scholarly journals Service Life Prediction of Precast Concrete Structures Exposed to Chloride Environment

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Dawei Zhang ◽  
Yu Zeng ◽  
Mingshan Fang ◽  
Weiliang Jin
Keyword(s):  
Shear Failure ◽  
Precast Concrete ◽  
Probability Model ◽  
Limit State ◽  
Concrete Structures ◽  
Seismic Load ◽  
Ultimate Limit State ◽  
Interface Shear ◽  
Serviceability Limit State ◽  
Corrosion Initiation

Chloride-induced corrosion is widely accepted as one of the primary causes of premature deterioration for concrete structures in marine or deicing salt environment. For precast concrete (PC) structures, such durability problems may even be severer because defects in joint areas, e.g., cracks caused by grout shrinkage and improper construction, can accelerate chloride ion transportation process and may cause the interface shear failure when subjected to seismic load. By applying the path probability model (PPM) and reliability theory, a probabilistic framework was proposed to predict three limit states of PC structures, including corrosion initiation, serviceability limit state, and ultimate limit state. Using Monte Carlo simulation, a beam-to-column joint was further analyzed to illustrate the differences between PC structures and those cast in situ. The analysis indicates that corrosion initiation and serviceability limit state are sensitive to chloride diffusivity at connection area, and the higher pitting factor can significantly influence the bearing capacities of PC structures.

scholarly journals Reinforced concrete structures strengthened with CFRP (ACI x FIB) - Recommendations for bending design criteria

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Igor Del Gaudio Orlando ◽  
Túlio Nogueira Bittencourt ◽  
Leila Cristina Meneghetti
Keyword(s):  
Reinforced Concrete ◽  
Limit State ◽  
Concrete Structures ◽  
Experimental Tests ◽  
Fiber Reinforced Polymers ◽  
Design Criteria ◽  
Ultimate Limit State ◽  
Reinforced Concrete Structures ◽  
Carbon Fiber Reinforced Polymers ◽  
Model Code

abstract: This work deals with the evaluation of the design criteria and security check (Ultimate Limit State - ULS) of the American (ACI-440.2R, 2017) and European (FIB Model Code, 2010) standards of reinforced concrete structures strengthened with Carbon Fiber Reinforced Polymers (CFRP), by the technique of Externally Bonded Reinforcement (EBR). It is intended to evaluate if, for a given database of 64 experimental tests of beams and slabs, the obtained results respect the safety conditions according to the mentioned standards, to increase the efficiency of this reinforcement technique and to lead to the establishment of regulatory design criteria in Brazil. Results show a conservative match among experimental and theoretical values calculated according to the two guidelines and it is concluded that a future regulation in Brazil on this subject should be based on the FIB Model Code.

Serviceability limit state design of large concrete structures: Impact on reinforcement amounts and consequences of design code ambiguity

2019 ◽  
Vol 201 ◽  
pp. 109816
Author(s):  
Mikael Basteskår ◽  
Morten Engen ◽  
Terje Kanstad ◽  
Håvard Johansen ◽  
Kjell Tore Fosså
Keyword(s):  
Limit State ◽  
Concrete Structures ◽  
Design Code ◽  
Serviceability Limit State ◽  
Limit State Design ◽  
Code Ambiguity

Fatigue and Serviceability Limit State Model Basis for Assessment of Offshore Wind Energy Converters

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
S. Thöns ◽  
M. H. Faber ◽  
W. Rücker
Keyword(s):  
Wind Energy ◽  
Limit State ◽  
Sensitivity Study ◽  
Offshore Wind ◽  
Ultimate Limit State ◽  
Offshore Wind Energy ◽  
Limit States ◽  
Serviceability Limit State ◽  
State Models ◽  
Energy Converters

