Seismic reliability evaluation of tunnel form (box‐type) RC structures under the accidental torsion

Abstract

In the tunnel form (box‐type) structural system, walls arrangement and mass distribution have important effect on the interactions of thinner shear walls and slab configurations. In the other words, despite the regularity of these buildings as well as symmetry in wall arrangement and mass distribution, the first mode of structural behavior in many cases is twisting. This characteristic is limited to the flexible torsional buildings, which are often sensitive to the mass eccentricity and rotational components of earthquake. According to the available guidelines for design and construction of tunnel form systems and emphasizing on regularity of these structural systems, it seems that the most probable mass irregularity of this type of structures is asymmetric distribution of live loads during service life. Therefore, in this paper, seismic behavior of box‐type (tunnel form) buildings is evaluated under the accidental torsion caused by asymmetric distribution of mass in stories. The incremental nonlinear dynamic analysis is used for this purpose. Despite the asymmetric distribution of mass in plan, the results demonstrate high capacity and appropriate seismic behavior of the tunnel form system. Therefore, an eccentricity equal to 10% of the plan dimension does not change the building performance level, which is higher than the immediate occupancy level under the design and maximum probable earthquake hazard levels.

A low computational cost seismic analyses framework for 3D tunnel-form building structures

“…Several studies have been also performed on the effects of accidental torsions due to eccentricities of centers of mass, strength, or stiffness, on the seismic performance of tunnel-form building structures (Mohsenian and Mortezaei, 2018; Mohsenian et al, 2018, 2021a; Mortezaei and Mohsenian, 2022). In general, the outcomes of these studies indicate that the accidental torsions have no significant influence on the performance level of these systems.…”

Experimental study on seismic performance of steel fiber reinforced concrete wall piers

“…The reinforcing contribution of steel fibers can be mobilized in planar SFRC elements, such as elevated SFRC slabs, as the primary reinforcement 29 . Many studies conducted, in recent years, on the specifications and characteristics of fiber reinforced concrete, including the effects of volume, aspect ratio, geometry, alignment and resistance of fibers 30–44 . Most studies have been focused on concrete technology and structural components such as beams, columns and connections.…”

Estimation of seismic response parameters and capacity of irregular tunnel-form buildings

“…It was shown that the forward directivity can influence the failure modes of tall tunnel-form structures and reduce the reliability of the design. Mohsenian and Mortezaei (2018a) also evaluated the seismic reliability of tunnel-form structures subjected to accidental torsions. According to their results, eccentricity of mass centre by up to 10% of the plan dimension does not considerably affect the performance of these systems.…”