Seismic Performance Evaluation of RC Columns Retrofitted by 3D Textile Reinforced Mortars

The paper investigates the seismic performance of rectangular RC columns retrofitted by a newly developed 3D Textile Reinforced Mortar (TRM) panel. The 3D-TRM used in this study consists of two components: self-leveling mortar and 3D textiles. Firstly, the flexural capacity of the 3D-TRM panel was investigated through the four-point flexural test. Secondly, a total of five specimens were constructed and experimentally investigated through static cyclic loading tests with constant axial load. One specimen was a non-seismically designed column without any retrofit, while the others were strengthened with either the 3D-TRM panel or conventional Fiber Reinforced Polymer (FRP) sheets. Experimental results in terms of hysteretic behavior, ductility ratio, and energy dissipation are investigated and compared with the cases of specimens with conventional retrofitting methods and without any retrofit. The maximum lateral force, ductility, stiffness degradation, and energy dissipation of RC columns with 3D-TRM panels were significantly improved compared with the conventional RC column. Therefore, it is concluded that the proposed retrofitting method can improve the seismic performance of non-conforming RC columns.

Experimental investigations into the mechanical performance of glulam dowel-type connections with either bolts or screws as fasteners

Dowel-type connections are the most common connections in glulam structures. Bolts are often used as fasteners for dowel-type connections. However, the clearance between the bolts and the pre-drilled bolt holes leads to low rotational stiffness and insufficient moment-resisting capacity. To achieve better mechanical performance, screws can be used as alternative fasteners for dowel-type connections. In this paper, monotonic and cyclic loading tests were conducted on glulam dowel-type connections with either bolts or screws as fasteners. The failure modes, moment-resisting capacity, ductility ratio, stiffness degradation, and equivalent viscous damping ratio of the specimens were analyzed and reported. Results showed that compared with traditional bolted connections, the screwed connections had larger moment-resisting capacity and better ductility. The hysteretic loops of the screwed connections were plumper, and the pinching effect was gentler compared to those of traditional bolted connections.

Seismic Resistance of Timber Frames with Mud and Stone Infill Walls in a Chinese Traditional Village Dwelling

Traditional Chinese wood residences consist of timber frames with masonry infill walls or other types of infill, representing valuable heritage. A field investigation of traditional village dwellings in northern China consisting of timber frames with mud and stone infill walls was conducted. Their construction characteristics are reported, and static cyclic tests were performed on two full-size wood-stone hybrid walls with different configurations (exterior transverse wall and internal transverse wall) and no openings (doors or windows). Their failure mechanics and seismic capacity, i.e., the strength, stiffness, ductility, and energy dissipation, were investigated. The results are compared with a previous experimental study of two full-size timber frames with the same traditional structure but no infill to determine the effect of the mud and stone infill on the lateral resistance. The experimental results indicate that the stone infill has a critical influence on the lateral performance of traditional village buildings, resulting in a high lateral stiffness, high strength (>20 kN), and a high ductility ratio (>10). An increase in the vertical load leads to an increase in the lateral resistance of the timber frame with infill walls, larger for the internal transverse wall than the external gable wall. The incompatibility of the deformation between the timber frame and stone infill is the main failure reason, resulting in falling stones and collapse with undamaged timber frames. Suggestions are provided for the protection and repair of traditional wood residences in northern China.

Experimental and Numerical Investigation of Light-Wood-Framed Shear Walls Strengthened with Parallel Strand Bamboo Panels

This paper describes experimental and numerical investigations on a new type of strengthened light-wood-framed (LWF) shear wall (SW) that has parallel strand bamboo (PSB) panels at each end. The experiments are divided into two parts: (1) monotonic loading tests of panel-to-frame joints representing different positions along the wall; (2) monotonic loading tests of a group of traditional full-scale SWs and two groups of strengthened walls with nailed or screwed PSB panels. The failure modes, load–displacement curves, ultimate bearing capacity, elastic stiffness, and dissipation are analyzed, and the mechanical properties of panel-to-frame joints and the lateral performance of SWs are discussed. Moreover, nonlinear finite-element analysis shows that the numerical results are in good agreement with the test results. Our findings suggest that using LWF SWs strengthened with nailed PSB panels effectively improves the failure mode and the ductility, stiffness, and dissipation of traditional walls. Using sheathing screws on the PSB panels increases the lateral bearing capacity and the dissipation of the walls, but decreases their ductility ratio. Setting end PSB panels improves the overturning resistance capacity by restricting the uplift of studs. The LWF SWs strengthened with end PSB panels are found to meet the design requirements and reduce construction costs.

