Glass fiber-reinforced polymer (GFRP) ties are used as structurally and thermally efficient shear connectors for precast concrete sandwich panels (PCSPs) to link the two concrete wythes through a layer of insulation. The excellent mechanical properties and high thermal resistance of these ties have resulted in the growing use of PCSPs in building construction. Several experiments were conducted during the last few years to investigate the optimal distribution of GFRP ties, level of composite action achieved, and minimum required embedment depth for ties. An emerging application for PCSPs is the wall panels for tornado-resistant buildings (e.g. tornado shelters). The lightweight, structural efficiency, thermal and sound insulation, and speed of construction are the main advantages of these panels. This paper introduces the use of large diameter GFRP ties (#5) in 14 in. thick (5-4-5) PCSPs to resist the significantly high wind pressure of tornado zones. The main objective of this research is to experimentally investigate the flexural capacity, horizontal shear capacity, and deflection of tornado-resistant PCSPs using large diameter GFRP ties. A 32 ft long, 4 ft wide, and 14 in. thick panel was fabricated by Concrete Industries Inc., Lincoln, NE using 12#5 GFRP ties and tested at the structural laboratory of the University of Nebraska-Lincoln in Omaha. Testing results indicated that the design of the panel is adequate for resisting the tornado wind pressure calculated according to FEMA 361; and the number, size, and distribution of GFRP ties used in the tested panel are adequate for resisting horizontal shear and achieving the flexural capacity of a fully-composite panel. Panel deflection predicted using truss model was found to be very close to actual panel deflection. The failure mode of the tested panel was the pullout of ties rather than the rupture of ties, which indicated that deeper embedment of ties, is needed to fully utilize the GFRP ties used.