PARAPET STIFFNESS EFFECT ON LOAD CARRYING CAPACITY OF MULTI-LANE CONCRETE SLAB BRIDGES

Author(s):  
Sarah Jaber ◽  
Mounir Mabsout ◽  
Kassim Tarhini

Bridge specifications do not consider the effect of parapet stiffness in the analysis and design of reinforced concrete slab bridges. This paper performs a parametric investigation using finite element analysis (FEA) to study the effects of parapet stiffness on live load-carrying capacity of two-span, three-and four-lane concrete slab bridges. This study analyzed 96 highway bridge cases with varied parameters such as span-length, bridge width, and parapet stiffness within practical ranges. Reinforced concrete parapets or railings, built integrally with the bridge deck, were placed on one and/or both sides of bridge deck. The longitudinal bending moments calculated using the FEA results were compared with reference bridge cases without parapets, as well as AASHTO Standard and LRFD specifications. The FEA results presented in this paper showed that the presence of concrete parapets reduces the negative bending moments by 15% to 60% and the positive bending moments by 10% to 45%. The reduction in longitudinal bending moments can mean an increase in the load-carrying capacity of such bridges depending on the parapet stiffness. This investigation can assist engineers in modeling the actual bridge geometry more accurately for estimating the load-carrying capacity of existing concrete bridges. Hence, new bridges can be designed by considering the presence of concrete parapets. Parapets can be used as an alternative for strengthening existing one and two-span reinforced concrete slab bridges.

2015 ◽  
Vol 769 ◽  
pp. 97-100
Author(s):  
Oldrich Sucharda ◽  
Jan Kubosek

The paper deals with the designing and analysing of concrete structures. A particular attention is paid to a multi-segment slab made from reinforced concrete. The purpose of the paper is to evaluate, in a non-linear analysis, impacts of input parameters of the concrete on the real load-carrying capacity of the ceiling which has been designed originally in DeMKP. FEM software applications have been used in the analysis. This is an in-house application DeMKP for designing the systems in line with standardised procedures. Another software is ATENA Science which can be used for non-linear analyses.


2014 ◽  
Vol 897 ◽  
pp. 157-160
Author(s):  
Peter Kotes

FRP (Fiber Reinforced Plastic) materials are corrosion resistant not requiring any specific treatment. The utilization of these materials is expanding. New research works have started to focus on using these materials on self-contained formwork in composite systems. It allows decreasing the concrete cover on minimum value just to assure sufficient bonding between reinforcement and concrete (the influence of aggressive environment is minimal). Moreover, the stay-in-place formwork is self-contained. It means using this system as formwork during casting of concrete and another supporting structure is not needed. The paper is focused on experimental analysis of stay-in-place GFRP (Fiberglass Reinforced Plastic) formwork in composite system (three-functional GFRP formwork and reinforced concrete slab – RC slab) and its use on floors in building structures. The load-carrying capacity of the composite system is highly influenced by quality of cohesion between GFRP formwork and concrete. This cohesion was investigated by using “push tests”. The results from experimental push tests were compared with the numerical model and also will serve for numerical modelling of real bonding of the girders.


Author(s):  
Sarah Jaber ◽  
Mounir Mabsout ◽  
Kassim Tarhini

The American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications or LRFD do not account for the presence of railings in the analysis and design of concrete slab bridges. This paper presents a parametric investigation of the influence of railing stiffness on the wheel load distribution in simply-supported, two-equal-span, and one-and two-lane reinforced concrete slab bridges using the finite-element analysis (FEA). A total of 160 bridge cases were modeled and bridge parameters such as span lengths and slab widths were varied within practical ranges. Various railing stiffness were investigated by assuming railings built integrally with the bridge deck and placed on both edges of the bridge. The FEA wheel load distribution and longitudinal bending moments were compared with reference bridge slabs without railings as well as to the AASHTO design procedures. Accordingly, the presence of railings reduced the FEA negative moments by a range of 54% to 72% and the FEA positive moments by a range of 40% to 61% depending on the railing stiffness. This reduction in slab moments due to the presence of railings could be considered an increase in the bridges load carrying capacity. The results of this investigation will assist bridge engineers in better designing and/or evaluating concrete slab bridges in the presence of railings. This could also be considered an alternative for strengthening existing concrete slab bridges.


Author(s):  
Paolo Foraboschi

Renovation, restoration, remodeling, refurbishment, and retrofitting of build-ings often imply modifying the behavior of the structural system. Modification sometimes includes applying forces (i.e., concentrated loads) to beams that before were subjected to distributed loads only. For a reinforced concrete structure, the new condition causes a beam to bear a concentrated load with the crack pattern that was produced by the distributed loads that acted in the past. If the concentrated load is applied at or near the beam’s midspan, the new shear demand reaches the maximum around the midspan. But around the midspan, the cracks are vertical or quasi-vertical, and no inclined bar is present. So, the actual shear capacity around the midspan not only is low, but also can be substantially lower than the new demand. In order to bring the beam capacity up to the demand, fiber-reinforced-polymer composites can be used. This paper presents a design method to increase the concentrated load-carrying capacity of reinforced concrete beams whose load distribution has to be changed from distributed to concentrated, and an analytical model to pre-dict the concentrated load-carrying capacity of a beam in the strengthened state.


2015 ◽  
Vol 2 (1) ◽  
Author(s):  
N. Aravind ◽  
Amiya K. Samanta ◽  
Dilip Kr. Singha Roy ◽  
Joseph V. Thanikal

AbstractStrengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.


2021 ◽  
Author(s):  
Anil K. Kar

Reinforced concrete is the number one medium of construction. It is important to have good quality concrete and reinforcing bar (rebar). It is equally important to have competent bond between rebar and concrete. About six decades ago ribbed rebars of high strength steel started replacing plain round bars of mild steel, the use of which had made reinforced concrete constructions durable. It was overlooked that ribbed rebars of carbon steel would be highly susceptible to corrosion at accelerated rates. That would not only make reinforced concrete constructions reach states of distress early, that could also destroy or reduce bond between ribbed rebars and concrete. The continued use of ribbed rebars of high strength carbon steel demonstrates a widespread lack of understanding of the phenomenon of bond between rebars and concrete. This lack of understanding of bond has led to the introduction of epoxy coated ribbed rebars, ribbed stainless steel bars and glass fiber reinforced and granite reinforced polymer rebars, all of which permit reinforced concrete carry static loads because of engagement between such rebars and concrete. But the load-carrying capacity of reinforced concrete elements is impaired, and such elements become vulnerable to local or even total failure during vibratory loads. The use of PSWC-BAR, characterized by its plain surface and wave-type configuration, permits the use of medium strength and high strength steel. In the absence of ribs, the rate of corrosion is greatly reduced. The use of PSWC-BARs, at no added effort or cost, in lieu of conventional ribbed bars, leads to enhancement of effective bond or engagement between such rebars and concrete, thereby leading to increased load-carrying capacity, several-fold higher life span, ductility and energy-absorbing capacity, and great reduction in life cycle cost and adverse impact of construction on the environment and the global climate. In keeping with a lack of understanding of bond between rebars and concrete, there is arbitrariness in the selection of the required level of percent elongation and ductility of rebars.


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