In large bowl, beat cake mix and water with electric mixer on low speed 30 seconds. Scrape bottom and sides of bowl; beat on medium speed 1 minute. Divide batter evenly between pans; pans will be full.
Bake 20-22 minutes or until toothpick inserted in center comes out clean. Cool cakes in pans 15 minutes. Gently pull cakes out of pans; cool completely on grid.
In large bowl, whisk cream and confectioners' sugar with electric mixer to soft peaks. Add piping gel and vanilla. Continue whisking until stiff peaks form. Divide cream in half. Reserve 1/2 cup strawberries; fold remaining strawberries into half of whipped cream.
To assemble, spread 1/3 of strawberry whipped cream on first cake layer. Repeat with remaining layers. Ice outside of cake with plain whipped cream. Top with reserved 1/2 cup strawberries. Refrigerate until ready to serve.