What is one reason that the constitutional convention decided they needed document to replace the articles of confederation

They decided this because the Articles of Confederation was weak and was not able to control their citizens

The Constitutional Convention (1787) was a convention called to amend the Articles of Confederation, a Constitution whose inefficacy had brought about severe economic troubles in the newly born nation. However, soon the delegates realized that amending it would not be enough and the whole document would have to be replaced, instead. One of the reasons they decided to replace it was to establish a new central and strong government that could levy taxes.

Under the Articles of Confederation, the government could only raise money by borrowing from foreign governments, selling western lands or asking the states for funds, which had the option to reject the request anyway. This made it impossible for the U. S. government to pay the nation expenses and debts from the American Revolution and to secure new funds.