RC two-way slabs strengthened with CFRP strips: experimental study and a limit analysis approach

Voided slab systems were developed using segmented void formers such as spherical or oval plastic balls for two-way slab applications. This type of slab is expected to behave like a general two-way reinforced concrete slab because it has segmented voids, rather than the continuous voids of hollow core slabs. However, the structural behaviors of two-way voided slabs with segmented voids have not been clearly verified. Therefore, this paper analyzes the possibility of applying a donut-type two-way voided slab, which was investigated with a 12-point two-way bending test focused on global behaviors, including its load bearing capacity, flexural stiffness, ductility, deflection, and load distribution. In addition, the design method of a donut-type two-way voided slab was reviewed through the yield line method. The test results showed that one donut-type two-way voided slab acted like a conventional two-way reinforced concrete slab with the load distributed evenly between the different directions; however, another donut-type two-way voided slab with different characteristics showed uneven load distribution with different crack patterns. In addition, the yield line method could predict the load bearing capacities of the donut-type voided slabs with approximately 95% accuracy.

/pdf/two-way-flexural-behavior-of-donut-type-voided-slabs-1zv9vxlq67.pdf

Two-Way Flexural Behavior of Donut-Type Voided Slabs

The paper proposes an efficient numerical method, namely, the elastic modulus reduction method (EMRM) to calculate lower-bound limit loads of thin plate and shell structures. To determine the elastic modulus adjustment parameter q in a rational way, the precisions and convergent properties of four different strategies of elastic modulus adjustment (SEMAs) combined with the EMRM are investigated. Furthermore, to take into consideration the plastic resistances as well as the internal forces in the processes of elastic modulus adjustment, the element bearing ratio (EBR) of thin plate/shell element is defined as the governing parameter based on the generalised yield criterions. The flexibility and accuracy of the proposed EMRM combined with both the strain energy equilibrium principle (SEEP) and the fixed strain method (FSM) are demonstrated in the numerical example.

Elastic modulus reduction method for limit analysis of thin plate and shell structures

High-performance engineered structural systems are crucial for sustainable development in the field of construction. In our previous research, a novel steel–concrete composite beam with transverse and longitudinal hidden girders exhibited good flexural behavior and desirable ductility. However, there is a dearth of studies on the flexural response of a steel–concrete composite slab voided with thin-walled core boxes. Therefore, in this study, we investigated the overarching flexural mechanism of the proposed structure when subjected to uniform vertical loads. The experimental detection results illustrated that the deflection value of the composite beam was 95.75% less than the GB/T 50152-2012 recommendation. Numerical results further validated this observation. The recorded data from the strain profile at the mid-span of the frame girder indicated that there was a considerable membrane effect, which delayed the strain growth of rebars, yielding appreciable bearing capacity. Thus, two original approaches to predicting the ultimate load of this novel structure are proposed, considering limit analysis using the upper-bound method and the membrane effect, with the latter closely linked to the experimental results. The findings can promote the extensive application of similar sustainable systems and inspire further advancements in advanced engineering structures.

Behavior of a Two-Way Lightweight Steel─Concrete Composite Slab Voided with Thin-Walled Core Boxes towards Sustainable Construction

https://bura.brunel.ac.uk/bitstream/2438/23060/1/FullText.pdf

P.A. Slade

Papers

Numerical and analytical predictions of the limit load of rectangular two way slabs