Residual Strength Prediction Based on Size Effect of Cracked Concrete Members

2021 ◽  
pp. 1-24
Author(s):  
Ragip Ince ◽  
Cenk Fenerli
Keyword(s):  
Fracture Mechanics ◽  
Size Effect ◽  
Residual Strength ◽  
Experimental Studies ◽  
Test Results ◽  
Structural Members ◽  
Cracked Concrete ◽  
Concrete Members ◽  
Peak Loads ◽  
Nominal Strength

In engineering materials, defects, such as cracks, may occur during production and/or due to various reasons. One of the aims of fracture mechanics is to determine the fracture toughness-based residual strength of structural members with cracks. A quasi-brittle material, such as concrete or rock, may include certain defects, such as voids and cracks, even before being exposed to loads. Experimental analyses on concrete members indicated that specimens’ nominal strength values were decreased as their sizes increased while specimen geometry is the same. In fracture mechanics, this condition was defined as the “size effect” in both concrete and reinforced concrete units. In the literature, numerous theoretical and experimental studies were conducted on beams while compact split-tension specimens, particularly notched ones are limited. In this study, six series of notched beams with three different sizes and notched square prismatic specimens with four different sizes were tested. According to the test results, the peak loads were analyzed by using the fundamental theorem of the modified size effect law. In conclusion, two formulae were proposed to predict the flexural strength and the splitting strength of quasi-brittle bodies with cracks.

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF THE EFFECT OF SIZE IN POST-TENSIONED CONCRETE DECK SLABS

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Sana Amir ◽  
Cor van der Veen ◽  
Ane de Boer
Keyword(s):  
Size Effect ◽  
Precast Concrete ◽  
Experimental Studies ◽  
Punching Shear ◽  
Small Scale ◽  
Size Factor ◽  
Scaled Model ◽  
Nominal Strength ◽  
Deck Slabs ◽  
Post Tensioned

It is widely known that as the structure of the size increases, its nominal strength decreases. In this paper, the effect of size on punching shear has been quantified for transversely post-tensioned deck slabs cast between flanges of precast concrete girders. A 1:2 scaled model of the bridge was constructed in the laboratory, and experimental and numerical analyses were carried out. However, in order to apply these results on a real bridge, simply using the geometrical scale factors is not sufficient and a structural size effect has to be taken into account. Since a full-scale experimental study was not possible due to the costs involved, a numerical approach using finite element analysis software package TNO DIANA was used to model both the prototype and the real bridge, and a comparison was made to estimate the effect of size on the bearing capacity. It was found that increasing the transverse prestressing level had a positive effect on the punching shear strength of the deck slab. Furthermore, a lower size effect was observed with higher transverse prestressing levels. It is concluded that if a suitable size factor is used, either numerical or small-scale experimental studies can be reasonably used to investigate existing structures.

Experimental Research on Crack Width of Retard-Bonded Partially Prestressed Concrete Beams

2013 ◽  
Vol 639-640 ◽  
pp. 211-215 ◽  
Author(s):  
Xin Feng ◽  
Xian Yan Zhou
Keyword(s):  
Experimental Research ◽  
Prestressed Concrete ◽  
Crack Width ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Test Results ◽  
Paper Test ◽  
Concrete Members ◽  
Maximum Crack ◽  
The Relationship

Retard-bonded prestressed concrete which has appeared in recent twenty years is a new and distinctive prestressed system. For the research on mechanical behavior and service property of retard-bonded prestressed concrete members, retard-bonded prestressed strands were made by manual work in this paper. Experimental research and theoretical analysis of three retard-bonded partially prestressed concrete T-beams were carried out under static loadings. The law of crack development and distribution both with the relationship between load and maximum crack width were studied in the paper. Test results were contrasted with experimental studies of two traditional partially prestressed concrete T-beams, and the characters and merits of retard-bonded partially prestressed concrete T-beams were obtained. It provides theoretical reference for the actual project application of the new retard-bonded prestressed concrete system.

