Measuring amplitude and phase of continuous ultrasonic waves with a lock-in amplifier is shown to give similarly sensitive indicators of concrete damage as pulsed coda wave analysis, but maintains its sensitivity at considerably much lower signal levels. Continuous and pulsed measurements were performed on a concrete slab subjected to cyclically increased damage level. In the unloaded phase eac...

Concrete infrastructure systems require large capital investments and resource flows to construct and maintain. An integrated life cycle assessment and cost model was developed to evaluate infrastructure sustainability, and compare alternative materials and designs using environmental, economic and social indicators. The model is applied to two alternative concrete bridge deck designs: one a co...

Experiments were conducted to measure the transportability of radon gas through common concrete samples which were characterized by their mix proportions, dimensions, porosity, air permeability and radon gas diffusion coefficient. Several innovative test systems and methods were designed, fabricated and calibrated to accurately measure these radon gas transport characteristics for concrete and ...

This study concerns improvement of flexural stiffness/strength of concrete members reinforced with externally bonded, aluminum-glass fiber composite (AGC) beams. An experimental program, consisting of seven reinforced concrete slabs and seven reinforced concrete beams strengthened in flexure with AGC beams, was initiated under four-point bending in order to evaluate three parameters: the cross-...

This paper presents a mixed finite element model for the nonlinear time-dependant analysis of composite beams with partial shear connection. The key idea is to consider, as a first approach, a viscoelastic/plastic model for the concrete slab in order to simulate the interaction between the time effects of concrete, such as creep and shrinkage, and the concrete cracking. Creep is taken into acco...

The real temperature distribution within 24 h of the main beam in a single-tower hybrid cable-stayed bridge is analysed according to its actual section and material parameters, as well other factors local atmospheric temperature, geographical environment, solar intensity. results show that internal steel–concrete composite uneven, steel higher than at surface concrete slab. Then, finite element...