Dowel

This paper deals with the load-carrying capacity calculation of laterally loaded metal dowel type connections according to Eurocode 5. It is based on analytically derived, relatively complicated mathematical relationships, and thus it can be quite laborious for practical use. The aim is to propose a possible simplification of the calculation. Due to quite a great variability of fasteners’ types and the connection arrangements, the attention is paid to the most commonly used nailed connections. There was performed quite an extensive parametric study focused on the calculation of load-carrying capacity of the simple shear and double shear plane nail connections, joining two or three timber parts of softwood or hardwood. Based on the study results, in conclusion there are presented simplifying recommendations for practical design.

This paper presents a mechanical model of the shear resistance based on Critical Shear Crack Theory (CSCT) and its application for the checking of the shear ultimate state of self-stressed elements reinforced with FRP bars. The shear force, which is transmitted through the inclined crack by aggregate interlock, residual tensile strength, dowel action and inclined chord of the compression concrete, is calculated depending on the value of the inclined crack opening, determined according to the modified law “bond-slip” for FRP bars. The reliability of the proposed approach is confirmed by comparison both with the results of our own experimental investigations and with numerous research results by various authors.

Flat-slab building structures possesses major advantages over traditional slab-beam-column structures because of the free design of space, shorter construction time, architectural –functional and economical aspects. Because of the absence of deep beams and shear walls, flat-slab structural system is significantly more flexible for lateral loads then traditional RC frame system and that make the system more vulnerable under seismic events. The results from the analysis for few types of construction systems which is presented in the paper show that flat slab system with certain modifications (design of beam in the perimeter of the building and/or RC walls) can achieve rational factor of behaviour considering EC8 and can be consider as a system with acceptable seismic risk. Modifications with additional construction elements improve small bearing capacity of the system and increase strength and stiffness, improving seismic behaviour of flat-slab construction system. Selected result fro...

Highway agencies continuously strive to expedite pavement construction and repairs and to evaluate materials and methods to provide long-lasting pavements. As part of this effort, agencies have used precast concrete slabs for more than 10 years with successive improvements in processes and systems. The Virginia Department of Transportation recently used two precast systems along with conventional cast-in-place repairs on a section of jointed reinforced concrete pavement on I-66 near Washington, D.C. One precast system, precast concrete pavement (PCP), used doweled joints. The other precast system, prestressed precast concrete pavement (PPCP), used transversely prestressed slabs post-tensioned in the longitudinal direction. Both precast systems are performing satisfactorily after 1.5 years of traffic, and the contractor was satisfied with the constructability. In multiple locations, transverse expansion joints in PPCP were observed to be wider than the ½-in. width specified; excessiv...

Non-corrosive fiber-reinforced polymers (FRP) are becoming a desirable replacement to steel bars in reinforcing/prestressing concrete structures. However, the difference between the two materials is not only related to the properties in the longitudinal direction of the bars as most of the current research work and design guidelines are concerned with. The properties in the transverse direction of the bars have basic differences, which may influence the beam strength and its mode of failure. This paper presents a comprehensive analytical modeling for evaluating the strength of concrete beams reinforced and (or) prestressed with FRP bars and the corresponding mode of failure. It takes into account significant parameters such as the crack path geometry, the crack width, and the properties of the bars in both longitudinal and transverse directions. The proposed analysis identifies any premature failure of beam due to the dowel failure of FRP reinforcement and determines the contributio...

GPR (Ground Penetrating Radar) is non-destructive equipment coming to be accepted in diagnostics of road structures. The paper describes state-of-the-art of a GPR usage in several European countries in this field. Beside basic GPR applications in the field of road diagnostics like a determination of pavement layer depths and a location of joint dowel bars in concrete pavements the more complicated application possibilities are mentioned such as detection of voids under the concrete slabs of rigid pavements, detection of excessive amount of water in structural layers of pavements, determination of crack depth in the bituminous layers etc. The situation in the Czech Republic is described in the paper and some projects concerning GPR testing, the author participated on, are mentioned.

