Experimental Study on the Damage of Bridge Pier under the Impact of Rockfall

Table 4

Peak values and crack conditions.

Specimen	Falling height (m)	Hitting speed (m/s)	Impact energy (J)	Column top displacement (mm)	Maximum impact force (kN)	Number of concrete spalling grids	Crack conditions
S4.1-1	1	4.43	548.8	4.3	123.96	1	Slight depression at impact, no obvious crack
S4.1-2	2	6.26	1097.6	8.2	175.31	4	A horizontal crack 4 cm long and 0.5 mm wide began to appear near the front of the impact point
S4.1-3	3	7.67	1646.4	17.4	214.71	17	Obvious cracks appeared at the back of the impact point, and small cracks also appeared at the upper and lower 20 cm near the crack
S4.1-4	4	8.85	2195.2	35.3	247.92	44	Cracks appeared at the column bottom, and the small cracks expanded into cracks. The horizontal plane of the impact position formed a penetrating crack, and the large area of concrete spalled at the impact point
S8.3-1	1	4.43	548.8	4.6	82.64	1	The impact point showed sag without obvious crack
S8.3-2	2	6.26	1097.6	8.6	116.87	3	Cracks appeared on the back of the impact site, and the depression at the impact site was intensified with crack propagation
S8.3-3	3	7.67	1646.4	17	143.14	17	Obvious cracks began to appear on the back of the impact point, around which there were small cracks
S8.3-4	4	8.85	2195.2	48.5	165.29	43	There are cracks in many places of the column and some cracks in the bottom
S2.1-1	1	4.43	548.8	6.4	61.98	1	The impact point showed sag without obvious crack
S2.1-2	2	6.26	1097.6	13.6	87.65	4	The horizontal crack appeared near the impact point, the depression was intensified, and there are small cracks on the back
S2.1-3	3	7.67	1646.4	45.1	107.35	21	An obvious crack appeared on the back of the impact point, and there were many small cracks within a range of 20 cm above and below the crack
S2.1-4	4	8.85	2195.2	82.5	123.96	37	A crack appeared at the bottom, and the previous crack expanded into a crack

Note. S4.1-2 means that the pendulum ball hits the height 1/4 of the column with a fall height of 2 m.