Investigation of the effects of lateral bracing on improving the reliability and serviceability of truss guard structures

Abstract With the increase of construction in urban areas, the increase of high-rise construction and as a result the increase in the need for semi-deep and deep excavations, the importance of design and implementation of guard structures has become more than before. Truss guard structures are considered as one of the main options in excavation projects due to their lower cost, easier execution and less need for executive specialized personnel. Examination of the experiences of damages caused during excavation with truss guard structure shows that the defects in the joints and the lack of adequate lateral restraints are among the main reasons for the failure of these guard structures and instability in the excavations. One of the main reasons for not paying enough attention to lateral restraints in excavation projects is the use of two-dimensional flat strain analysis in the design process. In these analyzes, the forces perpendicular to the plane are not calculated, so the design of lateral restraints is based solely on the designer's experience. In this paper, by modeling a excavation project located in the city of Tabriz (as a case study) in three two-dimensional plexus software, the results and the effects of lateral bracing of the truss guard structure are compared. And a ۷ m high hollow wall investigates the effects of lateral bracing on the reliability coefficients and displacements that occur during service conditions. The results indicate that the use of lateral restraints increases their stability reliability coefficients with the truss guard structure and leads to a reduction in deformation of service conditions.