A finite element model for nonlinear analysis of jointed concrete pavements is presented. The model allows for nonlinear representation of the properties of concrete, both in compression and in tension. It also accounts for the behavior under cyclic loading considering the nonlinear fatigue damage accumulation in concrete. An improved model accounting for the relative deformation between the dowel bars and the concrete slabs is presented to analyze pavement slabs connected with dowels. The sub-grade model is capable of representing pumping of the fine material with repetitive loading. Limited validation of the model is presented using data available in the literature.

Indonesia is a country with a rich maritime history. The finding of ancient wooden ark in Punjulharjo site, Rembang, Central Java that was ascribed to seventh century A.D., was a proof of the growth of the ancient maritime culture. This finding needs some support to find out the origin of the ark. This research was intended to identify the wood species used on board, stringer and dowel part. The identification result was expected to be useful to estimate the origin of the wooden ark.The wood identification process was done by observing the wood anatomy on the board, stringer and the dowel part using loupe and light microscopy. The identification result showed that according to its wood’s characteristic, the board part of the ark was predicted as wood from the family Sapotaceae, genus Palaquium, and species Palaquium spp. (Nyatoh Wood); wood used as stringer part was estimated as wood from the family of Olacaceae, family Scorodocarpus and species Scorodocarpus bornesis (Kulim Wood) a...

Abstract: Traffic in lanes adjacent to a deck that is being widened or reconstructed causes deflections and vibrations in the fresh concrete deck. A study of the effects of these disturbances in concrete decks is reported here. Decks in service for years were inspected ...

A finite element model for nonlinear analysis of jointed concrete pavements is presented. The model allows for nonlinear representation of the properties of concrete, both in compression and in tension. It also accounts for the behavior under cyclic loading considering the nonlinear fatigue damage accumulation in concrete. An improved model accounting for the relative deformation between the dowel bars and the concrete slabs is presented to analyze pavement slabs connected with dowels. The sub-grade model is capable of representing pumping of the fine material with repetitive loading. Limited validation of the model is presented using data available in the literature.

This article presents an experimental study aiming to provide reliable experimental data for the prediction of the shear strength of reinforced concrete beams without stirrups. The shear strength results obtained from the proposed model as well as those from the design codes (ACI 318, Eurocode 2 and BS 8110) are compared with the database containing 700 beams made of both high strength concrete and normal strength concrete. Furthermore, the experimental results were used to assess the contribution of each shear mechanism obtained from Chen’s, Cavagnis’s and Fernández Ruiz’s models. The contribution of these various shear-transfer actions is also quantified experimentally, using a digital image correlation. As a result, the measured contributions of dowel action, aggregate interlock and compression zone to the total shear resistance were estimated as 45% to 50%, 20% to 35% and 17% to 31%, respectively, for high strength concrete beams. On the contrary, the average test-to-predicted c...

Reinforced concrete structures are relatively complex to analyze, with nonlinear effects like cracking, crushing, steel yielding, aggregate interlock, dowel effect, concrete-rebar interaction and so on. The concrete damaged plasticity CDP model is a consolidated smeared-crack model which accounts for multiaxial behavior with good agreement to experimental results. One particular relevant application which benefits greatly from such feature is the shear wall, as shear stress significantly influences its overall behavior, therefore multiaxial constitutive models and three-dimensional finite elements usage consist in a fitting modeling approach. Reinforced concrete shear walls are structures especially useful for lateral force-resisting systems, as they provide ductility, stiffness and strength. Albeit CDP is widely applied, its parameters are not consensus in the literature, which represents a relevant research gap. The present work considers and compares CDP parameters from relevant ...

Concrete joint failure is a major distress mode in rigid pavements. Improving the joint performance in concrete pavements could yield substantial savings in terms of reduced maintenance and rehabilitation costs. The newly developed Hinged Dowel System (HDS) is a means for transferring loads across the concrete pavement joints. The HDS was patented as a new invention by the United States Patent and Trademark Office, and it is envisioned that it could significantly reduce the potential for joint failure in concrete pavements. The HDS assembly comprises a number of dowel bars and a collective hinge provided at the mid-length of the dowel bars. A finite element analysis showed that the application of HDS reduces the shear stress in concrete pavement joints by approximately 15% when compared to the conventional dowel bars. This amount of reduction in shear stress could translate into a significant reduction in shear-induced failures in concrete pavements. The HDS includes mechanisms whic...