Park performed finite element analysis to improve the joint geometry by mitigating the stress and strain concentrations under thermal and traffic loads [13,17]。 Parametric simulations were car- ried out by taking into account the interface shape between pave- ment and joint, gap plate width and thickness, gap plate edge detail。 An improved joint design as indicated in Fig。 2 was proposed by application of round edge of gap plate, trapezoidal interface be- tween pavement and joint as well as intentionally debonded gap plate。 A gap plate with round edge can be used to reduce the stress concentration, while the intentionally debonded plate can increase the distribution of the deformation demand over the  joint。

The joint thickness has a great influence on joint damage。 Thin joint tends to fail directly over the gap plate while thick joint fails at the blockout interface, or further away from the edge of the gap

112 L。 Mo et al。 / Construction and Building Materials 45 (2013)  106–114

Table 5

Simulation results and improved joint   geometry。

Geometrical design Findings and improvements

High stress concentration at the top of the plug/pavement interface: premature cracking, debonding and ultimately failure

Greater distribution of stresses through the whole joint, lower stresses at the plug/pavement interface under joint movement, susceptible to high stresses  under wheel    loading

wider distribution of stresses through the whole joint, significantly lower stresses under wheel  loading

2。 Plug-pavement interface

Trapezoidal/sinusoidal joint is helpful to reduce the stresses levels and improve the stress distribution through the whole joint。 Trapezoidal joint is more practical for easy  installation

2。1 The interface was experiencing stress reversal under traffic loading; The interface stress decreased by reducing the joint angle from 90° to 45°; Significantly reduce the stress level at the top of the plug-interface (Point a); no effective to reduce stress concentration at the edge of gap plate (Point    b)

2。2 Round shape 2。2 Slightly reduce the stress level at Point a; no effect on stress at Point b

3。 Gap plate

3。1 Plate edge

3。1。1  Rectangular edge

Trapezoidal shape had the best performance; the optimum inclination angle ranged from 45° to 90°

3。1。1 Stress and strain concentrations occur at Point    b

3。1。2 Trapezoidal edge 3。1。2 No positive to reduce stress at Point    b

3。1。3 Rounded edge 3。1。3 Reduce the stress levels at Point    b

3。1。4 Conbinder edge 3。1。4 Reduce the stress levels at Point    b

Rounded edged had the best performance; rounding off the top edge of gap plate for practical use

3。2 Plate width 3。2 Reducing gap plate width reduced the risk of cracking at Point  b论文网

3。3 Plate thickness 3。3 2-mm thick gap plate could support an 80-kN axle load; minimum thickness was 4 mm or 6 mm

3。4