The axial and lateral monotonic and cyclic behavior of helical pile foundations was investigated and new helical screw systems suitable for seismic loadings were developed. More than one hundred full scale field load tests were conducted on instrumented helical screw piles installed in cohesive soil. The piles included: plain helical screw piles (P-HSP); grouted (G-HSPs); fiber reinforced polymer FRP-G-HSPs; and reinforced grouted RG-HSPs. The RG-HSP piles axial capacity was more than twice that for PHSP, with minimal reduction after cyclic loading, and their lateral capacity was more than 3 times the PHSPs capacity. A 3-D finite element model was established