Concrete Properties for Long-Span Post-Tensioned Slabs

Szydłowski, Rafał

doi:10.4028/www.scientific.net/msf.926.122

Cited by 3 publications

(3 citation statements)

References 4 publications

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“…Low creep guarantees low deflection increments over time. Although this concrete is characterized by a lower modulus of elasticity compared to normal weight concrete (the values obtained after 28 days were 22.1 and 22.4 GPa), several computational analyses [ 4 , 12 , 13 ] and in-situ tests [ 12 , 37 ] have shown that, with proper prestressing, the lowered modulus of elasticity is not problematic and does not lead to an increase in deflections.…”

Section: Discussionmentioning

confidence: 99%

Experimental Evaluation of Shrinkage, Creep and Prestress Losses in Lightweight Aggregate Concrete with Sintered Fly Ash

Szydłowski

Łabuzek

2021

Materials

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The paper presents the experimental results of shrinkage, creep, and prestress loss in concrete with lightweight aggregate obtained by sintering of fly ash. Two concrete mixtures with different proportions of components were tested. Concrete with a density of 1810 and 1820 kg/m3, and a 28-day strength of 56.9 and 58.4 MPa was obtained. Shrinkage and creep were tested on 150 × 250 × 1000 mm3 beams. Creep was tested under prestressing load for 539 days and concrete shrinkage for 900 days. The measurement results were compared with the calculations carried out according to the Eurocode 2 as well as with the results of other research. A very low creep coefficient and lower shrinkage in relation to the calculation results and the results of other research were found. It was also revealed that there is a clear correlation between shrinkage and creep, and the amount of water in the concrete. The value of the creep coefficient during the load holding period was 0.610 and 0.537, which is 56.0 and 49.3% of the value determined from the standard. The prestressing losses in the analyzed period amounted to an average of 13.0%. Based on the obtained test results, it was found that the tested lightweight aggregate concrete is well suited for prestressed concrete structures. Shrinkage was not greater than that calculated for normal weight concrete of a similar strength class, which will not result in increased loss of prestress. Low creep guarantees low deflection increments over time.

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Section: Discussionmentioning

confidence: 99%

Experimental Evaluation of Shrinkage, Creep and Prestress Losses in Lightweight Aggregate Concrete with Sintered Fly Ash

Szydłowski

Łabuzek

2021

Materials

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“…With the beginning of the 20th century, structural thought developed and ceilings with concrete slabs on steel beams and ceilings with monolithic reinforced concrete beams appeared. The constant search for new structural solutions to meet innovative architectural visions led to the development of monolithic prestressed floors [ 4 , 5 , 6 ]. Due to the greater strength of the floors made of these materials, the design and weight was modified to meet the needs of the new large-scale spaces.…”

Section: Introductionmentioning

confidence: 99%

Optimal Design of Bubble Deck Concrete Slabs: Sensitivity Analysis and Numerical Homogenization

2023

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The use of layered or hollow floors in the construction of buildings obviously reduces the self-weight of the slab, and their design requires some expertise. In the present work, a sensitivity analysis and numerical homogenization were used to select the most important characteristics of bubble deck floors that have a direct or indirect impact on their load capacity. From the extensive case study, conclusions were drawn regarding the optimal selection of geometry, materials, and the arrangement and size of air voids in such a way as to ensure high stiffness of the cross-section and at the same time maximally reduce the self-weight of the slabs. The conducted analyses showed that the height of the slab and the geometry of the voids had the greatest impact on the load-bearing capacity. The concrete class and reinforcement used are of secondary importance in the context of changes in load-bearing capacity. Both the type of steel and the amount of reinforcement has a rather small or negligible influence on the bubble deck stab stiffness. Of course, the geometry of the voids and their arrangement and shape have the greatest influence on the drop in the self-weight of the floor slabs. Based on the presented results of the sensitivity analysis combined with numerical homogenization, a set of the most important design parameters was ordered and selected for use in the optimization procedure.

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“…These forces act counter to the weight in the centre of the floor, thus reducing the long-term creep deformation of the concrete. It should also be noted that prestressing minimizes the possibility of cracking and fracture in the concrete, thus sealing the floor and protecting the reinforcement against the corrosive effects of the external environment [31,32,34].…”

Section: Introductionmentioning

confidence: 99%

Application of the Generalized Nonlinear Constitutive Law to Hollow-Core Slabs

Staszak¹,

Garbowski²,

Ksit³

2021

Preprint

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The non-linear analysis of hollow-core concrete slabs requires the use of advanced numerical techniques, proper constitutive models both for concrete and steel as well as particular computational skills. If prestressing, cracking, crack opening, material softening, etc. are also to be taken into account, then the computational task can far exceed the capabilities of an ordinary engineer. In order for the calculations to be carried out in a traditional design office, simplified calculation methods are needed. Preferably based on the linear finite element (FE) method with a simple approach that takes into account material nonlinearities. In this paper the simplified analysis of hollow-core slabs based on the generalized nonlinear constitutive law is presented. In the proposed method a simple decomposition of the traditional iterative linear finite element analysis and the non-linear algebraic analysis of the plate cross-section is used. Through independent analysis of the plate cross-section in different deformation states, a degraded plate stiffness can be obtained, which allows iterative update of displacements and rotations in the nodes of the FE model. Which in turn allows to update the deformation state and then correct translations and rotations in the nodes again. The results obtained from the full detailed 3D nonlinear FEM model and from the proposed approach are compared for different slab cross-sections. The obtained results from both models are consistent.

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Concrete Properties for Long-Span Post-Tensioned Slabs

Cited by 3 publications

References 4 publications

Experimental Evaluation of Shrinkage, Creep and Prestress Losses in Lightweight Aggregate Concrete with Sintered Fly Ash

Experimental Evaluation of Shrinkage, Creep and Prestress Losses in Lightweight Aggregate Concrete with Sintered Fly Ash

Optimal Design of Bubble Deck Concrete Slabs: Sensitivity Analysis and Numerical Homogenization

Application of the Generalized Nonlinear Constitutive Law to Hollow-Core Slabs

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