that the expansions and contractions occurring on account of temperature fluctuations are absorbed within the limits of elastic deformations.

• 3. At present, irreversible shifts are not included in programs of full-scale observations or geologic prospecting works. Such displacements, however, may be important in the overall set of conditions governing the performance of a hydraulic engineering installation or particular features of the geological structures. In some cases, determination of the possibility of irreversible shifts may assist in the correct interpretation of settlement and stress observations on structures.

There is no doubt that movements similar to those described above are common in nature and can be observed frequently, if readings are taken with the necessary accuracy embracing a sufficient number of heating and cooling cycles on an investigated structure, natural rock feature, earth slope, etc.