PSI - Issue 59

Volodymyr Romaniuk et al. / Procedia Structural Integrity 59 (2024) 479–486 Volodymyr Romanіuk et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 1. Steel pre-stressed perforated arch with characteristic cross-sections in the left semi-arch.

The span of the experimental structure is the height of the spacer location is

, the rise is

, the slope of the top chord is 0.5, and

. All geometric parameters adhere to the calculation method proposed by the authors in their works. The initial I-beam of the top chord, designated as No. 12 according to DSTU 8768:2018, was selected based on the ultimate and serviceability limit states. The coefficient of development of the height of its cross-section, according to the performed calculations, is taken . To facilitate testing of such a structure, a special installation was designed and manufactured in the research laboratory. This installation enables the fixation of the structure in its designated position and perform complex experimental studies following the developed methodology. The structure was tested under three load schemes: symmetric, asymmetric and assembly. The symmetric load scheme simulated the real constant loads on the roof, and the asymmetric one – the presence of snow cover only on half of the span. The assembly scheme simulated the scenario of installing the roof on only one side during construction. Furthermore, to demonstrate the practical usage of the developed structure and its calculation methodology, the arch was tested for each load scheme both without a spacer and with a spacer at varying values of the eccentricity of the tightening displacement and with a certain pre-tension of the spacer. In total, 27 loadings of the experimental structure were conducted according to various loading schemes and structural features. During the final stage of experimental research, specifically under the impact of a symmetrical load on the arch with a pre-tensioned spacer, the structure was intentionally subjected to destruction. This destructive testing aimed to ascertain the nature of the failure and determine the magnitude of the destructive load. The full estimated symmetrical evenly distributed load on the arch, considering the own weight of the enclosing roofing structures and snow . The equivalent concentrated nodal force was . Asymmetric load was considered for the case of no snow load on the left half of the span, i.e., the load was considered only from the own weight of the enclosing roof structures on the entire span and snow on the right. The value of the estimated uniformly distributed load on the left half of the arch was 7. , and the equivalent value of the concentrated nodal force was equal to 8 , reflecting the self-weight of the roof structures. The ridge node was loaded with a concentrated force equal to the average value between the loads on the left and right half-arches, specifically . In the process of building construction using such arches, it is possible to install a covering only on half of the span. Therefore, a mandatory step was to load the arch with a one-sided, evenly distributed load from the self weight of the roofing structures equal to 7. on one of the half-arches. The equivalent value of the concentrated nodal force was 8 . Meanwhile, the other semi-arch remained completely unloaded. The pre-tensioning of the arch spacer was performed mechanically using a wrench. The magnitude of the pre tension was 16 and was monitored using strain gauges and tensometric equipment. In general, experimental studies confirmed the developed calculation method and the expediency of using the eccentricity of the tightening displacement or the pre-tensioning of the spacer (Roman і uk and Supruniuk, 2013 ) . It was also established that upon reaching the design load level, no visible damage occurred in the elements of the arch. The resulting stresses in the characteristic sections of the perforated top chord, as well as in other elements, did not exceed the design resistance of the steel.