Strength of reinforced concrete footings without transverse reinforcement according to limit analysis

https://repositorium.sdum.uminho.pt/bitstream/1822/45444/1/IJ%28ISI%29_149.pdf

Prediction of the load carrying capacity of elevated steel fibre reinforced concrete slabs

Hybrid reinforced technology (combination of steel reinforcing bars and fibers) can be considered as a competitive alternative to the already existing solutions for the construction of column‐supported flat slabs. Constructed hybrid‐reinforced buildings prove that hybrid solutions have sufficient bearing capacity to maintain structural integrity despite being exposed to high stress levels, thereby providing a beneficial solution in terms of toughness, ductility, and sustainability performance. However, the lack of design‐oriented recommendations based on the accepted limit state format for dealing with both serviceability and ultimate limit states slows down the wider implementation of this technology. Considering the above‐mentioned, this article presents a simplified design‐oriented method that covers the evaluation of the structural response of hybrid reinforced concrete column‐supported flat slabs in terms of flexural strength, cracking, and instantaneous deformations. Two hybrid reinforced alternatives for a given flat slab are studied by means of the proposed approach. Furthermore, a nonlinear finite element analysis is carried out in order to evaluate the effectiveness of the developed simplified method. Based on the achieved results, its suitable accuracy and precision can be pointed out. This outcome may motivate current practitioners to consider hybrid reinforced concrete solutions as a possible alternative during the design of residential and office buildings.

A limit state design approach for hybrid reinforced concrete column‐supported flat slabs

In this study, the yield line method of analysis is used to calculate the ultimate punching capacity of ten full panel, unbonded post-tensioned slabs, six of which were subject to combined vertical and transfer of moment loading. It is found that the method estimates to within 10% the failure loads for cases involving purely vertical loading. However, the predictions for those slabs subjected to moment transfer are not consistent. An important consideration in this regards was the presence or otherwise of ordinary bonded reinforcement at the critical positive moment regions of the slabs. It is suggested that alternative flexural mechanisms of punching failure should be utilized in lieu of yield line theory to obtain reliable estimates of the punching capacity.

On yield line estimates of the punching strength of full panel unbonded post-tensioned flat slabs at internal columns

In spite of the high clear height and the convenient pipeline arrangement, the application of slab–column structures is still limited especially given the development trend of prefabricated steel s...

Numerical study on modular slab–column steel structure based on simplified integrated floor:

A PRIMARY PROBLEM AT SLAB-COLUMN INTERSECTIONS IS THE POSSIBLE PUNCHING FAILURE OF THE SLAB. BY ANALYSIS OF EXPERIMENTAL DATA AVAILABLE IN THE LITERATURE, IT CAN BE SHOWN THAT, IN MANY CASES, THE BENDING RATHER THAN THE SHEAR STRENGTH OF THE SLAB GOVERNS ITS PUNCHING RESISTANCE. YIELD-LINE THEORY WAS USED TO DERIVE EXPRESSIONS FOR THE BENDING-PUNCHING STRENGTH OF UNIFORMLY LOADED SLABS SUPPORTED ON COLUMNS. COLUMNS LOCATED IN THE INTERIOR OF THE SLAB, AT OR NEAR THE BOUNDARY AND AT OR NEAR CORNERS WERE CONSIDERED, AND THE EFFECTS OF VARIOUS PHYSICAL PARAMETERS WERE STUDIED. THE BENDING-PUNCHING STRENGTH PREDICTED BY THE EXPRESSIONS DERIVED WAS COMPARED TO THE SHEAR (PUNCHING) STRENGTH PREDICTED BY THE VERY CONSERVATIVE ACI BUILDING CODE FORMULAS, AND WAS FOUND TO GOVERN IN SOME CASES. LOWER BOUND (ELASTIC) THEORY AND ELASTIC-PLASTIC INCREMENTAL ANALYSIS SOLUTIONS WERE OBTAINED FOR TWO CASES OF COLUMNS NEAR A SLAB BOUNDARY AND ALSO COMPARED WITH THE YIELD-LINE THEORY RESULTS. IT IS CONCLUDED THAT BENDING-PUNCHING FAILURE IS POSSIBLE IN MANY SLABS, AND THEREFORE THIS TYPE OF ANALYSIS SHOULD BE CARRIED OUT FOR SLAB-COLUMN INTERSECTION DESIGNS IN ADDITION TO, IF NOT IN PLACE OF, THE ACI CODE SHEAR ANALYSES. THE GRAPHS PRESENTED COVER THE PRACTICAL RANGES OF THE PHYSICAL VARIABLES. /ACI/

O.P. Dikshit

Papers

Yield line analysis of the punching problem at slab-column intersections

Yield Line Analysis of the Punching Problem at Slab/Column Intersections