evg0101

Thanks! I edited the original post to include the plan from the engineer showing the design of the building. Does this help? all upper level columns have the same amount of rebar, not just exterior walls.. Yes, I know this. Thanks! Thanks. I doubt I will have access to reports of tests for conducting the geotechnical investigation. In addition to vertical loads during normal times, I am also concerned about dynamic lateral loads during seismic activity. Can you take a look at the updated pictures in the original post and see if they can help?

It does "seem" light?! ALL columns on the upper floors are like that, they seem evenly spaced and close enough but all like that. Horizontal bars I think are ok as they are dense. It is vertical bars that seem to be of concern. Pls take a look at the attached pic. The top photo also shows lower level columns that have far more bars. There are indeed other structural elements like elevators shafts and staircases fully enclosed in concrete walls, there are also additional cast concrete walls i.e. diaphragms on each floor... Yet the columns do look like light to me too... You can never know enough, see what has happened to the Millennium Tower...

It was in 2008 but for the reasons outlined above I don't think it is now, but thanks:) Btw, how do you like my suggested construction idea for the Millenium Tower, would it work (corner end bearing piles)?

Even when there is a stock market crash property prices never really plunge unless there was a bubble building, prices just dont grow as fast, the rate of growth slows. When real estate is bought and sold for investment, prices tend to go up faster, the only way for a stock market crash to bring the housing market down is if banks start foreclosing and excess supply develops. This is still a great time to buy using leverage, interest rates are at 50-yr lows after the 2008 bubble there was a correction, 2008 was a horrible time to buy, during 2005-2008 developers were aggressively building, now is not the same. Unemployment and interest rates are irrelevant (e.g. 1980 both in double digits and home prices kept growing) they only matter when it's a buyer's market. I will buy in CA now sell when the price doubles in the early 20th and retire in FL:) Reading on theMillennium Tower, I guess doing bored piles till 200 feet depth would be very costly for 50 or however many columns. But I would at least construct 4 corner piles as end-bearing piles rather than friction piles that way swaying could be prevented.

it appears this building does have friction piles (instead of end-bearing piles) as bedrock is too deep: The foundation of the structure is a concrete slab built on 60–90-foot-deep (18–27 m) concrete friction piles through the fill and Young Bay Mud, and embedded into dense Colma sand. A number of other buildings in this part of San Francisco required use of end-bearing piles, which load directly onto bedrock, rather than friction piles; however, the subsurface conditions in San Francisco vary greatly and there are a number of other buildings supported on a deep foundation system bottomed in dense Colma sand, similar to the Millennium Tower. If end-bearing piles into bedrock were used for the Millennium Tower, they would have needed to be approximately 200 feet (61 m) deep to bear onto bedrock, up to three times longer than the existing friction piling solution used. An examination in 2016 showed the building had sunk 16 inches (41 cm) with a two-inch (5.1 cm) tilt at the base and an approximate six-inch (15 cm) tilt at the top of the tower. The building is leaning toward the northwest.

Thanks for sharing! hehe It appears this building has a raft/mat foundation and settling faster than expected. Its better to have bored piles into bedrock that way uneven settling can be avoided.

Thank you for your quick reply. I've done key due diligence and got all the assurances that the construction is sound. I have no engineering background but I figure its not possible to determine based on the limited information provided. At lower levels, there are massive retaining walls as well, the so-called diaphragms. Understood. Thanks! Correct. Its SF bay area. It's a small apartment 1000 sq.feet though still costs quite a bit. But I expect the price of this purchase to double by 2020. Bank foreclosed property is drying up, there will be a supply crunch and developers have been underbuilding despite growing population and increasing population densities in inner cities. Plus banks are sitting on ungodly piles of hoarded cash, they won't let inflation eat up trillions of dollars, sooner or later they will start lending, the Fed is printing money like crazy. Real estate is a great inflation hedge so I figured it's a good time to buy as an investment while prices are still low, but wanted to make sure its a sound engineering design..

We are planning to buy an apartment in a 25-floor high rise building. The building is said to be in compliance to withstand a magnitude 8 earthquake (on the Richter scale). The building is currently under construction and the picture posted is taken from the 15thfloor. I have some doubts if there is enough rebar material in load bearing columns (rebar size is #8 or #9 imperial, I think reasonably thick). As you see, there are only 10 bars in a column measuring 2 by 3 feet. I have seen other constructions with a lot more bars in a column in a similarly high rise building. Is this sound enough engineering of a column for a high rise in a seismic zone or I am missing something and there are many other factors to consider? The columns at the ground level are much bigger with more bars inside. Thanks! Edit: I got too impatient and obtained a plan from the engineer, which I attach below. I also updated the rebar picture. Can I know with greater certainty if the rebar in the column is adequate now that we can see the overall building design? Many thanks for your views on this again.