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International Concrete Abstracts Portal

Showing 1-5 of 13 Abstracts search results

Document: 

SP323

Date: 

May 14, 2018

Publication:

Symposium Papers

Volume:

323

Abstract:

Load testing of concrete bridges is a practice with a long history. Historically, and particularly before the unification of design and construction practices through codes, load testing was performed to show the travelling public that a newly built bridge was safe for use. Nowadays, with the aging infrastructure and increasing loads in developed countries, load testing is performed mostly for existing structures either as diagnostic or proof tests. For newly built bridges, diagnostic load testing may be required as a verification of design assumptions, particularly for atypical bridge materials, designs, or geometries. For existing bridges, diagnostic load testing may be used to improve analysis assumptions such as composite action between girders and deck, and contribution of parapets and other nonstructural members to stiffness. Proof load testing may be used to demonstrate that a structure can carry a given load when there are doubts with regard to the effect of material degradation, or when sufficient information about the structure is lacking to carry out an analytical assessment.


Document: 

SP-323_07

Date: 

May 1, 2018

Author(s):

Joan Ramon Casas, Piotr Olaszek, Juliusz Ciesla, Krzysztof Germaniuk

Publication:

Symposium Papers

Volume:

323

Abstract:

The paper presents principles of diagnostic load tests of concrete bridges performed in Europe and one example of application from Poland. The common basis of the load testing techniques and methods were developed within the European Research Project ARCHES (Assessment and Rehabilitation of Central European Highway Infrastructure) and the main objectives and results of the project will be presented herein. Based on that, an example of application will follow. The presented example of load tests is an evaluation of newly built reinforced concrete slab bridge. The bridge is a seven-span continuous structure with spans length of 14.05+18.03+15.31+15.63+18.97+18.60+14.34 m [553+710+603+615+747+732+567 in]. After construction, during cleaning the bottom surface of the structure many cracks were noticed in the tension zone. The process of bridge load testing was concentrated on the analysis of the cause of cracks appearing and estimation of the load carrying capacity of the bridge. The investigation range contained the following: tests of material properties, analytical calculations, visual examination of the bottom surface of the structure before, during and after load testing; measurements under test loading: deflection, selected cracks width and supports displacement. The final conclusions included the causes of crack appearing and recommendations for the future bridge service.


Document: 

SP-323_11

Date: 

May 1, 2018

Author(s):

E.S. Hernandez and J.J. Myers

Publication:

Symposium Papers

Volume:

323

Abstract:

Self-consolidating concrete (SCC) has emerged as an alternative to build stronger structures with longer service life. Despite the advantages of using SCC, there are some concerns related to its service performance. The effect of a smaller coarse aggregate size and larger paste content is of special interest. It is fundamental to monitor the response to service loads of infrastructure employing SCC in prestressed concrete members. Bridge A7957 was built employing normal-strength and high-strength self-consolidating concrete in its main supporting members. The diagnostic test protocol implemented in this research included static and dynamic tests and the calibration of refined finite element models simulating the static loads acting on the structure during the first series of diagnostic tests. The main objective of this study centered on (a) presenting a diagnostic test protocol using robust and reliable measurement devices (including noncontact laser technology) to record the bridge’s initial service response; and (b) obtaining the initial spans’ performance to evaluate and compare the SCC versus conventional concrete girders’ response when subjected to service loads. The initial response of the end spans (similar geometry and target compressive strength, but with girders fabricated using concrete of different rheology) was compared, and no significant difference was observed.


Document: 

SP-323_02

Date: 

May 1, 2018

Author(s):

Mauricio Diaz Arancibia and Pinar Okumus

Publication:

Symposium Papers

Volume:

323

Abstract:

Recurrent service problems and uncertainties in load distribution have been frequently reported by Departments of Transportation for skewed bridges. Service problems, such as deck cracking or excessive bridge racking can lead to bridge deterioration, and indicate the need of a better understanding of the structural response of high skew bridges to service loading. This paper presents the instrumentation and load testing of a three-span, medium span length, prestressed concrete bridge with 64° of skew to understand service, analysis and design problems associated with skew. The instrumentation plan for the bridge was developed based on service problems observed in concrete bridges with high skew such as deck cracking and displacements, as reported by the literature and by regular bridge inspections. Complete understanding of skew related responses required both short-term testing and long-term load monitoring. Structural responses of the key areas of the bridge to live and temperature loads and shrinkage were measured. The effects of certain bridge details on live load distribution were determined using finite element models validated through short-term load testing data. The evolution and magnitude of bearing movements and deck strains were captured for long periods of opposite thermal tendencies.


Document: 

SP-323_04

Date: 

May 1, 2018

Author(s):

Brett Commander and Jesse Sipple

Publication:

Symposium Papers

Volume:

323

Abstract:

Load testing and structural monitoring facilitated the passage of several super-heavy permit loads at the Burns Harbor access bridge near Portage, IN. Twenty super-heavy permit loads, with gross vehicle weights reaching 848 kips (3770 kN), were required to cross the bridge, which was the only feasible route out of the port. Preliminary load ratings were acceptable due to three factors; the specialized transport’s large footprint effectively distributed load, the bridge was designed for Michigan Truck Trains, and the bridge was assumed to be in good condition. The last condition came into question due to significant cracks throughout the prestressed concrete girders caused by delayed ettringite formation (DEF). While DEF cracks were a function of improper curing and not related to live-load effects, the Indiana Department of Transportation (INDOT) was concerned that repeated heavy loads would negatively influence cracks and the bridge’s overall long-term performance. Due to the cargo’s importance to the local community and lack of an alternate route, INDOT allowed use of the bridge after load tests proved that the transports would not cause damage or reduce the bridge’s service life. Structural monitoring performed during the entire transport period verified structural performance was not diminished during the numerous crossings.


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