It is impossible for the city's economy not to collapse. Using averages....
Beginning population: 2.3x106
Week #1: 22.5% of the city destroyed, leaving 77.5% of the city.
Week #2: 22.5% of the remaining city destroyed, leaving 60.06% of the city.
Week #3: 22.5% of the remaining city destroyed, leaving 46.55% of the city.
Week #4: 37.5% of the remaining city destroyed, leaving 29.1% of the city.
It is impossible that no population destruction occured before this moment. At least 50% of the population would be gone by now — and that's assuming everyone was willing to stick it out. However, by your rules, only 22.5% of the population is destroyed, leaving 1,782,500 people. However, AT LEAST 1,000,000 of those people have nowhere to live or work.
Week #5: 22.5% of the remaining city destroyed, leaving 22.5% of the city.
Week #6: 22.5% of the remaining city destroyed, leaving 17.47% of the city.
Week #7: 22.5% of the remaining city destroyed, leaving 13.54% of the city.
Week #8: 37.5% of the remaining city destroyed, leaving 8.46% of the city.
Somehow, only another 22.5% of the population has been destroyed, leaving 1,381,437 people. However, despite the loss of 1,000,000 people, AT LEAST 1,200,000 people still have no where to live or work.
By week #12... only 2.5% of the city remains.
Reality: Your city's economy probably collapsed after the first attack but definitely collapsed after the second. The whole city would be evacuated the day after the second attack by any sensible government. It would be evacuated in a panic the day before the third attack regardless the government. Even the heros are long gone. The only people remaining are looters, and they're gone shortly after the fourth attack. Only the drunk dude sleeping under the yet-to-be-destroyed viaduct remains.
City economies basically depend on (a) stability, (b) food imports, (c) utility infrastructure, and (d) law and order.
(d) was lost during the first attack. You can't lose the better part of 25% of a city and not have panic and looting. The average number of cops to citizens is about one for every 250 people. It doesn't take much panic at all before the police are completely overwhelmed.
(b) and (c) were lost during the second attack when every shipper decided the loss of trucks, trains, planes, and boats weren't worth the risk. People are panicking and 40% of street access is gone, so local distribution from regional or even in-city distribution centers collapses. The do-gooders who came in after the first attack start to leave after the second and are dust in the wind after the third — at best.
Further, most cities have very limited distribution of gasoline, natural gas, and water. Most of your electricity would be gone, too. Most people don't know that there is rarely any redundancy for natural gas and water trunk lines. Once you lose the trunk, the whole city goes without.
(a) is lost the moment somebody realizes the food stopped coming.
What you've asked for is simply impossible.