This paper develops the models for the structural performance of the loading and probabilistic characterization for the fatigue and the serviceability limit states for the support structure of offshore wind energy converters. These models and a sensitivity study are part of a risk based assessment and monitoring framework and will be applied for establishing the “as designed and constructed” reliability as prior information for the assessment and the design of monitoring systems. The constitutive physical equations are introduced in combination with the fatigue and serviceability limit state requirements as the starting point for the development of the structural performance and loading models. With these models introduced in detail, several modeling aspects for both limit states are analyzed. This includes analyses of the influence on the hot spot stresses by applying a contact formulation for the pile guide brace connection and the application of a finite element formulation using solid elements. Further, the comparison of the natural frequencies of a discrete rotor model with a continuous rotor model is documented. To account for uncertainties associated with the structural and loading models, a probabilistic model is derived on the basis of literature review and measurement data from a prototype Multibrid M5000 support structure. The sensitivity study is based on the calculation of a nonlinear coefficient of correlation in conjunction with predetermined designs of experiments. This is conducted by a systematic analysis of the influence of the random variables on limit state responses and hence on the structural reliability. Integrating the analyses and sensitivity studies of the fatigue and serviceability limit state models developed in this paper as well as the ultimate limit state models in Thöns et al. (“Ultimate Limit State Model Basis for Assessment of Offshore Wind Energy Converters,” ASME J. Offshore Mech. Arct. Eng.), the model basis for the assessment is completed. The process of establishing and analyzing such a model basis contributes to a detailed understanding of the deterministic and probabilistic characteristics of the structure and provides valuable insights in regard to the significance of available data.

EXPERIMENTAL EVALUATION OF FLEXURAL CAPACITY OF FULL SCALE PRECAST CONCRETE SHEETPILE

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Geem Eng Tan ◽  
Tai Boon Ong ◽  
Kok Keong Choong ◽  
Chong Yong Ong
Keyword(s):  
Precast Concrete ◽  
Limit State ◽  
Bending Moment ◽  
Test Method ◽  
Ultimate Limit State ◽  
Flexural Capacity ◽  
Test Procedures ◽  
Ground Conditions ◽  
Nursing College ◽  
Set Up

A flexural capacity test is presented of a long precast concrete sheetpile system, intended as a protection wall for a water storage canal bank in soft-ground conditions, for a nursing college in Penang, Malaysia. The precast concrete sheetpile with a length of 7 m and a maximum exposed corrugated-section height of 1.8 m, was designed at Ultimate Limit State (ULS) bending moment of 175 kNm. A total of 2 specimens of precast concrete sheetpiles were tested in the Heavy Structure Laboratory at School of Civil Engineering, Universiti Sains Malaysia. The test method specified in Malaysian Standard MS 1314 was adopted. The results showed that the capacity of Specimens 1 and 2 were respectively 1.49 and 1.48 times higher than the designed capacity at ULS. The test set-up, to reflect the practical behavior of precast concrete sheetpile, and the test procedures are also described.

scholarly journals Safety Concept for Textile-Reinforced Concrete Structures with Bending Load

2020 ◽  
Vol 10 (20) ◽  
pp. 7328
Author(s):  
Sergej Rempel ◽  
Marcus Ricker ◽  
Josef Hegger
Keyword(s):  
Limit State ◽  
Concrete Structures ◽  
Experimental Tests ◽  
Design Model ◽  
Tensile Failure ◽  
Ultimate Limit State ◽  
Textile Reinforced Concrete ◽  
Safety Requirements ◽  
Bending Load ◽  
Effective Depth

In most countries, for the production and execution of concrete structures with textile reinforcement, building owners must have a general approval (e.g., “abZ” in Germany) or an individual license (e.g., “ZiE” in Germany). Therefore, it is quite common for building authorities to request experimental tests that evaluate the ultimate limit state (ULS) and the serviceability limit state (SLS). However, these experimental tests are detailed, time-consuming and expensive. A practical and simple design model would help to reduce the number of tests needed and would offer structural planners a useful tool. An important aspect is that such design model must fulfil a set of reliability requirements in order to guarantee an adequate safety standard. To this end, probabilistic calculations are required. For the setup of such model, different parameters must be considered, namely the effective depth d and the tensile failure stress of the textile ft for the concrete compressive strength fc. This article presents the probabilistic calculations needed to attain a general safety factor γT that satisfies all the safety requirements for the textile reinforcement of concrete structures with bending load.

