Stress and strain studies of historical masonry

Introduction. Brick masonry of historical buildings has a number of features compared to masonry made of contemporary materials. This applies to both strength and strain characteristics. Incorrectly assessed strain of masonry walls, pillars, etc. can lead to a faulty estimate of the magnitude of forces redistributed between them.

Aim. To obtain experimental data on the strength and strain of masonry made of historical brick, including that constructed with lime mortar; to use the obtained results for strength and strain studies of masonry reinforced by mortar injection, including in combination with indirect reinforcement, in areas with repairs during the restoration of historical masonry with contemporary one, as well as in locations of combined action of backfill and facing layers.

Materials and methods. Compression tests are carried out on historical brick samples in the form of pillars and walls with mortars of various strengths, including lime mortar. Samples with the inner layer (backfill) different in strength and strain from the facing layers are additionally tested for local compression and central compression with a uniformly distributed load.

Results. The main strength and strain characteristics of masonry made of historical brick, including those with lime mortar, are obtained. The research results are used in the development of regulatory documents on masonry structures, as well as recommendations and projects for strengthening the masonry structures of historical buildings.

Conclusions. The elastic characteristics of masonry with lime and complex lime-admixed mortars are below the standard values. The transverse expansion coefficients of masonry (Poisson’s ratio) for various vertical stresses were obtained to be included in regulatory documents. The compressive strength of the masonry significantly exceeds the values specified in the standards, which is largely due to the quality of performed work as well as specifics of historical bricks masonry.

1. <i>Ishchuk M.K., Frolova I.G., Ishchuk E.M.</i> Strengthening of Masonry Structures. Promyshlennoe i Grazhdanskoe Stroitel’stvo = Industrial and Civil Engineering. 2006;(8):28–30. (In Russian).

2. <i>Ishchuk M.K., Ishchuk E.M., Frolova I.G.</i> Strengthening Masonry by Injecting Epoxy Resin. Promyshlennoe I Grazhdanskoe Stroitel’stvo = Industrial and Civil Engineering. 2013;(4):48–51. (In Russian).

3. STO 36554501-010-2008. Strengthening Brickwork by Injecting Epoxy Resin GLOBALPOX I-10/138/BT. Moscow: SC Research Center of Construction; 2008. (In Russian).

4. <i>Ishchuk M.K., Ishchuk E.M., Gogua O.K.</i> Research Institute of Building Constructions named after V.A. Koucherenko, JSC Research Center of Construction. Guidelines for Strengthening Masonry, Including Historic Buildings, by Injecting Mortar [internet]. Moscow; 2019. (In Russian).

5. <i>Onishchik L.I.</i> Stone Structures. Moscow: Stroyizdat Publ.; 1939. (In Russian).

6. <i>Nekrasov V.P.</i> Theory of Masonry Strength. Moscow: Stroyizdat Publ.; 1947. (In Russian).

7. <i>Lent L.B.</i> Brick and Brickwork in the USA: (Research and Testing). Moscow; Leningrad: ONTI. Editor-in-Chief of Construction Literature; 1937. (In Russian).

8. <i>Kameiko V.A., Semenov S.A.</i> Status and Main Directions of Research on the Strength of Masonry Structures. In: Theoretical and Experimental Studies of Masonry Structures: collection of works. Moscow: Stroyizdat Publ.; 1978, pp. 6–45. (In Russian).

9. <i>Onishchik L.I.</i> Explanatory Note to Chapter 3. In: Structural Design Standards: draft. Materials for the Standard Position. Fourth edition. Moscow: Mashstroyizdat Publ.; 1949, pp. 131–152. (In Russian).

10. Chapter 3. Design Standards for Masonry and Reinforced Masonry Structures. In: Structural Design

11. Standards: draft. Materials for the Standard Position. Fourth edition. Moscow: Mashstroyizdat Publ.; 1949, pp. 37–63. (In Russian).

12. NiTU 120-55. Design Standards and Technical Conditions for Masonry and Reinforced Masonry Structures. Kyiv: State Publishing House of Literature on Construction and Architecture; 1956. (In Russian).

13. <i>Onishchik L.I.</i> Performance of Masonry Structures under Load in the Fracture Stage. Research on Masonry Structures: Collection of Articles. Moscow, Leningrad: Stroyizdat Publ.; 1949, pp. 5–44. (In Russian).

14. State Standard 32047-2012. Masonry. Compression Test Method with Amendment No. 1 [internet]. Available at: https://docs.cntd.ru/document/1200101520. (in Russian).