Flexural Behaviour of Chicken Mesh Ferrocement Laminates with Partial Replacement of Fine Aggregate by Steel Slag

Bending tests were conducted on ferrocement laminates containing chicken mesh and steel slag. The fundamental goal of the examination was to investigate the effects of partial substitution of fine aggregate by steel slag in cement mortar combining chicken mesh of different volume fractions as reinforcement in thin ferrocement laminates. The following variables were investigated: (a) volume fraction of chicken mesh as 0.94%, 1.88%, 2.82%, and 3.77% and (b) level of steel slag substitution from 0% to 50% by weight fine aggregate. Results show that ferrocement laminates with chicken mesh of volume fractions of 3.77% and 30% substitution of fine aggregate with steel slag display better performance in terms of load deflection behaviour, first crack load, ultimate load, energy absorption, and ductility ratio when related with other specimens. An analytical model has been proposed to predict the ultimate moment carrying capacity of ferrocement laminates under flexure to validate the experimental results.

A Study on the Flexural Behaviour of Geopolymer Lightweight Eco-Friendly Concrete Using Coconut Shell as Coarse Aggregate

This paper presents the flexural behaviour of concrete containing ground granulated blast furnace slag (GGBS) as a binder, manufactured sand (M-sand) as a fine aggregate, and coconut shell (CS) and crushed stone aggregate (CSA) as coarse aggregates. Alkaline activator sodium hydroxide with 10 molarity and sodium silicate were used in a weighing proportion of 1 : 2.5 to produce structural grade concrete. Out of 12 beams cast, 6 were used to study geopolymer coconut shell concrete (GPCSC) beam behaviour and 6 were used to study geopolymer conventional concrete (GPCC) beam behaviour. Data presented include cracking behaviour, ultimate moment capacitates, deflection behaviour, ductility ratio, and end rotation of the beam. Laboratory investigations show encouraging results, and it can be summarized that coconut shell has good potential as a coarse aggregate for the production of structural grade geopolymer lightweight coconut shell concrete.

Experimental/Numerical Evaluation of Steel Trapezoidal Corrugated Infill Panels with an Opening

This paper investigates the influence of an opening in the infill steel plate on the behavior of steel trapezoidal corrugated infill panels. Two specimens of steel trapezoidal corrugated shear walls were constructed and tested under cyclic loading. One specimen had a single rectangular opening, while the other one had two rectangular openings. In addition, the percentage of opening in both specimens was 18%. The initial stiffness, ultimate strength, ductility ratio and energy dissipation capacity of the two tested specimens are compared to a specimen without opening. The experimental results indicate that the existence of an opening has the greatest effect on the initial stiffness of the corrugated steel infill panels. In addition, the experimental results reveal that the structural performance of the specimen with two openings is improved in some areas compared to the specimen with one opening. To that end, the energy dissipation capacity of the specimen with two openings is obtained larger than the specimen with one opening. Furthermore, a number of numerical analyses were performed. The numerical results show that with increasing the thickness of the infill plate or using stiffeners around the opening, the ultimate strength of a corrugated steel infill panel with an opening can be equal to or even more than the ultimate strength of that panel without an opening.

Experimental Investigation on Composite Deck Slab Made of Cold-Formed Profiled Steel Sheeting

An experimental investigation is performed on various cold-formed profiled sheets to study the connection behavior of composite deck slab actions using bolted shear connectors. Various profiles like dovetailed (or) re-entrant profiles, rectangular profiles and trapezoidal profiles are used in the present investigation. This experimental investigation deals with the evaluation of various parameters such as the ultimate load carrying capacity versus deflection, load versus slip, ductility ratio, strain energy and modes of failure in composite slab specimens with varying profiles. From the test results the performance of dovetailed profiled composite slabs’ resistance is significantly higher than the other two profiled composite deck slabs.