scholarly journals Interface Shear Strength at Various Joint Types in High-Strength Precast Concrete Structures

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4364
Author(s):  
Young-Jin Kim ◽  
Won-Jong Chin ◽  
Se-Jin Jeon
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Compressive Stress ◽  
Precast Concrete ◽  
Concrete Structures ◽  
High Strength ◽  
Curing Temperature ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Failure Loads

More precast concrete structures have recently been constructed due to their many advantages when compared to conventional cast-in-place construction. Structural behavior at the joints between the precast segments can significantly affect the overall integrity, safety, and serviceability of the structure. In this study, therefore, the interface shear strength of high-strength precast members was investigated by performing push-off tests with the following variables: compressive strength of precast members, dry or wet joint, number and height of shear keys, joint width, filler type, curing temperature, and lateral compressive stress. The test results were analyzed to reveal the effect of each test variable on the joint shear strengths of the specimens. For instance, the failure loads were increased by 14–140%, depending on the lateral compressive stress, as the specified compressive strength of the precast members was increased from 80 to 150 MPa in the dry joints. The failure loads of the wet joints strongly depended on the strength of the filler rather than on that of the precast members and, as a result, the specimen with ultra-high-strength concrete filler was 46–48% stronger than those with high-strength mortar filler. The shear strengths of various joint types obtained from the test were further analyzed in comparison with the predictive equations of Japan Society of Civil Engineers (JSCE) and American Association of State Highway and Transportation Officials (AASHTO) with the aim of validating the appropriateness of these design provisions. In particular, an improved value of a coefficient in the JSCE equation is proposed to cover a range of compressive strengths in various precast members and filling materials.

scholarly journals Performance Improvement of a Fiber-Reinforced Polymer Bar for a Reinforced Sea Sand and Seawater Concrete Beam in the Serviceability Limit State

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 654 ◽  
Author(s):  
Jiafei Jiang ◽  
Jie Luo ◽  
Jiangtao Yu ◽  
Zhichen Wang
Keyword(s):  
Composite Beam ◽  
Limit State ◽  
Concrete Structures ◽  
Fiber Reinforced Polymer ◽  
Serviceability Limit State ◽  
Reinforced Polymer ◽  
Cracking Control ◽  
Sea Sand ◽  
Optic Fibers ◽  
Frp Bars

Fiber-reinforced polymer (FRP) has supreme resistance to corrosion and can be designed with optic fibers. FRP can be an alternative to steel reinforcement for concrete structures, and can serve as a sensor for smart concrete structures. Due to poor cracking control and bond performance, the limit of flexural capacity in the serviceability limit state has not been determined, which has obstructed the wider application of FRP bars in smart structures. In this study, in order to overcome these shortcomings, a new engineering cementitious composite (ECC) with superior tensile strain capacity was used to replace the cover around the FRP bars in the tensile zone. To investigate the anti-cracking performance of the new composite beam, seven simply supported beams were designed. In the preliminary investigation, the longitudinal FRP bars in these beams were designed without optic fibers to focus on the mechanical behavior. The beams were tested under four-point load and measured using the digital sensor technique, digital image correlation (DIC). The test results showed that introducing a new ECC layer on the tensile side improves the cracking control and flexural behavior (load capacity and deformability) of a FRP-reinforced sea sand and seawater concrete (SSC) beam, especially in the serviceability limit state. We demonstrate the new composite beam can steadily and fully improve the tensile capacity of FRP bars, which is the basis of using FRP bars as sensors.

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