This suggests that the steel content may determine the minimum required anchorage length for full capacity development.Based on the predicted variations of strength (as well as the stiffness) of PRC beams as either well as the intensity of bearing stresses of shear studs at the anchorage regions, an empirical parabolic La/l�Cl/h relationship (4) as shown in Figure 10 is recommended for preliminarily determining the minimum anchorage length required. The equation should be good enough for normal combinations of plate thicknesses and steel ratios when the material strengths are similar to the for??1.0��lh��4.0.(4)Figure?ones used in this study:Lal=0.03(lh)2?0.27(lh)+1 10Recommended minimum La/l value for preliminary design.It is noted that when the span-depth ratios l/h equal to 1, 2, and 4, the corresponding Lo/l ratios are 0.

76, 0.58, and 0.4, respectively. By adopting these Lo/l ratios, it can be found from Table 2 that most of the computed shear strengths Vmax ,comp are higher than the corresponding theoretical design shear strength Vu*, except the ones with short span (SPrc units) combined with thick steel plates. The reasons for causing insufficient strength of PRC coupling beams will be discussed in the next section.3.4. Effects of Wall Reinforcement RatioIt has been shown in Table 2 that all the SPrc units with thick steel plates of tp = 36mm could not develop their full capacities (Vmax ,comp/Vu* < 1), and the problem was likely caused by insufficient wall reinforcement. In order to investigate how much wall reinforcement would be required for Unit SPrc-1.

0c3, the wall reinforcement ratios were varied in this model, and the computed load-drift responses are presented in Figure 11. This model with a plate anchorage length of 1.0l was chosen for the investigation as it was unlikely that its premature failure was associated with insufficient anchorage length. For simplification, the wall piers were provided with the same percentage of reinforcement in the vertical and the horizontal directions, that is, ��wx = ��wy. In real practice, due to high axial loads acting on wall piers, steel ratio in walls in the vertical direction (��wy) is often higher than that in the horizontal direction (��wx).Figure 11Computed load-drift responses of Unit SPrc-1.0c3 with different wall reinforcement ratios.

The increase in beam strength with the increase in the wall reinforcement ratio confirms that the premature failures of the SPrc units with thick plates were caused by insufficient wall reinforcement. It can be observed that the beams can resist Brefeldin_A more loadings as the increase in the steel ratio ��wx, and the beam strength will probably increase further when more wall reinforcement is provided. However, it is impractical to further increase the wall reinforcement ratio because of steel congestion. In fact, ��wx = 1.8% is already a rather high steel ratio for the walls.