Op amp has a biased output
I would say the output was offset at 1 volt and this is approximately 100 times higher than the offset on the input waveform. Given your amp is configured to have a gain of about 100, there is no surprise here.

The triangulated output is due to the poor gain-bandwidth-product of the op-amp you chose. You want a gain of 100 and you are feeding it 18kHz and it has a GBWP of 1 million Hz.

If the gain is 100, then the "usable" bandwidth of the circuit is 10 kHz but you are exceeding that with your 18 kHz signal hence the circuit acts like a low pass filter at about 10 kHz.