Investigation of influence of concrete material models on cyclic inelastic response of a concrete filled composite plate shear wall

A previously benchmarked finite element model of a previously tested composite plate shear wall-concrete filled (C-PSW/CF) was used to investigate the influence of three concrete material models on in-plane cyclic inelastic wall response, using LS-Dyna. The concrete material models considered were the Winfrith, KCC and CSCM, all available in LS-Dyna. Wall moment hysteresis, using the three concrete material models, were obtained and compared. Individual contribution of the steel and concrete to total base moment was investigated for each wall with the three concrete material models. The numerical results obtained using the KCC and CSCM were compared against the benchmarked results obtained using the Winfrith concrete material model. Moment contribution of the steel web and the steel boundary on total base moment of the steel part of the wall and moment contribution of the concrete web and concrete boundary on total base moment of the concrete part of the wall were individually investigated. The wall models with the KCC and CSCM concrete models were observed to cannot capture wall pinching which was captured by the Winfrith concrete model. The wall strength was overpredicted by the CSCM concrete model and predicted reasonably by the KCC concrete model. Average axial stress distribution of the infill concrete was obtained to investigate wall neutral axis and the maximum attained concrete strength using the three concrete models. Concrete axial stress distribution showed some level of confinement for the concrete models considered.

Experimental Investigation of Steel Plate Shear Walls under Shear-Compression Interaction

Four scaled one-storey single-bay steel plate shear wall (SPSW) specimens with unstiffened panels were tested to determine their behaviour under cyclic loadings. The shear walls had moment-resisting beam-to-column connections. Four different vertical loads, i.e., 300 kN, 600 kN, 900 kN, and 1200 kN, representing the gravity load of the upper storeys were applied at the top of the boundary columns through a force distribution beam. A horizontal cyclic load was then applied at the top of the specimens. The specimen behaviour, envelope curves, axial stress distribution of the infill steel plate, and shear capacity were analyzed. The axial stress distribution and envelope curves were compared with the values predicted using an analytical model available in the literature.

Pullout Test on Fully Grouted Bolt Sheathed by Different Length of Segmented Steel Tubes

In order to evaluate the anchorage performance of rebar bolt sheathed by different length of segmented steel tubes, a total of eight groups of pullout tests were conducted in this study. The steel tubes, segmented by 5 cm, 7 cm, 9 cm, 10 cm, and 15 cm, utilized in current study were bonded together by a high performance two-component adhesive to form standard 30 cm long steel tube. Unlike axial stress distribution in bolt, the axial stress distribution in steel tube showed exponential decrease trend from tube-clamp end to bolt-clamp end; thus a series of interesting results were observed. For instance, the sequence for segments detachment had its specific order of priority; the failure form of bolting system, the load oscillation characteristics, and the final displacement were highly determined by the length of the last segment, namely, the one fixed by clamp of testing machine. Moreover, the load-displacement relationship for some particular samples was further investigated from the perspective of energy transformation, and the disequilibrium extension of interfacial decoupling was also discussed. This paper, from a relatively idealized perspective, presents a laboratorial solution to interpret the mechanical performance of the bolt installed in layered strata; so far at least it demonstrates that a bolt installed in comparatively thicker layer of strata can last more durable and stable.

Analytical and Numerical Evaluation of the Axial Stress Distribution of Two Soft-Packed Stuffing-Box Configurations

Stuffing-box packed valves which confine high-pressure fluids are often subjected to leakage failure. The lack of a design procedure and the vulnerability of packing ring sealing materials to withstand different operating conditions are the root cause of the problem. The sealing performance of valves with packed stuffing-box depends on the ability of the assembly to maintain a minimum threshold contact pressure between the packing and the stem and the packing and the housing throughout service operation. The distribution of the contact stresses in the packing materials is a key parameter to efficient sealing performance. This study presents a contact stress modeling study of two different design configurations that are helpful to produce a uniform distribution of the contact stress. The first model is based on the introduction of a variable gap between the packing and the side walls. The second model is based on a multistage loading of the packing rings. The two developed analytical models are validated by comparison with the numerical simulation using FE method and the results show a good agreement. The two design configurations can be used to improve valve sealing performance.

Study on the Interfacial Shear Stress Distribution Characteristics of Geotechnical Prestressed Anchorage Structure

The ultimate bearing capacity of prestressed anchorage structure is directly related to the interfacial shear stress distribution characteristics of the inner anchorage section. Firstly, the axial stress distribution characteristics of the inner anchorage section for the geotechnical prestressed anchorage structure under tensile load are further studied by indoor similarity model test, and the corresponding fitting formula is established. Based on this result and the force equilibrium conditions of rod body’s micro-segment, the rod body interfacial shear stress distribution characteristics formula is also derived, which fits well with the results of the indoor model test. The research achievements have important significance for the further study on stress distribution characteristics of the inner anchorage section.