Extended experimental and numerical investigations on constraint forces from imposed deformations

Self Cite

This paper presents the results of evaluations on the redistribution of internal forces from the span to the support area using nonlinear finite element calculations. The motivation is the internalization of bridges, particularly the reconstruction of single-span beams arranged in a row to a continuous beam system. When integralizing a bridge, it can be assumed that the existing bridge is designed according to standards, which are no longer valid. If the integralized bridge is loaded and designed according to the new standard, the problem may be that the existing structure has insufficient reinforcement. For singlespan bridges, the flexural reinforcement in the span may be considered critical.The degree of reinforcement in the support area can then be adjusted individually, which offers the possibility of transferring internal forces from the span to the support area if they cannot be fully absorbed by the existing reinforcement.

“…After the reinforcement started to yield, a residual amount of the redistribution of the internal forces could still be detected. The same finding was made in other studies 39,40 …”

Section: Nonlinear Numerical Evaluationssupporting

confidence: 90%

“…The same finding was made in other studies. 39,40 Figure 13 shows the tensile damage variable d t of the concrete, which represents the cracked areas of the concrete. Figure 14 shows the plastic strain of the reinforcing steel; it can be observed that the reinforcement in the span and in the support area started yielding.…”

Section: Moment Redistributionmentioning

confidence: 99%

Redistribution of internal forces from the span to the support

Berger

2022

Self Cite

“…The parameters for the effective creep ratio are the second moment of area and the material properties, where deviations can be seen. According to Berger et al, 22 it was experimentally found that the stiffness at low load levels is underestimated by analytical calculations. Furthermore, it has already been determined for the post‐tensioned test body, see Section 7.2.1, that the theoretical material properties do not correspond exactly to the experimental values.…”

Section: Test Resultsmentioning

confidence: 99%

Long‐term investigations on reduction of constraint forces caused by imposed deformation by creep

Berger

Feix

2020

Self Cite

External constraint is an action that arises when a structure cannot deform freely. This deformation may be caused by imposed deformation. These deformations lead to support reactions and internal forces only in statically indeterminate systems and are proportional to the absolute values of the structural stiffness. The structural stiffness is significantly reduced by creep of concrete. The classical models for calculating the creep impact on constraint forces assume linear‐elastic or linear‐viscoelastic behavior. The influence of the reinforcement on the creep deformation is neglected as well as the effect of cracking. For this reason, experiments were carried out to obtain results on the creep‐induced degradation of constrained forces caused by imposed deformations. Long‐term experiments were performed on a two‐span beam on which the constraint force was applied by lifting the middle support. Dimensions of the test bodies were l/w/h = 7.3 m/0.4 m/0.2 m. Measurements were carried out on two test bodies, one conventional reinforced test body and one post‐tensioned test body. Thus, the stiffness of a cracked and non‐cracked test body was given. As a result, the influence of the reinforcement as well as effect of crack formation can be taken into account. The experiment lasted over a period of 500 days. The aim is to compare the results of the theoretical models taking into account different stiffness and different creep behavior with the measured test results.

“…V h , V w , and V l represent the depth, width, and length of the void respectively F I G U R E 3 The three-dimensional finite element model and the mesh generation distance of the pipe was refined. The three-dimensional eight-node reduced integral solid element (C3D8R) with hourglass control was used in the model, [14][15][16][17] and the reasonable sizes of the FEM and meshes were determined using sensitivity analysis. At a model width of 10 times the diameter of the pipe, the maximum and minimum mesh size was equal to 0.15 and 0.08 m respectively, so the boundary effect and the impact of the mesh size on the model results could be ignored.…”

Section: Model Descriptionmentioning

confidence: 99%

Prediction model for maximum shear displacement of pipe joints with preexisting defects based on finite element–multiple nonlinear regression method

Fang

Zhang

et al. 2021

Under the coupling effect of the defects inside and around pipes, the shear displacement of the joints of old concrete pipes fallen into disrepair usually shows an accelerated deterioration trend, and its excessive value can lead to structural damage or fluid leakage. Therefore, developing a prediction model for the maximum shear displacement of concrete drainage pipe joints with preexisting defects is of crucial significance. To this end, this work selects internal corrosion and erosion voids as the typical defects inside and around old pipes, establishes 300 sets of three‐dimensional fine finite element (FE) models of the concrete drainage pipes with corrosion and void, and verifies the reliability of the developed FE model by the full‐scale tests. Based on the verified FE data, a prediction model is successfully proposed for the assessment of the maximum shear displacement of the concrete drainage pipe joints with corrosion and void defects. Moreover, parameter sensitivity analysis is carried out to reveal their relative contribution to the maximum shear displacement of pipe joints. The results show that the model proposed herein has the ability to accurately predict the maximum shear displacement of the pipe joints. The maximum and minimum relative error between the value predicted by the proposed model and the one computed by the FE model is also 12.4% and 4.8% respectively. Moreover, the traffic load with a contribution of 28.7% has the greatest impact on the maximum shear displacement of pipe joints.