Size Effect on Compressive Strength of Sandwich Panels with Fracture of Woven Laminate Facesheet

2005 ◽  
Vol 128 (2) ◽  
pp. 169-174 ◽  
Author(s):  
John Bayldon ◽  
Zdeněk P. Bažant ◽  
Isaac M. Daniel ◽  
Qiang Yu
Keyword(s):  
Size Effect ◽  
Kink Band ◽  
Test Results ◽  
Nominal Strength ◽  
Closed Cell ◽  
Effect Theory ◽  
The Mean ◽  
Sandwich Core ◽  
Testing Range ◽  
Weibull Theory

Prismatic sandwich specimens of various sizes, geometrically scaled in the ratio 1:2:4:8, are subjected to eccentric axial compression and tested to failure. The sandwich core consists of a closed-cell polyvinyl chloride foam, and the facesheets are woven glass-epoxy laminates, scaled by increasing the number of plies. The test results reveal a size effect on the mean nominal strength, which is strong enough to require consideration in design. The size effect observed is fitted with the size effect law of the energetic (deterministic) size effect theory. However, because of inevitable scatter and limited testing range, the precise form of the energetic size effect law to describe the test results is not unambiguous. The Weibull-type statistical size effect on the mean strength is ruled out because the specimens had small notches which caused the failure to occur in only one place in the specimen, and also because the observed failure mode was kink band propagation, previously shown to cause energetic size effect. Various fallacies in previous applications of Weibull theory to composites are also pointed out.

Size Effect on Strength of Bi-Material Joints of Steel With Fiber-Polymer Composite

2008 ◽  
Author(s):  
Zdeneˇk P. Bazˇant ◽  
Jia-Liang Le ◽  
Ferhun C. Caner ◽  
Qiang Yu
Keyword(s):  
Fracture Mechanics ◽  
Size Effect ◽  
Experimental Studies ◽  
Strength Criterion ◽  
Energy Criterion ◽  
Composite Joints ◽  
Metal Composite ◽  
Singular Stress ◽  
Hybrid Joint ◽  
Large Size

Metal-composite joints between steel ribs and advanced fiber-polymer composites are an effective structural system for hybrid ship hulls. Similar joints are of interest for fuel-efficient aircraft. The current designs of such joints are generally based on the strength criterion, which ignores fracture mechanics. Aimed at an efficient and reliable design, this study investigates the size effect on the strength of these joints theoretically, numerically and experimentally. The analytical formulation of the size effect is asymptotically anchored at the large-size limit in linear elastic fracture mechanics (LEFM). The bi-material corner of the joint is shown to have a singular stress field with complex singularity. The strength of the joint is determined by the energy criterion for the macrocrack initiation at the corner, from which the large-size asymptote of the size effect law has been derived. A general approximate size effect law, spanning all sizes and various joint angles, is further derived via asymptotic matching. Numerical analysis with cohesive fracture model is used to design the experiments. Experimental studies involve the testing of geometrically similar hybrid joint specimens with the size ratio of 1 : 4 : 12. The analytical, numerical and experimental studies all indicate that the strength of bimaterial metal-composite joints is subjected to a strong size effect.

Scaling of Sea Ice Fracture—Part I: Vertical Penetration

2001 ◽  
Vol 69 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Z. P. Bazˇant
Keyword(s):  
Fracture Mechanics ◽  
Sea Ice ◽  
Size Effect ◽  
Large Scale ◽  
Load Capacity ◽  
Field Tests ◽  
Material Strength ◽  
In Situ Tests ◽  
Vertical Loading ◽  
Nominal Strength

Based on the premise that large-scale failure of sea ice is governed by fracture mechanics, recently validated by Dempsey’s in situ tests of fracture specimens of a record-breaking size, this two-part study applies fracture mechanics and asymptotic approach to obtain approximate explicit formulas for the size effect in two fundamental problems. In the present Part I, the load capacity of a floating ice plate subjected to vertical load is determined, and in Part II, which follows, the horizontal force exerted by an ice plate moving against a fixed structure is analyzed in a similar manner. The resulting formulas for vertical loading agree with previous sophisticated numerical fracture simulations as well with the limited field tests of vertical penetration that exist. The results contrast with the classical predictions of material strength or plasticity theories, which in general exhibit no size effect on the nominal strength of the structure.

