Methodology for Proof Load Testing

This chapter deals with the methodology for proof load testing. All aspects of proof load testing that are shared with other load testing methods have been discussed in Part II of Volume 12. In this chapter, the particularities of proof load testing are discussed. These elements include the determination of the target proof load, the procedures followed during a proof load test (loading method, instrumentation, and stop criteria), and the post-processing of proof load test data, including the assessment of a bridge after a proof load test

¿Cómo evaluar la capacidad de puentes de hormigón existentes?

Después de la expansión de la red vial del país, la comunidad de ingenieros civiles y el gobierno tienen un número mayor de puentes existentes a manejar. En el futuro, esos puentes necesitaran mantenimiento y adopciones a los cambios en términos de las cargas vivas. En ese artículo vamos a ver como en Europa y América del Norte se está evaluando la capacidad de puentes de hormigón existentes. Típicamente, la evaluación es primero analítico, y después, dependiendo de la necesidad, experimental. En caso de concluir que no hay capacidad suficiente, diseñamos un refuerzo estructural para el puente. Revisaremos diferentes métodos de cálculo, inspección, pruebas de carga, y reforzamiento para puentes de hormigón existentes

Fatigue of concrete under compression: Database and proposal for high strength concrete

The compressive strength of concrete decreases as an element is subjected to cycles of loading. In a typical fatigue test for the concrete compressive strength, a concrete specimen (typically a cylinder) is loaded between a lower and upper stress limit. These limits are expressed as a fraction of the concrete compressive strength, and can be written as Sminfck and Smaxfck. The value of Smin and Smax are thus between 0 and 1. The upper limit for Smax in experiments is typically 0,95 and Smin can be as low as 0,02. Experiments in which alternating tensile and compressive stresses are applied can also be executed, but this loading case is not considered in the current study. The result of fatigue tests on concrete cylinders in compression is the so-called Wöhler-curve, or S-N curve. In this graph, a (linear) relation is found between the logarithm of the number of cycles N and the maximum fraction of the static compressive strength Smax. In the codes, different expressions are given for the relation between N and Smax. The codes that are studied in this report are the Dutch Code NEN 6723:2009 (Code Committee 351 001 "Technical Foundations for Structures", 2009), the Eurocode suite for concrete: NEN-EN 1992-1-1+C2:2011 (CEN, 2011a) with the Dutch National Annex NEN-EN 1992-1-1+C2:2011/NB:2011 (Code Committee 351 001, 2011a) and NEN-EN 1992-2+C1:2011 (CEN, 2011b) and the Dutch National Annex NEN-EN 1992- 2+C1:2011/NB:2011 (Code Committee 351 001, 2011b), the new Model Code 2010 (fib, 2012). Some expressions from the literature are considered as well, such as the proposal by Hans Bongers (Snijders, 2013) and an expression suitable for higher strengths concrete (Kim and Kim, 1996). The expression for concrete under compression subjected to cycles of loading from NEN-EN 1992-1-1+C2:2011 is more conservative than previously used expressions in the Netherlands. Therefore, different expressions are given in the National Annex NEN-EN 1992-1-1+C2:2011/NB:2011. The S-N relationship given in the Dutch National Annex consists of two equations: the first branch is valid for N ? 106 cycles and the second branch for N > 106 cycles. The transition between these two expressions is not smooth, but instead causes a jump in the Wöhler-curve. Because of this anomaly in the current code provisions, it is necessary to propose a new expression for concrete under cycles of compressive loading. Moreover, the proposed expression should be valid, yet not overly conservative, for high strength concrete. The current Eurocode NEN-EN 1992-1-1+C2:2011 is limited to concrete class C90/105. The fib Model Code goes up to C120. The goal of this report is to develop an expression that is valid up to C120. To check the quality of the proposed expression, it should be compared to experimental results. For this purpose, a database of experiments on (ultra) high strength concrete tested in compressive fatigue is developed first, and then used to validate the new proposal for concrete under cycles of compression.Structural EngineeringCivil Engineering and Geoscience

¿Cómo evaluar la capacidad de puentes de hormigón existentes?

Después de la expansión de la red vial del país, la comunidad de ingenieros civiles y el gobierno tienen un número mayor de puentes existentes a manejar. En el futuro, esos puentes necesitaran mantenimiento y adopciones a los cambios en términos de las cargas vivas. En ese artículo vamos a ver como en Europa y América del Norte se está evaluando la capacidad de puentes de hormigón existentes. Típicamente, la evaluación es primero analítico, y después, dependiendo de la necesidad, experimental. En caso de concluir que no hay capacidad suficiente, diseñamos un refuerzo estructural para el puente. Revisaremos diferentes métodos de cálculo, inspección, pruebas de carga, y reforzamiento para puentes de hormigón existentes.Accepted Author ManuscriptConcrete Structure

Current Codes and Guidelines

This chapter reviews the existing codes and guidelines for load testing of structures. A summary of the main requirements of each existing code is provided, with a focus on the determination of the required load and measurements. The requirements for load testing of bridges and buildings are revised, for new and existing structures. An international perspective is given, revising the practice from Germany, the United Kingdom, Ireland, the United States, France, Switzerland, the Czech Republic, Slovakia, Spain, Italy, Switzerland, Poland, and Hungary. The chapter concludes with a short overview of the current developments and with a discussion of the different available codes and guidelines

Preparation of Load Tests

This chapter discusses the aspects related to the preparation of load tests, regardless of the chosen type of load test. After determination of the test objectives, the first step should be a technical inspection of the bridge and bridge site. With this information, the preparatory calculations (assessment for existing bridges and expected behavior during the test) can be carried out. Once the analytical results are available, the practical aspects of testing can be prepared: planning, required personnel, method for applying the load, considerations regarding traffic control and safety, and the development of the sensor and data acquisition plan. It is good practice to summarize all preparatory aspects in a preparation report and provide this information to the client/owner and all parties involved with the load test

General Considerations for the Execution of Load Tests

This chapter discusses the aspects related to the execution of load tests regardless of the chosen type of load test. The main elements required for the execution of the load test are the equipment for applying the load and the equipment for measuring and displaying (if required) the structural responses. This chapter reviews the commonly used equipment for applying the loading and discusses all aspects related to the measurements. The next topic is the practical aspects related to the execution. This topic deals with communication on site during the load test and important safety aspects during a load test