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International Concrete Abstracts Portal

Showing 1-5 of 13 Abstracts search results

Document: 

SP321-06

Date: 

September 29, 2017

Author(s):

Aikaterini S. Genikomsou and Maria A. Polak

Publication:

Symposium Papers

Volume:

321

Abstract:

Three-dimensional (3-D) finite element analysis (FEA) is considered to examine previously tested and analyzed under static loading reinforced concrete slabs using the FEA software ABAQUS. Four interior reinforced concrete slab-column connections are presented; one slab is without shear reinforcement (SB1) and the other slabs are with shear bolts (SB2, SB3 and SB4) which differ in the amount of the shear bolts. The coupled plasticity damaged model previously calibrated is considered for modeling the concrete. In this research, parametric studies are presented considering different amount and placement of the shear bolts. The adopted FEA model is used to analyze and investigate the failure modes and loads and the crack patterns of the shear reinforced slab-column connections. Finally, the numerical results obtained from the parametric studies are compared to the current design code predictions.


Document: 

SP321-01

Date: 

September 29, 2017

Author(s):

Eva O. L. Lantsoght, Cor van der Veen, and Ane de Boer

Publication:

Symposium Papers

Volume:

321

Abstract:

Most methods for the design and analysis of reinforced concrete slabs for punching are based on experiments on slab-column connections, reflecting the situation in building slabs. Slab-column connections with unbalanced moments have also been studied in the past. Experiments indicate that the accuracy of models for asymmetrically loaded slabs is lower than for symmetrically loaded slabs. In this paper, the difference in accuracy between test predictions for symmetrically and asymmetrically loaded slabs is tackled. A plastic model, the Extended Strip Model, is proposed. The results of maximum loads according to this model are compared to experimental results of symmetrically and asymmetrically loaded slabs. The comparison between the proposed Extended Strip Model and the experimental results shows that the model has a consistent performance for both symmetrically and asymmetrically loaded slabs. Moreover, the model has as an advantage that it combines the failure modes of flexure, shear and punching. The proposed model can be used for the analysis of slabs. In particular, it can be used for the assessment of existing slab bridges subjected to concentrated live loads.


Document: 

SP321-02

Date: 

September 29, 2017

Author(s):

Georgios P. Balomenos, Aikaterini S. Genikomsou, Mahesh D. Pandey, and Maria A. Polak

Publication:

Symposium Papers

Volume:

321

Abstract:

Four interior reinforced concrete flat slabs are analyzed deterministically using the finite element analysis (FEA) program ABAQUS. Using this verified FEA model, probabilistic FEA is performed considering uncertain material properties. Probabilistic FEA is executed using a new variance based method, namely, multiplicative dimensional reduction method (M-DRM). M-DRM is selected because it overcomes the computational cost limitation, which can be a barrier for these types of analyses; it provides the probability distribution of any structural response, e.g., distribution of punching shear strength; it conducts sensitivity analysis without requiring any further execution of the FEA code. M-DRM is automated in ABAQUS using python programing. First, this study examines how material uncertainty impacts the structural response of interior flat slabs, in terms of ultimate load and ultimate displacement. Then, sensitivity analysis is performed in order to prioritize the most influential input random variables with respect to these structural responses. Finally, probability distribution of the punching shear resistance is also derived, using the design equations from the American code (ACI 318) and Eurocode 2 (EC2), in order to examine the degree of conservatism associated with the current design practices.


Document: 

SP321-09

Date: 

September 29, 2017

Author(s):

Johannes Furche, Carsten Siburg, and Ulrich Bauermeister

Publication:

Symposium Papers

Volume:

321

Abstract:

Lattice girders consist of longitudinal reinforcing bars which are connected to vertical or inclined struts by welding. Due to the great stiffness of the anchorage of the struts, this kind of reinforcement works well as shear reinforcement also in two way span flat slabs. The experience with different kinds of girders as punching shear reinforcement led to an optimized girder shape. This highly effective girder was tested in full scale tests to obtain a European Technical Approval based on the European design code Eurocode 2. These tests are described in this paper. The results are evaluated according to the American design rules of ACI 318-14 too. The punching shear resistance of slabs with this special lattice punching shear reinforcement is compared with the resistance when using other reinforcement.


Document: 

SP321-05

Date: 

September 29, 2017

Author(s):

Bradley Foust and Theodor Krauthammer

Publication:

Symposium Papers

Volume:

321

Abstract:

The boundary conditions at the supports of reinforced concrete slabs, specifically the amount of lateral and rotational restraint, dictate how they respond to particular loads. Membrane (in-plane) forces are present in slabs when their boundaries are sufficiently stiff, therefore restricting the slabs from lateral translations in addition to rotations. Increases in compressive strength and ductility in ultra-high-performance concrete (UHPC) introduce additional strength enhancement not present in Normal-Strength Concrete (NSC).

Ten reinforced concrete slabs were quasi-statically tested in a static water chamber that allowed hydrostatic forces to be utilized as a loading technique on the slab. Of the 10 slabs, 4 were simply supported, and the remaining 6 were rigidly restrained. The load-deformation responses of laterally restrained slabs were then compared to those of simply-supported slabs to determine the enhancement due to the boundary conditions (i.e., compression membrane action). The results of these experiments were then compared to the results of response calculations based on plastic theory.

Valuable data on rigidly-restrained UHPC slab response were obtained from the experiments. The experimental results were compared to the results of the associated numerical analyses. Existing plastic theory should be used with caution when calculating the ultimate resistance of UHPC slabs. The experimental and numerical results showed that UHPC slabs with sufficiently rigid boundary conditions have a static resistance two-and-a-half-times greater than the traditional yield-line theory resistance for UHPC slabs due to compressive membrane effects.


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