The research project „Monitoring Based Analyses of a Integral Bridge“ aims at the monitoring based investigation of design principles and load models associated with integral bridge structures. In particular, the processes creep and shrinkage, temperature loads, traffic loads and the soil-structure interaction are analyzed. A proof loading procedure performed in 2010 provides the inputs for the inverse identification of the structures characteristics and boundary conditions. The integral bridge „Marktwasserbrücke“, located on the S-33, was instrumented with an integrative, permanent monitoring system during its construction in December 2008. 12 fiber optic strain and 8 fiber optic temperature sensors have been installed in the concrete deck slab parallel to the lower and top reinforcement layer during casting. Furthermore 2 extensometers as well as fiber optic and electrical strain gages have been placed in the reinforced earth dam above the inclined approach slab. The monitoring data collected during the last two years leads to the following conclusions: (1) The maximum strains recorded in the concrete deck during the proof loading procedure with three 40-to trucks amounts to ~ 0.015 ‰, which is significantly below the threshold of cracking (0.092 ‰). (2) With regard to the stress related serviceability limit state a safety of 1.13 is given for condition I and 1.33 for condition II. (3) Based on an intensive 14 day traffic monitoring campaign and by extrapolation to 100 years the LM1- load factors are found to be ?= 0.75 for condition I and ?= 0.50 for condition II assuming soft foundation. For a stiff foundation the respective factors are ?= 1.21 and ?= 0.73. (4) The extreme mechanical strains within the concrete deck due to dead and traffic loads were identified to be between -0.15 ‰ and 0.60 ‰. They by far exceed the thermal contributions of roughly ±0.04 ‰. (5) Abutment movement and average temperature in the deck are highly correlated. The observed displacements lie approximately 40 % below the expectations based on the equation of free thermal expansion. (6) With a probability of p> 23 % earth pressure is acting against the abutment wall. The active earth pressure is activated with a probability of 1.7 %. (7) The strain field interpolated from 30 strain sensors indicates a qualitative agreement between design assumptions and reality. The observed strains are highly correlated to the abutment movement as well as the average temperature of the concrete deck. However, strain redistribution was encountered for the time of maximum expansion and maximum contraction. (Author/publisher)
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