Strengthening Pensions through Investment in Infrastructure Act This bill modifies the criteria for private activity bonds to specify that the use of public infrastructure property by a public pension fund is not considered a private business use. (The private business use test is one of the tests used to determine if a bond is a taxable private activity bond rather than a tax-exempt bond.) The bill also specifies that public infrastructure property is not considered investment-type property for the purpose of determining whether a bond is a taxable arbitrage bond. (Taxable arbitrage bonds are used to acquire higher yielding investments, or to replace funds which were used directly or indirectly to acquire higher yielding investments.)