Test Study on Size Effect of Flexural Performance of RC Free Beams

2012 ◽  
Vol 446-449 ◽  
pp. 3385-3389
Author(s):  
Hong Yu Zhou ◽  
Xiu Li Du ◽  
Zhen Bao Li ◽  
Wen Jing Wang
Keyword(s):  
Reinforced Concrete ◽  
Size Effect ◽  
Experimental Studies ◽  
Internal Force ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Test Results ◽  
Flexural Performance ◽  
Test Study ◽  
Practical Engineering

Experimental studies on size effect of flexural behavior of reinforced concrete beams are not carried out fully. Standard values are based on test results of small-size components, which are different from large-size components in practical engineering. For size effect on quasi-brittle materials such as concrete, related researches have been carried out for many years, but related test study combined with concrete structures or components are not sufficient. This article is based on experimental study of 13 reinforced concrete free beams, obtaining test data during different loading stage, such as carrying capacity, deflection, steel and concrete strain etc. Test results show that size effect of flexural behavior of RC free beams is mainly reflected in reinforcement yielding stage and concrete crushing stage. The negative size effect due to concrete material is not significant. Yet internal force arm and longitudinal reinforcement have a positive size effect on flexural behavior, strength and ductility reserves show a growing trend with specimen size increasing. The safety of calculation theory of bearing capacity in code is verified indirectly.

Strengthening of Prefab Slab using Fiber Reinforce Composites

2017 ◽  
Vol MCSP2017 (01) ◽  
pp. 27-29
Author(s):  
Gitanjali Biswal ◽  
Manoj Kumar Rath ◽  
Sagarika Panda
Keyword(s):  
Glass Fiber ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Structural Members ◽  
Load Bearing ◽  
Concrete Members ◽  
Shrinkage Cracks ◽  
Glass Fiber Reinforced ◽  
New Material ◽  
Fiber Reinforce

The main objective of using strengthening of pre fab slab by wraping with frp to to make it more durable during shock as a modification for the prevention of shrinkage cracks. The aim of research is to strengthening of Pre-fab structures slab using glass fiber reinforced composites. Slabs will act as structural members; provide a sensible application for the new material because they can be casted as load bearing and non-load bearing concrete members.

Research on Static Load Tests of Damaged Bridge Strengthened with Pre-Stressed HFRP

2014 ◽  
Vol 1079-1080 ◽  
pp. 258-265
Author(s):  
Chen Ning Cai ◽  
Shan He ◽  
Li Na Liu ◽  
Shi Kun Ou
Keyword(s):  
Static Load ◽  
Flexural Rigidity ◽  
Fiber Reinforced Polymer ◽  
Test Results ◽  
Structural Members ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Load Tests

Thispaper presents an experimental study to strengthen an existing bridge usingpre-stressed carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer(GFRP) materials. The method using pre-stressed hybrid fiber reinforced polymer(HFRP) to strengthened structural members is an emerging pre-stressed strengtheningtechnology. In this study, experimental data selected from result of staticloading test conducted to hollow slabs with CFRP/GFRP has been compared with specimenswithout strengthening. Test results showed that the strengthening methoddeveloped in this study could effectively reduce the stress in hollow slab,improving the flexural rigidity and inhibiting the concrete from fracture.

scholarly journals Numerical and Experimental Investigation on Concrete Splitting Failure of Anchor Channels

CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 502-522
Author(s):  
Anton Bogdanić ◽  
Daniele Casucci ◽  
Joško Ožbolt
Keyword(s):  
Construction Industry ◽  
Failure Mode ◽  
Current Trend ◽  
The United States ◽  
Embedment Depth ◽  
Test Results ◽  
Concrete Members ◽  
Splitting Failure ◽  
Edge Distance ◽  
Numerical Parametric Study

Concrete splitting failure due to tension load can occur when fastening systems are located close to an edge or corner of a concrete member, especially in thin members. This failure mode has not been extensively investigated for anchor channels. Given the current trend in the construction industry towards more slender concrete members, this failure mode will become more and more relevant. In addition, significantly different design rules in the United States and Europe indicate the need for harmonization between codes. Therefore, an extensive numerical parametric study was carried out to evaluate the influence of member thickness, edge distance, and anchor spacing on the capacity of anchor channels in uncracked and unreinforced concrete members. One of the main findings was that the characteristic edge distance depends on the member thickness and can be larger than 3hef (hef = embedment depth) for thin members. Based on the numerical and experimental test results, modifications of the design recommendations for the splitting failure mode are proposed. Overall, the authors recommend performing the splitting verification separately from the concrete breakout to design anchor channels in thin members more accurately.

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