Apple Inc. spent more than $517 million on Silicon Valley real estate this week, expanding its owned office footprint even as many technology peers scale back. The iPhone maker paid about $350 million for a newly built, two-building campus in Sunnyvale that spans roughly 380,000 square feet. Earlier in the week it bought the Tantau Avenue complex near its Cupertino headquarters for about $160 million, lifting the week’s outlay to over half a billion dollars. The investments reflect Apple’s strategy of converting leased properties into owned facilities, giving the company greater control over workspace design and security for future hardware and services projects.